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Análisis de la variabilidad en poblaciones naturales de Solanum, secciones Lycopersicon y BasarthrumZuriaga García, Elena 09 November 2009 (has links)
En el Banco de Germoplasma del Instituto de Conservación y Mejora de la Agrodiversidad Valenciana de la Universidad Politécnica de Valencia (COMAV) se mantienen actualmente más de 7000 entradas de especies hortícolas, incluyendo cultivares locales españoles y especies silvestres. Entre estas entradas se incluyen 3500 de la sección Lycopersicon y 144 de la sección Basarthrum del género Solanum. Para que el empleo de estos recursos fitogenéticos sea eficiente es necesario conocer su estructura genética y su taxonomía. El conocimiento de la distribución de la variabilidad existente permite establecer criterios de conservación más racionales y un uso más eficiente de estos recursos para la mejora de las especies cultivadas.
Los objetivos de la presente tesis doctoral se centran en el estudio de las secciones del género Solanum mencionadas previamente. Ambas secciones incluyen especies cultivadas: tomate y pepino dulce. La clasificación y filogenia de las especies pertenecientes a cada una de estas secciones ha sido objeto de controversia durante mucho tiempo y, a pesar del esfuerzo realizado hasta el momento, todavía no se ha alcanzado un consenso definitivo. Esto puede ser debido a una separación reciente de estas especies, que permanecen estrechamente relacionadas y con capacidad de cruzamiento, o a la falta de trabajos en los que se incluya una representación adecuada de toda la variabilidad presente en estas secciones.
Para analizar la taxonomía de la sección Lycopersicon se ha empleado una amplia representación de materiales de cada una de las especies abarcando todo su rango de distribución. Los análisis realizados identifican 12 especies distintas. Esta clasificación confirma algunas de las nuevas especies propuestas en la sección recientemente, pero no en todos los casos. La nueva especie S. huaylasense aparece claramente separada de S. peruvianum. / Zuriaga García, E. (2009). Análisis de la variabilidad en poblaciones naturales de Solanum, secciones Lycopersicon y Basarthrum [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/6362 / Palancia
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Potential cucurbitacin chemical residues and non-phytotoxic concentration of two phytonematicide formulations in nightshadeMalebe, Agreement Leago January 2019 (has links)
Thesis (M. A. Agriculture (Plant Protection)) -- University of Limpopo, 2019 / The successful cultivation of nightshade (Solanum retroflexum) as a leafy vegetable with
the nutritional potential of contributing to food security in marginalised communities of
Limpopo Province could be limited by high population densities of root-knot (Meloidogyne
species) nematodes. However, the use of Nemarioc-AL/AG and Nemafric-BL/BG
phytonematicides in suppressing nematodes and not being phytotoxic requires the
empirically-developed non-phytotoxic concentration, technically referred to as Mean
Concentration Stimulation Point (MCSP). The MCSP, developed using the Curve-fitting
Allelochemical Response Data (CARD) computer-based model, is crop-specific, hence it
should be developed for every crop. The objective of this study was to investigate the
influence of Nemarioc-AL/AG and Nemafric-BL/BG phytonematicides on growth of
nightshade, accumulation of essential nutrient elements and cucurbitacin residues in
nightshade leaves. Microplots were established by inserting 20-cm-diameter plastic pots
into 10-cm-deep holes at 0.6 m intra-row and 0.6 m inter-row spacing. Each pot was filled
with 10 000 cm3 steam-pasteurised river sand and Hygromix at 3:1. After establishment,
Nemarioc-AL and Nemafric-BL phytonematicides were applied at 7-day interval, whereas,
Nemarioc-AG and Nemafric-BG phytonematicides were only applied at planting. Two
separate experiments for Nemarioc-AL and Nemafric-BL phytonematicides were
conducted in summer (November-January) 2017/2018 under microplot conditions with
each comprising treatments namely; 0, 2, 4, 8, 16, 32 and 64%, similarly, two separate
experiments for the following phytonematicides, Nemarioc-AG and Nemafric-BG
comprised treatments namely; 0, 2, 4, 6, 8, 10 and 12 g arranged in a randomised
complete block design (RCBD), with 12 replications. The nutrient elements in leaf tissues
of nightshade were analysed using the inductively coupled plasma optical emission
spectrometry (ICPE-9000) while, cucurbitacin A and B were
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each quantified using the isocratic elution Shimadzu HPLC Prominence with Shimadzu
CTO-20A diode array detector. Plant growth and nutrient elements variables were
subjected to the CARD computer-based model to generate biological indices to generate
the curves, quadratic equations and the related biological indices (Dm, Rh, k) (Liu et al.,
2003). The MCSP values were calculated using the biological indices of plant or nutrient
element variables which, along with increasing concentration of Nemarioc-AL, Nemafric
BL, Nemarioc-AG and Nemafric-BG phytonematicides, exhibited positive quadratic
relations, with R2 ≥ 25. Using cucurbitacin A and B standards, residues of Nemarioc
AL/AG and Nemafric-BL/BG phytonematicides, were not detected in nightshade leaves,
respectively. Dry root mass and dry shoot mass of nightshade over increasing
concentration of Nemarioc-AL phytonematicide each exhibited a quadratic relationship,
with the models explained by 93 and 61%, respectively. Dry root mass, dry shoot mass,
plant height, chlorophyll content and stem diameter against increasing concentration of
Nemafric-BL phytonematicide each exhibited positive quadratic relationships with the
models explained by 95, 72, 65, 78 and 62%, respectively. Plant height, stem diameter
and dry root mass against increasing concentration of Nemarioc-AG phytonematicide
each exhibited positive quadratic relationships with their models explained by 93, 88 and
91%, respectively. Dry shoot mass and stem diameter against increasing concentration of
Nemafric-BG phytonematicide each exhibited positive quadratic relationships with their
models explained by 94 and 84%, respectively. Na, Fe and K over increasing
concentration of Nemarioc-AL phytonematicide each exhibited positive quadratic
relationships with their associations explained by 96, 91 and 95%, respectively. Zn over
increasing concentration of Nemafric-BL phytonematicide exhibited positive quadratic
relationship with the model explained by 98%. Fe over increasing concentration of
Nemarioc-AG phytonematicide exhibited positive quadratic
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relationship with the association explained by 91%. Fe, Na, K and Zn over increasing
concentration of Nemafric-BG phytonematicide each exhibited positive quadratic
relationships with their associations explained by 81, 90, 80 and 89%, respectively,
whereas, on the contrary, Zn over increasing concentration of Nemarioc-AG
phytonematicide exhibited negative quadratic relationship with the association
explained by 96%. Significant (P ≤ 0.05) plant variables were subjected to CARD, to
generate biological indices which were used to compute the MCSP using the relation:
MCSP = Dm + Rh/2 and the overall sensitivity value (∑k). In Nemarioc-AL
phytonematicide trial, MCSP = 3.02% and ∑k = 1 for plant variables, whereas, MCSP
and ∑k for nutrient elements were 12.09% and 1, respectively. In Nemafric-BL
phytonematicide trial, MCSP = 3.08% and ∑k = 0 for plant variables, while MCSP =
2484.14% and ∑k = 0 for nutrient elements. In Nemarioc-AG phytonematicide trial,
MCSP = 3.47 g and ∑k = 0 for plant variables, whereas, for nutrient elements MCSP =
8.49 g and ∑k = 1. In Nemafric-BG phytonematicide trial, MCSP = 4.70 g and ∑k = 0
for plant variables, whereas, MCSP =723.75 g and ∑k = 1 for nutrient elements. In
conclusion, the application of Nemarioc-AL/AG and Nemafric-BL/BG phytonematicides
had the ability to stimulate the growth of nightshade and enhance the accumulation of
the selected nutrient elements without leaving cucurbitacin chemical residues in leaf
tissues of nightshade. / National Research
Foundation (NRF)
and the Land Bank Chair of Agriculture
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Aprovechamiento de las especies Solanum peruvianum en la mejora del tomateCampos, Gabriela Natalia 23 April 2018 (has links)
La entrada PI 126944 de S. peruvianum ha sido descrita como resistente a distintos estreses bióticos, entre ellos a la enfermedad del rizado amarillo del tomate (Tomato yellow leaf curl disease, TYLCD). En trabajos previos realizados en el Instituto Universitario para la Conservación y Mejora de la Agrodiversidad Valenciana (COMAV) se obtuvieron tres híbridos interespecíficos entre esta entrada y el tomate cultivado, empleando el rescate de semillas inmaduras. En trabajos posteriores se desarrollaron generaciones más avanzadas a partir de estos materiales, incluyendo hasta las generaciones pseudo-F6 y retrocruces hacia la especie cultivada de algunas de las generaciones pseudo-Fn. Con objeto de aprovechar estos materiales en la mejora del tomate cultivado se inició, en trabajos anteriores del grupo, el desarrollo de un conjunto de líneas de introgresión (Introgression lines, ILs) que contengan el genoma de la entrada PI 126944 en el fondo genético de S. lycopersicum. Para tener correctamente representado el genoma de la especie donante en el fondo genético del tomate es necesario obtener un gran número de descendientes, por lo que es necesario optimizar los protocolos.
El primer objetivo de esta tesis fue el estudio de distintos factores implicados en la superación de las barreras de incompatibilidad, con objeto de conseguir un elevado número de descendientes y maximizar la probabilidad de introgresar el genoma de PI 126944 en el conjunto de ILs. Se llevaron a cabo tres ensayos de retrocruce, iniciados con diferentes plantas de las generaciones pseudo-F4, pseudo-F5 y pseudo-F6. El genotipo de los parentales resultó ser un factor determinante en la obtención de descendencia, por lo que se recomienda utilizar el máximo número de genotipos distintos, con objeto de maximizar la probabilidad de obtener progenie. Se llevó a cabo una prueba de medios de cultivo que permitió seleccionar la combinación más adecuada de auxinas y citoquininas para el cultivo de semillas inmaduras y posterior regeneración de plantas. También se estudió el efecto del número de días transcurridos desde la polinización hasta la recolección de los frutos.
Tal y como se ha comentado anteriormente, esta colección del ILs presenta interés por la resistencia del parental donante a TYLCD. Una vez se complete la colección, se evaluará por su resistencia a esta enfermedad. Los estudios previos han mostrado que se trata probablemente de una resistencia poligénica, cuya expresión a menudo es más dependiente de las condiciones ambientales y de otros factores. En estos casos, el empleo de un solo testigo resistente y otro susceptible no es suficiente para determinar con exactitud el nivel de resistencia de los materiales en estudio. La disponibilidad de controles con distintos niveles de resistencia permitiría realizar un fenotipado más preciso. Un grupo de investigadores del "Volcani Center" desarrollaron una escala compuesta por siete líneas con diversos niveles de resistencia a TYLCD, introgresada a partir de distintas especies silvestres. En el marco de esta tesis se evaluó el comportamiento de esta escala en siete ensayos distintos, cuatro de ellos llevados a cabo en el COMAV-UPV y los otros tres en el Instituto Nacional de Ciencias Hortícolas de Cuba. Se compararon dos aislados de TYLCV (Tomato yellow leaf curl virus), una de las especies causantes de TYLCD, diferentes métodos de inoculación, dos estados de desarrollo de la planta y distintas condiciones ambientales. Los síntomas fueron más leves que los obtenidos en las condiciones ensayadas por los autores que desarrollaron la escala, si bien el orden de las líneas en la escala se mantuvo, con pocas excepciones. Sin embargo, en la mayor parte de las condiciones, la respuesta obtenida no correspondió a una escala gradual, ya que se observó una gran diferencia entre los valores de síntomas de las líneas susceptibles y las resistentes, siendo muy pequeñas las difer / Accession S. peruvianum PI 126944 has been reported as resistant to several biotic stresses, among them to Tomato yellow leaf curl disease, (TYLCD). In previous works carried out in the "Instituto Universitario para la Conservación y Mejora de la Agrodiversidad Valenciana" (COMAV) three interspecific hybrids between this accession and cultivated tomato were obtained, using immature seeds rescue. In subsequent works more advances generations from these materials were developed, including until the pseudo-F6 generations and backcrosses to the cultivated species of some of the pseudo-Fn generations. With the aim of taking advantage of these materials in the improvement of cultivated tomato, in previous works of the group, the development of a set of Introgression lines (ILs) that contain the genome of the accession PI 126944 in the genetic background of S. lycopersicum was initiated. The obtaining of a large number of descendants is necessary in order to have correctly represented the genome of the donor species, thus there is the need to optimize the protocols
In this sense, the first aim of this work was the study of several factors involved in the overcoming of the incompatibility barriers, to obtain a high number of descendants and maximize the probability of introgressing the genome of PI 126944 in the set of ILs. Three backcross assays were carried out, initiated with different plants of the generations pseudo-F4, pseudo-F5 and pseudo-F6. The parental genotype resulted a determinant factor in the obtaining of descendants, so the recommendation is the use of the maximum number of different genotypes, in order to maximize the probability of obtaining progeny. A proof of different culture media was carried out, which allowed the selection of the better combination of auxins and cytokinins to grow immature seed and regenerate plants.
The effect of the number of days from pollination to fruit harvest was also studied.
As mentioned before, the collection of ILs results of interest, given the resistance of the donor parental to TYLCD, among others traits. Once the collection is completed, it will be evaluated for its resistance to this disease. The previous studies showed that it is probably a quantitative resistance, whose expression is often more dependent of the environmental conditions and of other factors. In these cases, the use of only one resistant and one susceptible control is not sufficient to determine with accuracy the level of resistance. Availability of controls with different levels of resistance would allow a more precise phenotyping. A group of researchers of the "Volcani Center" developed a scale that consisted of seven lines with different levels of resistance to TYLCD, introgressed from different wild species. In this work, the response of this scale in seven distinct assays was evaluated, four of them carried out in the COMAV-UPV and the others three in the "Instituto Nacional de Ciencias Hortícolas de Cuba". Two isolates of TYLCV (Tomato yellow leaf curl virus), one of the species causing TYLCD, different inoculation method, two development stages of the plant and several environmental conditions were evaluated. In general, the symptoms were more slight that the obtained in the conditions assayed by the authors that developed the scale, although the order of the lines in the scale were maintained, with few exceptions. However, in most of the conditions, the response obtained did not correspond to a graded scale, since there were high differences among the symptom scores of the susceptible and the resistant lines, with very small the differences among the resistant lines. These results suggest the possibility to reduce the number of lines to employ in each concrete condition, selecting the most susceptible, the most resistant and another with intermediate levels of resistance. / L'entrada PI 126944 de S. peruvianum ha sigut descrita com a resistent a diferents estresses biòtics, entre ells a la malaltia de l'arrissat groc de la tomaca (Tomato yellow leaf curl disease, TYLCD). En treballs previs realitzats en el "Instituto Universitario para la Conservación y Mejora de la Agrodiversidad Valenciana" (COMAV) es van obtenir tres híbrids interespecífics entre aquesta entrada i la tomaca cultivada, emprant el rescat de llavors immadures. En treballs posteriors, es van desenvolupar generacions més avançades a partir d'aquests materials, incloent fins a les generacions pseudo-F6 i retrocreuaments cap a l'espècie cultivada d'algunes de les generacions pseudo-Fn. A fi de aprofitar aquests materials en la millora de la tomaca cultivada es va iniciar, en treballs anteriors del grup, el desenvolupament d'un conjunt de línies d'introgressió (Introgression lines, ILs) que continguen el genoma de l'entrada PI 126944 en el fons genètic de S. lycopersicum. Per a tenir correctament representat el genoma de l'espècie donant en el fons genètic de la tomaca és necessari obtenir un gran nombre de descendents, per la qual cosa és necessari optimitzar els protocols.
El primer objectiu d'aquesta tesi va ser l'estudi de diferents factors implicats en la superació de les barreres d'incompatibilitat, a fi d'aconseguir un elevat nombre de descendents i maximitzar la probabilitat d'introgressar el genoma de PI 126944 en el conjunt de ILs. Es van dur a terme tres assajos de retrocreuament, iniciats amb diferents plantes de les generacions pseudo-F4, pseudo-F5 i pseudo-F6. El genotip dels parentals va resultar un factor determinant en l'obtenció de descendència, per la qual cosa es recomana utilitzar el màxim nombre de genotips diferents, a fi de maximitzar la probabilitat d'obtenir descendència. Es va dur a terme una prova de medis de cultiu que va permetre seleccionar la combinació més adequada d'auxines i citoquinines per al cultiu de llavors immadures i posterior regeneració de plantes. Es va estudiar l'efecte del nombre de dies transcorreguts des de la pol·linització fins a la recol·lecció dels fruits, havent-se obtingut resultats diferents.
Tal com s'ha comentat anteriorment, aquesta col·lecció de ILs presenta interès per la resistència del parental donant a TYLCD. Una vegada es complete la col·lecció, s'avaluarà per la seua resistència a aquesta malaltia. Els estudis previs han mostrat que es tracta probablement d'una resistència quantitativa, l'expressió de la qual sovint és més depenent de les condicions ambientals i d'altres factors. En aquests casos, l'utilització d'un sol control resistent i un altre susceptible no és suficient per a determinar amb exactitud el nivell de resistència dels materials en estudi. La disponibilitat de controls amb diferents nivells de resistència permetria realitzar un fenotipat més precís. Un grup d'investigadors del "Volcani Center" van desenvolupar una escala composta per set línies amb diversos nivells de resistència a TYLCD, introgressada a partir de diferents espècies silvestres. En el marc d'aquesta tesi es va avaluar el comportament d'aquesta escala en set assajos diferents, quatre d'ells duts a terme en el COMAV-UPV i els altres tres en el "Instituto Nacional de Ciencias Hortícolas de Cuba". Es van comparar dos aïllats deTYLCV (Tomato yellow leaf curl virus), una de les espècies causants de TYLCD, diferents mètodes d'inoculació, dos estats de desenvolupament de la planta i diferents condicions ambientals. Els símptomes van ser més lleus que els obtinguts en les condicions assajades pels autors que van desenvolupar l'escala, si ben l'ordre de les línies en l'escala es va mantenir, amb poques excepcions. No obstant açò, en la major part de les condicions, la resposta obtinguda no va correspondre a una escala gradual, ja que es va observar una gran diferència entre els valors de símptomes de les línies susceptibles i les resiste / Campos, GN. (2018). Aprovechamiento de las especies Solanum peruvianum en la mejora del tomate [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/100858 / TESIS
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Auxinas dependem de peróxido de hidrogenio nas respostas das raízes de tomateiro á deficiência de nitrogênio /Lúcio, José Clebson Barbosa January 2019 (has links)
Orientador: Rogério Falleiros Carvalho / Resumo: O nitrogênio (N), elemento essencial ao crescimento e desenvolvimento vegetal, é absorvido principalmente como nitrato (NO3-). Esse elemento pode controlar a arquitetura de raízes e dessa forma favorecer a absorção de nutrientes pelas plantas. Para isso, tem sido mostrado que esses eventos estão relacionados ao controle hormonal, especialmente as auxinas, pois esse hormônio controla o crescimento das raízes de modo dependente de NO3-. Entretanto, esses mecanismos são complexos, pois dependem de várias moléculas, especialmente peróxido de hidrogênio (H2O2), o qual parece atuar nas sinalizações das auxinas em situações estressoras nas plantas, a exemplo da deficiência de N. Entretanto, a forma como auxinas e H2O2 interagem nas raízes sob deficiência de N foi pouco explorado. Assim, objetivou-se verificar se as auxinas dependem de H2O2 nas respostas das raízes de tomateiro à deficiência de NO3-. Para isso, plantas de da cultivar Micro-Tom de tomateiro foram cultivadas em hidroponia sob suficiência e deficiência de NO3-, ambas com presença e ou ausência de inibidor de transporte de auxinas, o (ácido 2,3,5-triiodo-benzóico- TIBA) e inibidor do acúmulo de H2O2 (Catalase). O delineamento experimental foi inteiramente casualizado, disposto em fatorial 2x4, com três repetições. Foi analisado comprimento e biomassa seca da parte aérea e biomassa seca, comprimento, área e volume das raízes. Além disso, foi quantificado conteúdo de MDA e H2O2. A deficiência de NO3- diminuiu o crescimento... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Nitrogen (N) is essential for plant growth and development, and is mainly absorbed as nitrate (NO3-). It also controls root architecture, improving plant nutritional status. These characteristics are related to hormonal control, especially by auxins. Auxins control root growth via NO3-dependent cell expansion, but these mechanisms are complex and depend on several molecules. Hydrogen peroxide (H2O2) appears to act on these auxins signalling in plant stress situations. However, how auxins and H2O2 interact in roots under N deficiency has not been well explored. Therefore, this study aimed to verify if auxins depend on H2O2 for responses of tomato roots to N deficiency. Micro-Tom plants were grown in hydroponic systems under sufficiency and deficiency of NO3-, both with and without auxin transport inhibitor, 2,3,5-triiodo-benzoic acid (TIBA), and the inhibitor of H2O2 accumulation (Catalase) in plants. The experiment was carried out in a completely randomized design in a factorial scheme (2x4) with three replications. Shoot length and dry biomass, as well as root dry biomass, length, area and volume were analysed. In addition, MDA and H2O2 content were also quantified. NO3- deficiency reduced shoot growth and, interestingly, promoted higher root growth. Furthermore, TIBA inhibited root growth under both NO3- conditions and the presence of catalase in NO3-deficiency resulted in lower root growth. These results show that auxins depend on H2O2 for tomato root responses to N defici... (Complete abstract click electronic access below) / Mestre
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The interaction between root knot nematodes (Meloidogyne spp.) and soft rot Enterobacteriaceae (Pectobacterium spp.) and their host Solanum tuberosumMongae, Aobakwe Oratile January 2013 (has links)
Meloiodgyne incognita, one of the most aggressive plant parasitic nematodes species on potato in South Africa, belongs to a group of plant parasitic nematodes commonly known as root knot nematodes (RKN). This group of nematodes is widely distributed throughout the world. Meloidogyne spp. cause major economic losses to important crops such as potato and therefore decrease their market value in many countries across the world. The second stage juveniles are the only mobile and infective phase of the root knot nematode. As they infect host roots, they create wounds that can be used by other plant pathogens to penetrate the host in large numbers. The most effective management strategy for root knot nematodes is the use of nematicides such as Temik and Methyl bromide. However, these have been banned due to adverse on the environment. Therefore, Meloidogyne spp. will inevitably become a big problem in the potato industry of many countries due to the lack of effective alternatives to banned chemicals. Pectobacterium carotovorum subsp. brasiliensis (Pcb) is one of the most important soft rot-causing agents in South Africa. This pathogen belongs to a group of pathogens commonly known as soft rot Enterobacteriaceae (SRE). Bacteria belonging to this group of pathogens are known to cause soft rot and blackleg diseases on potato and other crops. Pcb is known as an opportunistic pathogen that can only penetrate host root tissue through natural openings or wounds that result from a variety of agents. Post penetration, the bacteria will increase in number and cause soft rot and blackleg. As rotting plant tissue disintegrates the bacteria escapes into the soil where it serves as inoculum and can infect healthy hosts.
Many interactions have been documented between Meloidogyne spp. and other plant pathogens but to our knowledge there are no interactions that have been reported between Meloidogyne spp. and Pectobacterium spp. Considering the life cycles of RKN and SRE, we hypothesised that there could be an interaction between the two pathogen groups. Since both RKN and SRE are potato pathogens, they share the same space in the rhizosphere. This likely can lead to synergies and complex formation between the two pathogens. Likely, the wounds created by RKN J2s as they penetrate plant tissue can potentially be used by opportunistic Pcb to infect various hosts. It is from these identified overlaps that the first part of this study focused on investigating the potential interaction between M. incognita and Pcb. The first objective was to determine whether Pcb can attach onto M. incognita J2s and, if this was the case, to determine whether the J2s can disseminate the bacteria as they move around in the environment. The second objective was to determine whether there is a synergistic interaction between RKN and SRE and the combined effect of the two pathogens on their host Solanum tuberosum cv Mondial. The results obtained in the first part of the study strongly suggested that Pcb can attach onto M. incognita J2s and can be disseminated as the J2s move around in the environment. Thus, this indicated that there is a synergistic interaction between M. incognita and Pcb as there was increased disease severity and incidence in plants inoculated with both pathogens compared to those inoculated with individual pathogens. Significantly higher Pcb concentrations were found in plants inoculated with both pathogens. There was no breakage of tolerance to Pcb-caused blackleg on an otherwise resistant cultivar, BP1. The second aim of this study was to determine whether the induction of natural resistance using environmentally friendly resistance inducing chemicals can potentially be used as an alternative to chemical control. To this end, the effect of three inducers at different concentrations, amongst DL-β-aminobutyric acid, Acibenzolar-s-methyl and Messenger on potato plants infected with RKN was compared. The most effective resistance inducer amongst the three was 20mM BABA as it was able to reduce the number of J2s that penetrated host tissue, the number of females in the roots and the rate of egg production. Furthermore, the galling index observed in potato roots was significantly lower when plants were treated with 20mM BABA. Additionally, the reduced rate of RKN infection in plants primed with 20mM led to a decrease in the rate of Pcb infection. / Dissertation (MSc)--University of Pretoria, 2013. / gm2013 / Microbiology and Plant Pathology / Unrestricted
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Molecular characterization of root-knot nematodes (Meloidogyne spp.) parasitizing potatoes (Solanum tuberosum) in South AfricaOnkendi, Edward Makori 16 May 2013 (has links)
Potato (Solanum tuberosum) is regarded as one of the single most important vegetable crops in South Africa, with an average annual production of 2 million metric tons. The potato industry contributes to an average of $ 0.37b worth of potatoes annually. Over the years, potato production in South Africa has been affected by, among other factors, diseases and plant parasitic nematodes particularly root-knot nematodes (Meloidogyne spp.). In infected potato fields, root-knot nematodes cause great damage to the crop leading to substantial losses in yield and compromised produce quality. The direct and indirect damage caused by Meloidogyne species results in revenue loss due to a high number of table and processing potatoes rejected in markets both locally and internationally. The presence of resistance breaking Meloidogyne populations, the withdrawal of methyl bromide and lack of commercially grown resistant cultivars suggests that growers are likely to experience more losses in the future. Furthermore, distribution of seed tubers harbouring root-knot nematodes, which may also be asymptomatic, inadvertently facilitates transmission of these parasites to new areas thus perpetuating the problem. Therefore, for the potato industry to adequately address the threat of root-knot nematodes, accurate identification and quantification of root knot nematode levels in the field as well as in seed tubers is of importance. Currently most methods of identifying Meloidogyne species largely rely on the use of morphological traits. However, it can be a challenge to accurately differentiate between closely related species using morphology and other classical methods. To resolve this, recent trends globally have focused on the development of DNA-based diagnostics to rapidly and accurately identify different Meloidogyne species. This study therefore sought to; (a) develop a PCR-based diagnostic tool for accurate detection and identification of various Meloidogyne species parasitizing potatoes in South Africa; (b) use this tool to map their distribution and; (c)develop real-time PCR (qPCR) techniques for accurate quantification and characterization of tropical Meloidogyne species from infected potato tubers. In this study, of the 78 composite potato tuber samples collected from various potato growing regions across seven provinces, 24% were found infected with M. javanica, 23% with M. incognita, 17% with M. arenaria, 14% with M. enterolobii, 3% M. chitwoodi, 1% M. hapla and 1% as M. artiellia. The identity of the remaining 17% could not be established. The three tropical species; M. javanica, M. incognita and M. arenaria were identified as the dominant species, occurring almost in every region sampled. Meloidogyne hapla and M. enterolobii occurred in Mpumalanga and KwaZulu–Natal respectively while M. chitwoodi was isolated from two growers located within the Free State. In the study the use of HRMC and real-time PCR was also developed for identification and quantification of tropical Meloidogyne species infesting potato tubers. Using these two techniques, we were able to show that Meloidogyne arenaria populations produced specific melting peaks (79.3183± 0.0295°C, P < 0.05) thus distinguishing themselves from M. incognita (79.5025± 0.0224°C, P < 0.05) and M. javanica (79.96 ± 0.0459°C, P < 0.05). Real-time PCR was also able to detect 1.53/100th of a nematode using second stage juveniles. / Dissertation (MSc)--University of Pretoria, 2012. / Microbiology and Plant Pathology / unrestricted
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Estrobilurinas e carboxamidas na produção e qualidade de frutos do tomateiro /Weber, Ronald Ernst Heinrich January 2020 (has links)
Orientador: João Domingos Rodrigues / Resumo: Dois experimentos foram conduzidos em 2018 e 2019 para avaliar os efeitos de diferentes fungicidas de dois importantes grupos: estrobilurinas e carboxamidas, sobre a eficácia fotossintética e produtividade de plantas de tomate, inoculadas com Alternaria sp., em ambiente protegido na Fazenda Ituaú, Salto - SP, Brasil. O delineamento experimental aplicado em ambos os experimentos foi de blocos ao acaso, com oito tratamentos e cinco repetições: testemunha inoculada (água + inóculo), testemunha absoluta (água), azoxystrobina (50,0 g ha-1), boscalida (50,0 g ha-1), azoxystrobina (50,0 g ha-1) + boscalida (50,0 g ha-1), mandestrobina (194 g ha-1), impirfluxam (30 g ha-1), mandestrobina (194 g ha-1) + impirfluxam (30 g ha-1), aplicados em intervalos de 15 dias, totalizando 7 a 8 aplicações no ciclo da cultura. O efeito no desenvolvimento das plantas foi medido pela altura das plantas e produção dos cinco primeiros cachos. A eficiência fotossintética foi calculada pela medição das trocas gasosas, fluorescência da clorofila a, teores de pigmentos fotossintéticos, e produtividade. Os fungicidas apresentaram algumas melhorias nos parâmetros analisados, como melhorando os componentes da eficiência fotossintética e da produção de frutos comerciais, porém sem apresentar diferenças significativas em relação às testemunhas. Os resultados demonstram eficácia no controle de Alternaria sp. aplicando os fungicidas em tomateiro, e também apontam para efeitos adicionais em componentes da eficiênci... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Two experiments were carried out in 2018 and 2019 to evaluate the effects of the application of different fungicides from two important groups: strobilurins and carboxamides, on the photosynthetic efficiency and yield of tomato plants, inoculated with Alternaria sp., grown in greenhouse at Fazenda Ituaú, Salto - SP, Brazil. The experimental design applied in both trials was randomized blocks with eight treatments and five replicates: inoculated control (water + inoculum), absolute control (water), azoxystrobin (50,0 g ha-1), boscalid (50,0 g ha-1), azoxystrobin (50,0 g ha-1) + boscalid (50,0 g ha-1), mandestrobin (194 g ha-1), inpyrfluxam (30 g ha-1), mandestrobin (194 g ha-1) + inpyrfluxam (30 g ha-1), applied at intervals of 15 days, totalizing 7 or 8 applications in the crop cycle. The effect on plant development was measured by plant height and the production of the five initial bunches. The photosynthetic efficiency was calculated from measurements of gas exchange, chlorophyll a fluorescence, content of photosynthetic pigments, and tomato productivity were evaluated. All fungicides positively affected some evaluated parameters, improving photosynthetic efficiency components and commercial fruit production, however without significant difference to the controls. The results demonstrate the efficacy of the use of these fungicides in controlling Alternaria sp. in tomato and also appoint to some additional effects on photosynthesis efficiency components and antioxidant enzym... (Complete abstract click electronic access below) / Doutor
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Interferência de beldroega no tomateiro : suas possibilidade de controle e sua relação com nematóide /Alves, Felipe da Cunha. January 2020 (has links)
Orientador: Leonardo Bianco / Resumo: Sendo a beldroega uma planta infestante da cultura do tomate e uma hospedeira natural de nematoides do gênero Meloidogyne, levanta-se a hipótese de que a ocorrência dessa planta daninha em áreas de plantios de tomate possa interferir no crescimento e produtividade do tomateiro, dependendo do período de convivência, e que existe uma relação da sua ocorrência com a infestação de M. incognita no tomateiro, e que é possível controlá-la com seletividade ao tomateiro. Dessa forma, com este estudo, objetivou-se: a) avaliar se há interferência da beldroega no crescimento e produtividade do tomateiro; b) determinar o período de convivência da planta daninha com a cultura que não afete o crescimento e a produtividade do tomateiro; c) avaliar se a beldroega infestando a cultura do tomate atua como hospedeira de Meloidogyne javanica e com isso reduz a sua infestação no tomateiro; d) estudar a seletividade de herbicidas ao tomateiro visando o controle da beldroega em pré e pós-emergência e) verificar se a velocidade de controle do metribuzim elimina de imediato a interferência dessa planta daninha no tomateiro. Para tanto, esse estudo constou de três experimentos. No primeiro, os tratamentos experimentais consistiram de três períodos de convivência do tomateiro „Dylla‟ com a beldroega (14, 21 e 60 dias após o transplantio), com um tratamento para tomate sem convivência com a planta daninha e outro tratamento para a beldroega sem convivência com a cultura, todos com ou sem a inoculação de ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Purslane is an infesting plant in tomato culture and a natural host of nematodes of the genus Meloidogyne, the hypothesis arises that the occurrence of this weed in tomato plantation areas may interfere in tomato growth and productivity depending on the period coexistence between them. Also that is a relationship between it ́s occurrence and the infestation of M . incognita in tomato and that it is possible to control it with tomato selective products. This study aimed to: a) assess whether purslane interferes with tomato growth and productivity; b) determine the period of coexistence of the weed with the crop that does not affect the growth and productivity of the tomato; c) to evaluate whether purslane infesting the tomato crop acts as host of Meloidogyne javanica and thereby reduces its infestation in tomato; d) to study the selectivity of herbicides for tomato aiming at the control of purslane in pre and postemergence e) to verify if the speed of control of the metribuzim immediately eliminates the interference of this weed in the tomato. This study consisted of three experiments. In the first, the experimental treatments consisted in three coexistence periods of tomato 'Dylla' with purslane (14, 21 and 60 days after transplanting), with a treatment for tomatoes without living with weeds and another treatment for purslane without coexistence with culture, all with or without Meloidogyne javanica inoculation. The treatments were arranged in a randomized block design, in 6 ... (Complete abstract click electronic access below) / Mestre
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Proyecto de inversión para la instalación de una planta productora de alcohol de papa en la provincia de ChotaCruz Pupuche, Linda Marita, Millones Vigil, José Miguel January 2014 (has links)
La producción de alcohol se encuentra relacionada directamente con la producción de Biocombustibles, debido al desplazamiento de importantes volúmenes de alcohol para su conversión en etanol o alcohol anhídrido; usado como complemento o sustituto de la gasolina. Esta situación ha generado que la caña de azúcar, principal materia prima para la elaboración de alcohol se convierta en un “bien escaso” y sea necesario buscar otras potenciales fuentes para su producción. En el Perú, existe también el potencial para producir el mencionado producto, usando los tubérculos como base, especialmente la papa; a través de la conversión de almidones en azúcares y su posterior fermentación y destilación en alcohol etílico. La presente investigación tiene por finalidad demostrar la viabilidad de la instalación de una planta de producción de alcohol de papa en la provincia de Chota, departamento de Cajamarca, con la intención de atender al mercado interno, con un producto de alta calidad, orientado al uso industrial, farmacéutico y cosmético. La metodología desarrollada comprende la determinación de viabilidad de Mercado, Organizacional, Técnico Operativa, Económica financiera y ambiental. Finalmente se concluye que es viable la instalación de una planta de producción de alcohol en la provincia de Chota.
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Mejora genética para la resistencia a los geminivirus tomato yellow leaf curl virus (TYLCV) y tomato yellow leaf curl sardinia virus (TYLCSV) en tomatePérez de Castro, Ana María 16 January 2020 (has links)
[EN] Tomato yellow leaf curl disease (TYLCD) causes great damage in tomato (Solanum
lycopersicum L.) crops in south-eastern Spain and in many tropical and subtropical areas in
the world. The disease is caused by a complex of viruses, all belonging to the genus
Begomovirus, family Geminiviridae. Nine species have been reported causing TYLCD and
six more have been proposed as tentative species. Four viral species associated with
TYLCD are present in Spain. Preventive measures to fight the disease, as well as measures
based on controlling the insect vector (Bemisia tabaci Gen.) are not effective, so the
development of resistant varieties seems the best long term strategy. Given that resistance
has not been reported in the cultivated species, screening for resistance has been focused
on wild tomato relatives. Resistance has been found in different wild species and some
resistant breeding lines and commercial varieties have been developed. Ty-1, derived from
S. chilense LA1969, is the most frequently used gene. Advances in genetic engineering
techniques have also been exploited in developing plant material with pathogen derived
resistance.
However, resistant varieties currently available are not a solution, as with high
inoculum pressure conditions and early infections, plants still develop symptoms and yield
losses are caused. For that reason, many research groups continue working worldwide to
obtain plants with high levels of resistance to TYLCD. Current breeding objectives are the
development of broad spectrum resistance to several begomovirus, the accumulation of
resistance genes from different sources to increase the levels of resistance and the
identification of molecular markers tightly linked to resistance genes, which allows
shortening breeding programmes and accumulating different resistance genes in the same
plant material.
This work has been developed in the research group ‘Breeding for resistance to
Tomato yellow leaf curl disease’ of the Institute for Conservation and Improvement of
Agrodiversity (COMAV). When this project was initiated, several resistant plant materials
had been developed from previous works of the group.
Twelve breeding lines derived from S. chilense LA1932 and LA1938 were
available. These lines were resistant to Tomato yellow leaf curl Sardinia virus (TYLCSV),
the first viral species described in Spain causing TYLCD. It was of interest the evaluation
of resistance in these lines to Tomato yellow leaf curl virus (TYLCV), introduced later in
Spain and spread worldwide. Six breeding lines showed high levels of partial resistance to
TYLCSV and TYLCV. The resistance consisted on attenuation and delay in symptom
development, as well as reduction in viral accumulation. Significant yield losses due to
viral infection were not observed in these lines. These lines also show good horticultural
traits which make them appropriate to be base material for developing commercial hybrids
resistant to both, TYLCSV and TYLCV.
High levels of resistance have also been identified in S. pimpinellifolium
UPV16991. The resistance has already been fixed in the genetic background of S.
lycopersicum. It was convenient to determine the genetic control of the resistance and the
expression in tomato background, before using it in breeding programmes. For these
purposes L102 was selected. L102 belongs to the F6 generation, after the initial cross S.
lycopersicum NE-1 x S. pimpinellifolium UPV16991. Resistance to TYLCV in L102 is
controlled by one gene, with partial recessiveness and incomplete penetrance. Moreover,
the expression of resistance strongly depends on S. lycopersicum background in which it is
introgressed. The highest levels of resistance are obtained when crossing L102 with
vigorous lines. So, we recommend to use UPV16991-derived resistance in the
development of vigorous hybrids in homozygosis or combined with resistance from other
sources.
To exploit resistance derived from UPV16991, L102 and some other lines with the
same origin were crossed with a breeding line homozygous for Ty-1. Resistance was then
evaluated in several plant material heterozygous for both, Ty-1 and the resistance gene
from UPV16991. These plant materials showed higher levels of resistance than
heterozygotes for each of the genes. Resistance in one of the hybrids was even higher than
in homozygotes for each of the genes. These results show that combining resistance from
UPV16991 with Ty-1 is the most practical approach to exploiting this resistance, since it
allows the development of hybrids without the need of fixing the resistance gene in both
parents.
Finally, availability of molecular markers tightly linked to the resistance genes is
essential to accumulate resistance from different sources. Some molecular markers tightly
linked to Ty-1 have been reported. However, in all cases, S. peruvianum-derived Mi gene
interferes with these markers, causing false positive results. In this work, a molecular
marker, JB-1, tightly linked to Ty-1 has been identified. This is a CAPS (Cleaved
Amplified Polymorphic DNA) marker. The presence of Mi, as well as introgressions from
other wild tomato relatives such as S. lycopersicum (formerly Lycopersicon esculentum
var. cerasiforme), S. habrochaites and S. pimpinellifolium do not interfere with the results
for this marker. In addition, the analysis of several plant material with introgressions from
different wild tomato relatives has allowed the location of CT21, the RFLP (Restriction
Fragment Length Polymorphism) marker from which JB-1 was designed. / [ES] La enfermedad del rizado amarillo del tomate (Tomato yellow leaf curl disease,
TYLCD) causa graves daños en los cultivos de tomate (Solanum lycopersicum L.) del
sudeste español y de la mayor parte de las zonas tropicales y subtropicales de todo el
mundo. La enfermedad está causada por un complejo de virus pertenecientes al género
Begomovirus, familia Geminiviridae. Se han descrito nueve especies causantes de TYLCD
y otras seis han sido propuestas. En España están presentes cuatro de las especies virales
asociadas a TYLCD. Las medidas preventivas de lucha contra la enfermedad, así como las
basadas en el control del insecto vector transmisor (Bemisia tabaci Gen.) no resultan
efectivas por si mismas, de forma que el desarrollo de materiales resistentes supone la
mejor estrategia de lucha a largo plazo. Dado que en la especie cultivada no se han descrito
entradas resistentes, la búsqueda de fuentes de resistencia se ha centrado en las especies
silvestres del género relacionadas con el tomate. Se ha encontrado resistencia en distintas
entradas de algunas de estas especies y se han desarrollado líneas de mejora y materiales
comerciales con resistencia procedente de algunas de ellas. El gen Ty-1, derivado de la
entrada LA1969 de S. chilense, ha sido el más empleado para la obtención de líneas e
híbridos comerciales resistentes. Por otra parte, haciendo uso de los avances en las técnicas
de ingeniería genética, también se han desarrollado materiales con resistencia derivada del
patógeno.
Sin embargo, los materiales resistentes disponibles hasta el momento no suponen
una solución definitiva al problema, ya que, con presiones fuertes de inóculo o infecciones
tempranas, las plantas desarrollan síntomas de la enfermedad, produciéndose pérdidas de
producción. Por este motivo, numerosos grupos de investigación continúan trabajando a
nivel mundial con la finalidad de obtener materiales con niveles elevados de resistencia a
TYLCD. Entre los objetivos actuales de mejora se incluyen el desarrollo de resistencia de
amplio espectro a varios begomovirus, la combinación de genes de distinta procedencia
para conseguir mayores niveles de resistencia y la identificación de marcadores
moleculares ligados a los genes de resistencia que permitan acortar los programas de
mejora y acumular en un mismo material genes de resistencia de distintas fuentes.
El grupo de “Mejora para la resistencia a la enfermedad del rizado amarillo del
tomate”, del Instituto de Conservación y Mejora de la Agrodiversidad Valenciana
(COMAV), en el que se ha realizado la presente tesis doctoral, disponía al inicio de la
misma de distintos materiales con resistencia a TYLCD, desarrollados en trabajos previos.
Entre estos materiales se encontraban 12 líneas de mejora derivadas de la entradas
LA1932 y LA1938 de S. chilense, seleccionadas por su resistencia a la especie Tomato
yellow leaf curl Sardinia virus (TYLCSV), la primera especie viral causante de TYLCD
detectada en España. Resultaba de interés evaluar la respuesta de estos materiales a la
especie Tomato yellow leaf curl virus (TYLCV), introducida posteriormente en España y
más extendida a nivel mundial. Seis de las líneas evaluadas han mostrado niveles elevados
de resistencia parcial a TYLCSV y TYLCV, consistente en la atenuación en la
manifestación de síntomas y retraso en el momento de aparición de los mismos, además de
en la reducción de la acumulación viral. Además, no se han observado en estas líneas
pérdidas significativas en el rendimiento como consecuencia de la infección por TYLCV.
Las características agronómicas las hacen apropiadas como parentales para el desarrollo de
híbridos con elevada resistencia a TYLCSV y TYLCV.
Por otra parte, se habían identificado niveles elevados de resistencia en la entrada
UPV16991 de S. pimpinellifolium. Una vez fijada la resistencia en el fondo genético de S.
lycopersicum, y como paso previo al empleo en programas de mejora, era conveniente
determinar el control genético de la misma, así como conocer su expresión en el fondo
genético de la especie cultivada. Para ello se ha empleado la línea L102, que corresponde a
la quinta generación de autofecundación a partir del cruce inicial S. lycopersicum NE-1 x
S. pimpinellifolium UPV16991. Se ha comprobado que la resistencia parcial a TYLCV de
la línea L102 está controlada por un gen con recesividad parcial y penetración incompleta.
Además, la expresión de la misma depende considerablemente del fondo genético de S.
lycopersicum en el que se introgresa, obteniéndose los mayores niveles de resistencia en
cruces con líneas vigorosas. Por todo esto, se recomienda el uso de esta resistencia bien en
homocigosis en el desarrollo de híbridos vigorosos, bien en combinación con resistencia
procedente de otras fuentes.
En este sentido, se decidió evaluar la resistencia en materiales que combinaban el
gen Ty-1 y el gen derivado de UPV16991, ambos en heterocigosis. El nivel de resistencia
en estos materiales ha sido superior al mostrado por los heterocigotos para cada uno de los
genes, e incluso en algún caso se ha superado la resistencia de los homocigotos para cada
uno de los genes. Esto indica que la combinación de la resistencia derivada de UPV16991
con el gen Ty-1 es la aproximación más práctica para la utilización de esta resistencia, ya
que evita la necesidad de fijar el gen de resistencia en ambos parentales.
Por último, para la acumulación de resistencia de distinta procedencia en un mismo
material, resulta imprescindible disponer de marcadores moleculares ligados a los genes de
resistencia. Se han descrito algunos marcadores ligados al gen Ty-1, sin embargo, la
presencia del gen Mi, derivado de S. peruvianum, interfiere con los resultados para estos
marcadores, obteniéndose falsos positivos. En este trabajo se ha identificado un marcador
molecular, JB-1, tipo CAPS (Cleaved Amplified Polymorphic DNA) ligado al gen de
resistencia Ty-1. La presencia del gen Mi, así como introgresiones de otras especies como
S. lycopersicum (antes Lycopersicon esculentum var. cerasiforme), S. habrochaites y S.
pimpinellifolium, no interfieren con los resultados para este marcador. Además, el análisis
de materiales con introgresiones de distintas especies silvestres relacionadas con el tomate
para varios marcadores de la región del Ty-1 ha permitido localizar el marcador CT21, el
RFLP (Restriction Fragment Length Polymorphism) a partir del cual se desarrolló JB-1. / [CA] La malaltia de l’arrissat groc de la tomaca (Tomato yellow leaf curl disease,
TYLCD) causa greus danys als cultius de tomaca (Solanum lycopersicum L.) del sud-est
espanyol i de la major part de les zones tropicals i subtropicals de tot el món. La malaltia
està causada per un complex de virus pertanyents al gènere Begomovirus, família
Geminiviridae. S’han descrit nou espècies causants de TYLCD i altres sis han sigut
proposades. A Espanya estan presents quatre de les espècies virals associades a TYLCD.
Les mesures preventives de lluita contra la malaltia, així com les basades en el control de
l’insecte vector transmissor (Bemisia tabaci Gen.) no resulten efectives per si mateixes, de
manera que el desenvolupament de materials resistents suposa la millor estratègia de lluita
a llarg termini. Atés que en l’espècie cultivada no s’han descrit entrades resistents, la
recerca de fonts de resistència s’ha centrat en les espècies silvestres del gènere
relacionades amb la tomaca. S’ha trobat resistència en distintes entrades d’algunes d’estes
espècies i s’han desenvolupat línies de millora i materials comercials amb resistència
procedent d’algunes d’elles. El gen Ty-1, derivat de l’entrada LA1969 de S. chilense, ha
sigut el més utilitzat per a l’obtenció de línies i híbrids comercials resistents. D’altra banda,
fent ús dels avanços en les tècniques d’enginyeria genètica, també s’han desenvolupat
materials amb resistència derivada del patogen.
No obstant, els materials resistents disponibles fins al moment no suposen una
solució definitiva al problema, ja que, amb pressions fortes d’inòcul o infeccions
primerenques, les plantes desenvolupen símptomes de la malaltia, produint-se pèrdues de
producció. Per este motiu, nombrosos grups d’investigació continuen treballant a nivell
mundial amb la finalitat d’obtindre materials amb nivells elevats de resistència a TYLCD.
Entre els objectius actuals de millora s’inclouen el desenvolupament de resistència d’ampli
espectre a diversos begomovirus, la combinació de gens de distinta procedència per a
aconseguir majors nivells de resistència i la identificació de marcadors moleculars lligats
als gens de resistència que permeten acurtar els programes de millora i acumular en un
mateix material gens de resistència de distintes fonts.
El grup de “Millora per a la resistència a la malaltia de l’arrissat groc de la tomaca”,
de l’Institut de Conservació i Millora de l’Agrodiversitat Valenciana (COMAV), en el que
s’ha realitzat la present tesi doctoral, disposava a l’inici de la mateixa, de distints materials
amb resistència a TYLCD, desenvolupats en treballs previs.
Entre estos materials es trobaven 12 línies de millora derivades de l’entrades
LA1932 i LA1938 de S. chilense, seleccionades per la seua resistència a l’espècie Tomato
yellow leaf curl Sardinia virus (TYLCSV), la primera espècie viral causant de TYLCD
detectada a Espanya. Resultava d’interés avaluar la resposta d’estos materials a l’espècie
Tomato yellow leaf curl virus (TYLCV), introduïda posteriorment a Espanya i més estesa a
nivell mundial. Sis de les línies avaluades han mostrat nivells elevats de resistència parcial
a TYLCSV i TYLCV, consistent en l’atenuació en la manifestació de símptomes, retard en
el moment d’aparició dels mateixos i reducció de l’acumulació viral. A més, no s’han
observat en estes línies pèrdues significatives en el rendiment com a conseqüència de la
infecció per TYLCV. Les característiques agronòmiques les fan apropiades com a
parentals pel desenvolupament d’híbrids amb elevada resistència a TYLCSV i TYLCV.
D’altra banda, s’havien identificat nivells elevats de resistència en l’entrada
UPV16991 de S. pimpinellifolium. Una vegada fixada la resistència en el fons genètic de S.
lycopersicum, i com a pas previ a l’ús en programes de millora, era convenient determinar
el control genètic de la mateixa, així com conéixer la seua expressió en el fons genètic de
l’espècie cultivada. Per a això s’ha emprat la línia L102, que correspon a la quinta
generació d’autofecundació a partir del creuament inicial S. lycopersicum NE-1 x S.
pimpinellifolium UPV16991. S’ha comprovat que la resistència parcial a TYLCV de la
línia L102 està controlada per un gen amb recessivitat parcial i penetració incompleta. A
més, l’expressió de la mateixa depén considerablement del fons genètic de S. lycopersicum
en el que s’introgresa, obtenint-se els majors nivells de resistència en creuaments amb
línies vigoroses. Per tot açò, es recomana l’ús d’esta resistència bé en homozigosis en el
desenvolupament d’híbrids vigorosos, bé en combinació amb resistència procedent d’altres
fonts.
En este sentit, es va decidir avaluar la resistència en materials que combinaven el
gen Ty-1 i el gen derivat d’UPV16991, ambdós en heterozigosis. El nivell de resistència en
estos materials ha sigut superior al mostrat pels heterozigots per a cada un dels gens, i fins i
tot en algun cas s’ha superat la resistència dels homozigots per a cada un dels gens. Açò
indica que la combinació de la resistència derivada d’UPV16991 amb el gen Ty-1 és
l’aproximació més pràctica per a la utilització d’esta resistència, ja que evita la necessitat
de fixar el gen de resistència en ambdós parentals.
Finalment, per a l’acumulació de resistència de distinta procedència en un mateix
material, resulta imprescindible disposar de marcadors moleculars lligats als gens de
resistència. S’han descrit alguns marcadors lligats al gen Ty-1, no obstant, la presència del
gen Mi, derivat de S. peruvianum, interferix amb els resultats per a estos marcadors,
obtenint-se falsos positius. En este treball s’ha identificat un marcador molecular, JB-1,
tipus CAPS (Cleaved Amplified Polymorphic DNA) lligat al gen de resistència Ty-1. La
presència del gen Mi, així com introgresions d’altres espècies com S. lycopersicum (abans
Lycopersicon esculentum var. cerasiforme), S. habrochaites i S. pimpinellifolium, no
interferixen amb els resultats per a este marcador. A més, l’anàlisi de materials amb
introgresions de distintes espècies silvestres relacionades amb la tomaca per a diversos
marcadors de la regió del Ty-1 ha permés localitzar el marcador CT21, el RFLP
(Restriction Fragment Length Polymorphism) a partir del qual es va desenvolupar JB-1. / This research was supported by the “Ministerio de Ciencia y Educación”, project number AGL2001-1857-C04-03. / Pérez De Castro, AM. (2007). Mejora genética para la resistencia a los geminivirus tomato yellow leaf curl virus (TYLCV) y tomato yellow leaf curl sardinia virus (TYLCSV) en tomate [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/135825 / TESIS
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