Submitted by JULIO GARCIA NETO (tec.juliogarcia@ifma.edu.br) on 2018-05-03T00:36:56Z No. of bitstreams: 1 Dissertacao_Julio_Garcia_Neto_2018.pdf: 913083 bytes, checksum: 5a833ab7fa1d0e34d10d5321c04c4640 (MD5) / Approved for entry into archive by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br) on 2018-05-04T17:23:54Z (GMT) No. of bitstreams: 1 garcianeto_j_me_jabo.pdf: 913083 bytes, checksum: 5a833ab7fa1d0e34d10d5321c04c4640 (MD5) / Made available in DSpace on 2018-05-04T17:23:54Z (GMT). No. of bitstreams: 1 garcianeto_j_me_jabo.pdf: 913083 bytes, checksum: 5a833ab7fa1d0e34d10d5321c04c4640 (MD5) Previous issue date: 2018-03-16 / A pulverização foliar de silício (Si) pode beneficiar a produção e a qualidade das hortaliças folhosas, sendo desconhecidos esses efeitos no agrião-da-terra (Barbarea verna) e no almeirão (Cichorium intybus cv. Spadona). Objetivou-se verificar o efeito da pulverização foliar de silício em diferentes fontes e concentrações no teor foliar de Si, nas variáveis de crescimento, no teor foliar de ascorbato e na perda de água durante o armazenamento das hortaliças agrião e almeirão. Foram realizados dois experimentos, com as duas hortaliças cultivadas em vasos (4 dm3) preenchidos com areia, recebendo solução nutritiva. Durante o cultivo, a média da temperatura máxima atingiu 43,1 °C ± 10,6 °C. Utilizou-se delineamento inteiramente casualizado, em esquema fatorial 2 x 4, sendo duas fontes de silício: silicato de potássio e silicato de sódio e potássio estabilizado, e quatro concentrações de Si foliar: 0 (controle); 0,84; 1,68; 2,52 g L-1 de Si, com quatro repetições. As mudas foram transplantadas após 10 dias da emergência para vasos. Foram realizadas três aplicações foliares de Si, a cada dez dias, sendo a primeira realizada aos 28 dias após o transplantio (DAT). A pulverização foliar de silício é viável, para incrementar o acúmulo deste elemento na planta, o crescimento e a biofortificação, e diminui a perda de água da folha pós-colheita do agrião da terra e do almeirão, destacando-se a concentração de 2,52 g L-1 de Si na forma de silicato de potássio. / Silicon (Si) leaf spraying can benefit the production and quality of leafy vegetables. Such knowing is unclear to land cress (Barbarea verna) and root chicory (Cichorium intybus cv. Spadona). This study aimed was verify the effect of silicon leaf spraying under different sources and concentrations in Si leaf content, on growth variables, ascorbate leaf content, and water loss during storage of land cress and root chicory. We carried out two experiments with two vegetables grown in (4 dm3) pots filled with sand, receiving nutrient solution. During growing, the maximum temperature average was 43.1 °C ± 10.6 ºC. A completely randomized design was used in a 2 x 4 factorial scheme, with two sources of silicon: potassium silicate and stabilized sodium and potassium silicate, and four concentrations of leaf spraying Si: 0 (control), 0.84, 1.68, and 2.52 g L-1 of Si, with four replications. The seedlings were transplanted after 10 days of vessel emergence. Three Si leaf sprayings were done every ten days where the first spraying was at 28 days after transplanting (DAT). Silicon leaf spraying is feasible to increase the Si accumulation, plant growth and biofortification and decrease the post-harvest water loss of land cress and root chicory leaves. The Si concentration of 2.52 g L-1 as potassium silicate was highlighted.

A contaminação do ambiente é crescente no mundo, com grandes extensões de áreas afetadas por metais pesados em concentrações que podem representar perigo ambiental. Em face ao aumento da atividade industrial e à agricultura altamente tecnificada, é fundamental o monitoramento dos níveis de metais pesados nos solos, já que as plantas se comportam como mecanismo de transferência de contaminantes do solo para níveis mais altos da cadeia trófica. A ingestão de vegetais contendo elevadas concentrações de metais pesados é uma das principais vias de acesso desses elementos ao corpo humano. No corpo humano, os metais pesados depositam-se no tecido ósseo e gorduroso, ocupando o lugar de minerais nobres. Lentamente liberados no organismo, podem provocar uma série de doenças. O projeto foi dividido em três etapas, cada qual com um objetivo específico: 1º) determinar as concentrações de cádmio, níquel, chumbo, cobalto e cromo em vegetais frequentemente consumidos no Estado de São Paulo, e compará-las com os limites estabelecidos na legislação brasileira; calcular a ingestão diária de metais pesados para estimar o risco à saúde humana; identificar as culturas que apresentam maior potencial de translocação de cádmio para a cadeia alimentar 2º) avaliar os teores de cádmio em hortaliças e nos solos dos campos de produção 3º) avaliar a disponibilidade de cádmio do solo para as plantas com maior potencial de acúmulo do mesmo, com auxilio de extratores químicos e pela técnica de traçador radioativo (109Cd). As amostras vegetais foram coletadas na Companhia de Entrepostos e Armazéns Gerais de São Paulo e a concentração de metais pesados foi determinada por espectrometria de absorção atômica. Todos os vegetais analisados apresentaram concentrações de Cd e Ni abaixo do limite tolerável estabelecido pela legislação brasileira. No entanto, para Pb e Cr, 44% das amostras excederam o limite permitido. Não há nenhuma recomendação estabelecida de limite máximo de tolerância para Co no Brasil. Quanto ao hábito de consumo da população do Estado de São Paulo, a ingestão diária de metais pesados está abaixo da máxima permitida, consequentemente o consumo desses alimentos pode ser considerado seguro e sem riscos à saúde humana. As hortaliças folhosas foram as que mais acumularam Cd. Algumas regiões do Estado de São Paulo apresentaram teores totais de Cd no solo acima do valor de intervenção estabelecido pela CETESB. Entretanto, os vegetais cultivados nesses locais apresentaram teores de Cd inferiores ao limite máximo de tolerância, estabelecido pela ANVISA. É importante, ao estudar a contaminação de áreas agrícolas por metais pesados, observar, além do teor total, outros parâmetros, como a sua disponibilidade para plantas. No experimento em casa de vegetação, as correlações entre o Cd disponível do solo e o Cd acumulado pelas plantas foram significativas somente para a rúcula. O extrator mais eficiente em determinar a fitodisponibilidade de Cd, analisado por meio do Valor L e Razão L, foi o extrator Ácidos Orgânicos / The environmental contamination is increasing worldwide, with large areas affected by heavy metals at concentrations which may pose environmental hazard. Due to industrial activity and highly technical agriculture, it is important to monitor heavy metals levels in soils, since vegetables behave as transfer mechanism of contaminants from soils to higher levels of the food chain. Ingestion of vegetables containing high concentrations of heavy metals is one of the main ways in which these elements enter the human body. Once in human body, heavy metals are deposited in the bone and fat tissues, overlapping noble minerals. Slowly released into the body, heavy metals may cause an array of diseases. The project was divided into three stages, each one with a specific objective: 1st) to determine the concentrations of cadmium, nickel, lead, cobalt and chromium in the most frequently consumed foodstuff in the São Paulo State, Brazil and to compare the heavy metal contents with the permissible limits established by the Brazilian legislation; to calculate intake of heavy metals in human diets for estimating the risk to human health; and to identify crops with the greatest potential for translocation of cadmium into food chain 2nd) to evaluate the cadmium content in leafy vegetables and soils at crop fields 3th) evaluate the phytoavailability of cadmium for leafy vegetables with aid of chemical extractants and radioactive tracer technique (109Cd). The vegetable samples were collected at São Paulo General Warehousing and Centers Company, and heavy metal content was determined by atomic absorption spectrophotometry. All vegetables sampled presented average concentrations of Cd and Ni lower than the permissible limits established by the Brazilian legislation. Exception for Pb and Cr in that 44% of the samples exceeded the maximum permitted limits. The Brazilian legislation has not established a permissible limit for Co contents. Regarding the consumption habit of the population in the São Paulo State, the daily ingestion of heavy metals is below the oral dose of reference, therefore, the consumption of these vegetables can be considered safe and without risk to human health. Leafy vegetables were those most accumulated Cd. Some regions of São Paulo State showed total contents of Cd in soil higher than intervention value established by CETESB. However, the vegetables grown in these areas showed Cd concentrations lower than Brazilian limit established by ANVISA. It is important, when studying environmental contamination by heavy metals, to observe, beside their total content, other parameters, like soil availability. In the greenhouse experiment, the correlation between soil available Cd and plants accumulated Cd were significant only for rocket. The most efficient chemical extractant in determining Cd phytoavailability, analyzed by L Value and L Ratio, were Organic Acids

L'identification et l'amélioration du potentiel pro-vitaminique A des sauces accompagnant les aliments de base pourraient constituer une voie alimentaire de lutte contre la carence en vitamine A (CVA) chez les jeunes enfants au Bénin. La qualité nutritionnelle et la rétention en provitamines A des sauces lors des procédés traditionnels de préparation ont été évaluées au moyen d'une démarche itérative terrain et laboratoire. Une enquête de consommation alimentaire par pesées et mesures anthropométriques auprès de 420 enfants a permis d'évaluer l'état nutritionnel des sujets et l'adéquation des apports en fer, zinc et vitamine A (VA) et d'identifier les principales sources de VA dans l'alimentation. La mangue, les œufs, l'huile de palme rouge (HPR) ou diverses sauces légumes-feuilles (LF) constituent les principaux aliments locaux riches en VA consommés (34,2% des enfants enquêtés). Lorsqu'elles sont consommées, les sauces participent à la couverture de 71 à 129% des apports journaliers recommandés en VA des jeunes enfants. Le suivi au niveau ménage des procédés traditionnels de préparation des sauces les plus prometteuses notamment les sauces LF-amarante à base d'HPR ou de jus de noix de palme (NP), a permis d'identifier les traitements thermiques appliqués aux LF, aux NP ou à l'HPR comme des étapes critiques. Le chauffage de l'HPR à 180-200°C apparaît comme l'étape la plus préjudiciable à la VA. Elle réduit de plus de 70%, et en moins de 3 min, les teneurs en α-carotène, en β-carotène et en activité équivalent rétinol (AER). La violaxanthine, caroténoïde non pro-VA est le seul composé significativement affecté lors du blanchiment des feuilles d'amarante (100°C) mais l'AER reste élevée avec ou sans ajout de potasse traditionnelle. Les sauces formulées à base des ingrédients LF-amarante, NP ou HPR présentent une bonne acceptabilité, une AER élevée et leur consommation pourrait être promue avantageusement dans le cadre d'approches alimentaires de lutte contre la CVA. / The identification and the improvement of the potential in pro-vitamins A of sauces accompanying staple foods could constitute a food-based approach for combating vitamin A deficiency (VAD) among young children in Benin. The nutritional quality and the retention of pro-vitamins A in sauces during traditional home processing has been assessed by using a field-laboratory iterative approach. Anthropometric measurements were used to appreciate subjects' nutritional status. A food consumption survey of 420 young children was conducted to assess the adequacy of iron, zinc and vitamin A (VA) intakes, and to identify the main VA-rich foods eaten by children using the weighed food record method. Mangoes, eggs, red palm oil (RPO), various leafy vegetables (LV) and palm nut juice sauces appeared to be the main VA-rich foods consumed by 34.2% investigated children. When consumed, these LV sauces containing RPO or palm nut juice (PNJ) contributed to the meeting of 71-129% of the recommended VA intake of young children. The traditional processing method of the most promising sauces such as amaranth leaf sauces based on RPO or PNJ was monitored step by step during home visits and allowed identifying the thermal treatments applied to LV, to palm nut or to RPO as critical steps. Heating the RPO at 180-200°C appears as the more prejudicial step to VA. It decreased more than 70% and in less than 3 min, α-carotene, β-carotene and Retinol Activity Equivalent (RAE) contents. Violaxanthin, a non pro-VA carotenoid, was the only compound to be significantly affected by the thermal treatment (100°C) of amaranth leaves. RAE remained high after blanching even when alkaline traditional potash was added. The formulated sauces on the basis of the ingredients LV-amaranth, palm nut or RPO present a good acceptability, a high RAE and their consumption could be promoted favorably in food-based strategies to alleviate VAD.

Thesis (Ph.D. (Agricultural Economics )) -- University of Limpopo, 2021 / Regardless of the strategies adopted globally and nationwide to fight food insecurity within communities, particularly in the rural context, poverty becomes a major constituent which translates to most rural households experiencing food insecurity shocks. Given the high unemployment rate in South Africa which triggers several household’s vulnerability to food insecurity, the country has diverse natural resources which include indigenous plants such as Indigenous Leafy Vegetables (ILVs), which can be used as food and for business purposes by its residents. Irrespective of the diversity of ILVs in South Africa, there is a significant decline in the production and consumption of ILVs particularly in rural areas where these vegetables are mostly available. In addition, production and consumption of ILVs may not only address food insecurity but these vegetables may benefit households through the income obtained from their sales. The income generated from sales of ILVs may therefore assist towards improving and sustaining rural livelihood needs. Given this background information, the study aimed at assessing ILV production for income generation and food security among rural households in the Eastern Cape Province (ECP) of South Africa. The study was conducted within the three district municipalities of the ECP which were selected because statistics report these districts to be the most affected areas by poverty within the province. These districts are OR Tambo District Municipality (ORTDM), Alfred Nzo District Municipality (ANDM) and Joe Gqabi District Municipality (JGDM). Multistage and proportional random sampling procedures were employed to select households which could participate in the study. Thus, 407 households within these three (3) districts municipalities were used for the purposes of the study. The study also included interviewing role players within the ILV production value chain, thus a snowball sampling procedure was used to select role players. Sixteen hawkers and three input suppliers were interviewed from the three district municipalities. In addition, from the 407 households that were interviewed, 260 households from the three district municipalities reported to be producers of ILVs. A structured questionnaire was therefore used to collect pertaining data allied in achieving the aim of the study. The collected data was captured using Excel 2016, after data cleaning, it was then exported to Statistical Package for Social Sciences (SPSS) version 25 for analysis. Numerous analytical models were used from SPSS 25. For instance, to identify and describe socio-economic characteristics of households, to assess the most produced ILVs from the study areas and to identify role players within the ILV production value chain, descriptive statistics in a form of means, percentages, frequencies, and standard deviation was used. To determine factors which influence production of ILVs, a Binary Logistic Regression Model was used. A Multinomial Logistic Regression model was used to determine factors which influence different uses of ILVs by households and to determine factors influencing food security status among households. A gross margin analysis was used to estimate viability from each ILV produced, harvested and sold, while Household Food Insecurity Access Scale (HFIAS) was used to measure food security status among households. Lastly, a correlation matrix was also used to determine the relationship between the role players and their functions among the ILV production value chain. Based on the results, the study therefore concluded that, from the three district municipalities used in the study, there are various ILVs growing naturally and produced. The production of ILVs from these municipalities is habituated by socio economic characteristics of households, wherein households use ILVs for various purposes which include these vegetables as source of food, medicine and livestock feed. The use of ILVs among households is influenced by socio-economic characteristics and seasonal availability of ILVs in ORTDM, while in ANDM and JGDM, the use of ILVs by households is conditioned by socio-economic characteristics of households, knowledge/ awareness related to nutrition and health benefits of ILVs and seasonal production of ILVs. Furthermore, this research concludes that, ILVs have a potential of diversifying diets and addressing food insecurity problems within rural parts of the three districts. Given the positive gross margins from the three districts, production and selling of ILVs has a potential to contribute to rural household income. Lastly, the study concludes that, the ILV production value chain system lacks governmental support in the form of institutional engagement since there is no evidence of extension officer support from these three district municipalities concerning ILVs production. To this end, the study recommends that, policy makers should further establish inclusion of ILVs in both farming and food systems. Also, government and related institutions which focus on sustainable rural development must intervene in promoting production of ILVs particularly within rural contexts since production of these vegetables may alleviate poverty through job creation, addressing food insecurity and income generation. Thus, a successful intervention of government and policy makers in ILV production would have a potential of translating to sustainable rural livelihoods / National Research Foundation (NRF)

No description available.

[ES] En los cítricos, la baja temperatura promueve la inducción floral en otoño-invierno aumentando la expresión del gen promotor CiFT3 (homólogo en los cítricos del gen FLOWERING LOCUS T). La presencia de un gran número de frutos en el árbol durante ese momento inhibe la expresión de CiFT3 y la floración, pero se desconoce la señal inhibitoria que genera el fruto. Las hipótesis mayormente aceptadas proponen que la señal puede ser hormonal o nutricional. En el primer caso, el efecto inhibidor se atribuye a las hormonas que el fruto produce y exporta durante su desarrollo. En el segundo caso, el efecto inhibidor se atribuye a la alta demanda y consumo de carbohidratos por los frutos en desarrollo. Ambas hipótesis son complementarias y no excluyentes entre sí. Además, se ha demostrado que el fruto promueve la activación epigenética del represor de la floración CcMADS19 (homólogo en los cítricos del gen FLOWERING LOCUS C), que inhibe la expresión del gen CiFT3. Con el objetivo de determinar qué señal produce el fruto para inhibir la floración, en esta Tesis se propone la siguiente hipótesis: El fruto inhibe la floración a través de la síntesis y exportación de auxinas que activa la síntesis de giberelinas y, a su vez, la expresión de CcMADS19. Mediante experimentos con tratamientos exógenos de auxinas, giberelinas, y sus antagonistas, aclareo de frutos, y la interrupción del transporte por el floema entre el fruto y las yemas, los resultados indican que ni las giberelinas ni las auxinas se relacionan de forma consistente con la activación de la expresión de CcMADS19 en las hojas. En las yemas, las giberelinas se relacionan con la activación del gen inhibidor CENTRORRADIALIS (CEN), cuando hay fruto por aumento de la síntesis de GA4, y cuando no hay fruto por su aplicación exógena. La presencia del fruto aumenta la concentración de auxinas en el tallo y la yema en el momento de la inducción, y reprime su síntesis y trasporte. Pero esto no impide que, en la yema, el gen CcMADS19 esté epigenéticamente silenciado y que el silenciamiento se transmita a los nuevos brotes vegetativos. Estos brotes florecen en el siguiente ciclo, y, en sus yemas, la diferenciación floral se relaciona con un aumento de la síntesis y trasporte de auxinas y una reducción de la síntesis de giberelinas. / [CA] Als cítrics, les baixes temperatures promouen la inducció floral a la tardor i l'hivern augmentant l'expressió del gen promotor CiFT3 (homòleg en els cítrics del gen FLOWERING LOCUS T). La presència d'un gran nombre de fruita a l'arbre en aquest moment inhibeix l'expressió de CiFT3 i la floració, però es desconeix la senyal inhibidora que genera la fruita. Les hipòtesis majoritàriament acceptades proposen que la senyal pot ser hormonal o nutricional. En el primer cas, l'efecte inhibidor s'atribueix a les hormones que la fruita produeix i exporta durant el seu desenvolupament. En el segon cas, l'efecte inhibidor s'atribueix a la alta demanda i consum de carbohidrats per part de la fruita en desenvolupament. Ambdues hipòtesis són complementàries i no es descarten mútuament. A més, s'ha demostrat que la fruita promou l'activació epigenètica del repressor de la floració CcMADS19 (homòleg en els cítrics del gen FLOWERING LOCUS C), que inhibeix l'expressió del gen CiFT3. Amb l'objectiu de determinar quina senyal produeix la fruita per inhibir la floració, en aquesta Tesi es proposa la següent hipòtesi: La fruita inhibeix la floració mitjançant la síntesi i exportació d'auxines que activa la síntesi de giberelines i, al seu torn, l'expressió de CcMADS19. Mitjançant experiments amb tractaments exògens d'auxines, giberelines i els seus antagonistes, aclarida de fruita i la interrupció del transport pel floema entre la fruita i les brots, els resultats indiquen que ni les giberelines ni les auxines es relacionen de manera consistent amb l'activació de l'expressió de CcMADS19 a les fulles. A les gemmes, les giberelines es relacionen amb l'activació del gen inhibidor CENTRORRADIALIS (CEN) quan hi ha fruita per l'augment de la síntesi de GA4 i quan no hi ha fruita per la seua aplicació exògena. La presència de la fruita augmenta la concentració d'auxines a la tija i la gemma en el moment de la inducció i reprimeix la seua síntesi i transport. Però això no impedeix que, a la gemma, el gen CcMADS19 estigui epigenèticament silenciat i que el silenciament es transmeti als nous brots vegetatius. Aquests brots floreixen al següent cicle i, a les seues gemmes, la diferenciació floral es relaciona amb un augment de la síntesi i transport d'auxines i una reducció de la síntesi de giberelines. / [EN] In citrus, low temperature promotes flower induction in autumn-winter by increasing the expression of the CiFT3 promoter gene (citrus homologue of the FLOWERING LOCUS T gene). The presence of large numbers of fruits on the tree at this time inhibits CiFT3 expression and flowering, but the inhibitory signal produced by the fruits is unknown. The most widely accepted hypotheses are that the signal is hormonal or nutritional. In the first case, the inhibitory effect is attributed to hormones produced and exported by the fruit during development. In the second case, the inhibitory effect is attributed to the high demand and consumption of carbohydrates by the developing fruit. The two hypotheses are complementary and not mutually exclusive. In addition, it has been shown that the fruit promotes the epigenetic activation of the flowering repressor CcMADS19 (citrus homolog of the FLOWERING LOCUS C gene), which inhibits the expression of the CiFT3 gene. To determine which signal is produced by the fruit to inhibit flowering, the following hypothesis is proposed in this thesis: The fruit inhibits flowering through the synthesis and export of auxins, which activates the synthesis of gibberellins and, in turn, the expression of CcMADS19. Experiments with exogenous treatments of auxins, gibberellins and their antagonists, fruit thinning, and disruption of phloem transport between fruit and buds indicate that neither gibberellins nor auxins are consistently associated with the activation of CcMADS19 expression in leaves. In buds, gibberellins are associated with the activation of the flowering inhibitor CENTRORADIALIS (CEN), in the presence of fruit by increasing GA4 synthesis, and in the absence of fruit by its exogenous application. The presence of fruit increases the concentration of auxin in the stem and bud at the time of induction and suppresses its synthesis and transport. However, this does not prevent the epigenetic silencing of the CcMADS19 gene in the bud, which is transmitted to the leaves of the new vegetative shoots. These shoots flower in the following cycle, where floral differentiation is associated with an increase in auxin synthesis and transport and a decrease in gibberellin synthesis in the bud. / Marzal Blay, A. (2024). Study of the Fruit Inhibitory Mechanism on Citrus flowering. Nutritional, Hormonal and Genetic Factors [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203155

The biofuel market is dominated by ethanol and biodiesel derived from cellulosic and lipid-based biomass crops. This is largely due to the relatively low costs and reliability of production. At present, production of non-food plant-derived oils for biofuel production in the U.S. is minimal. A research team from the Commonwealth Scientific and Industrial Research Organization (CSIRO), an independent Australian federal government research institution, has developed an efficient transgenic system to engineer oil production in tobacco leaves. This novel system is comprised of multiple transgenes that direct the endogenous metabolic flux of oil precursors towards triacylglycerol (TAG) production. Additional genes were incorporated to store and protect the accumulated oil in vegetative tissues. Preliminary greenhouse tests by the CSIRO research group indicated an oil content of > 30% by dry weight (DW) in tobacco leaf lamina. Here we evaluated two transgenic lines against a non-transgenic control in 2017 and 2018 in greenhouse and field production systems. The 2017 pilot study showed that the high leaf-oil tobacco line was viable and will grow in the field in Kentucky. Chemical analyses revealed significantly higher oil content compared to the non-transgenic control despite several logistical setbacks. These promising discoveries prompted the deployment of additional transgenic line assessments and further data validation in 2018. Line evaluations in 2018 revealed that the LEC2:WRI1:DGAT:OLE transgenic line had the highest leaf oil content (≥ 19.3% DW-1) compared to both the WRI1:DGAT:OLE transgenic line (≤ 5.6% DW-1) and non-transgenic control (≤ 2.1% DW-1). The results of this research will contribute to the successful development of transgenic tobacco lines engineered to accumulate high concentrations of TAG in the leaves.

Douglas-fir (Pseudotsuga menziesii) is an economically important softwood that is clonally propagated for reforestation purposes by somatic embryogenesis. The molecular basis of embryogenesis in conifers is largely unknown and this prevents progress in somatic embryogenesis protocols. In angiosperms, the LEAFY COTYLEDON1 (LEC1) gene, encoding the HAP3 subunit of the eukaryotic CCAAT box-binding factor, is important in embryo formation, and necessary for somatic embryogenesis. A candidate gene strategy was employed to isolate the Douglas-fir LEC1 homologue, PmLEC1, via the polymerase chain reaction (PCR) with degenerate primers based on the Arabidopsis conserved domain, and the full-length cDNA sequence was obtained by rapid amplification of cDNA ends-PCR (RACE-PCR). The putative protein sequence shared high sequence identity with Arabidopsis LEC1. Northern analysis and quantitative real-time PCR indicate that this is an embryo-specific gene, expressed with the highest abundance during early embryogenesis. Antibodies were raised against a synthetic 18-amino acid PmLEC1 peptide, and in contrast to mRNA expression, Western blotting shows that PmLEC1 protein expression persists until the seedling stage. To gain insight into modulation of PmLEC1 expression and its inducibility in mature tissues, stress and hormone treatments were performed on mature seed and the promoter sequence was isolated by genome walking. Sorbitol, mannitol and 2,4-epibrassinolide were found to significantly up-regulate PmLEC1 expression. The PmLEC1 promoter contains a 5’ UTR intron with numerous enhancer elements, and factors that bind to these elements mediate responses to auxin, UV light and developmental cues, osmotic stress, biotic stress, and tissue culture. Some of the regulatory elements are binding sites for seed-specific transcription factors that are well known from angiosperms, providing new evidence that AGL15, ABI3 and VP1 proteins have a direct role on LEC1 expression. In investigating the embryogenic capacity of PmLEC1, ectopic expression of PmLEC1 in the embryo lethal Arabidopsis lec1-1 null mutant complemented the mutation and permitted the production of viable, desiccation tolerant seeds. In addition, transgenic seedlings produced embryo-like structures from vegetative organs and expressed seed-specific genes. In wild type plants, ectopic expression of PmLEC1 resulted in a bushy phenotype but expression of seed-specific genes was not observed. Taken together, these results show that PmLEC1 is an embryo-specific gene with an essential role throughout embryogenesis, and PmLEC1 expression may be induced in mature seeds by stress and hormone treatments. Because mature seeds show only trace amounts of PmLEC1 transcripts and Douglas-fir somatic embryogenesis can only be induced from immature embryos, this information provides useful insight into initiation of embryogenesis from vegetative tissues. The identification of binding sites for transcription factors known from angiosperms in the promoter region of PmLEC1 has revealed the identity of several genes which are expected to play pivotal roles in conifer embryogenesis.

Rhodococcus fascians is a Gram-positive phytopathogenic bacterium which induces the development of leafy galls, local amplifications of multiple buds, on most infected plants. This process is linked to the production of phytohormones along with the presence of essential virulence-associated genes like the plasmid loci att and fas and the chromosomal gene vicA. However, the presence of these genes is not sufficient to ensure the infection phenotype development, indicating that other genes play a role in R. fascians pathogenicity. In this work, we studied the metabolic modifications occurring when the bacterium interacts with its host using a proteomic approach. A comparison between virulent and avirulent strains showed variations in the expression of catalases. In the virulent strain, besides the transitory induction of the att locus expression, the bacterium changes its metabolism from the Krebs cycle to the glyoxylate shunt, a process which is frequently observed in bacteria confronted to a hostile environment. The expression of the shunt-specific enzyme isocitrate lyase increased, while expression of fumarate hydratase and pyruvate dehydrogenase decreased. Hence, we focused on the link between the glyoxylate shunt and virulence. A screening of a R. fascians mutant library based on the capacity of bacteria to use acetate as the sole carbon source, a metabolic pathway depending on the glyoxylate shunt, resulted in the identification of a new gene essential for R. fascians pathogenicity. This gene encodes a glycosyl transferase, an enzyme known to be involved in the bacterial cell wall biosynthesis but possibly also implicated in cytokinin secretion. A mutant in this gene harboured an altered colony phenotype and could not induce malformations on infected plants. Accordingly, our results were integrated in the leafy gall pathology model recently presented by Stes et al. (2011). Finally, the several questions that are raised by this work, allowed us to suggest further research perspectives in order to unveil a little more of the R. fascians mysterious ways to interact with the plant./Rhodococcus fascians est une bactérie Gram-positive phytopathogène qui induit le développement de galles feuillées, des amplifications locales de multiples bourgeons, sur la plupart des plantes infectées. Ce processus est lié à la production de phytohormones ainsi qu’à la présence de gènes essentiels associés à la virulence tels que les loci plasmidiques att et fas et le gène chromosomique vicA. Cependant, la présence de ces gènes ne suffit pas à garantir le développement du phénotype d’infection, indiquant que d’autres gènes jouent un rôle dans la pathogénicité de R. fascians. Dans ce travail, nous avons étudié les modifications métaboliques qui se produisent lorsque la bactérie interagit avec son hôte par une approche protéomique. Une comparaison entre les souches virulente et avirulente a mis en évidence des variations d’expression au niveau des catalases. Dans la souche virulente, outre l’induction transitoire de l’expression du locus att, la bactérie change son métabolisme pour passer du cycle de Krebs au shunt du glyoxylate, un processus fréquemment observé chez les bactéries confrontées à un environnement hostile. L’expression de l’isocitrate lyase, enzyme spécifique au shunt, augmente, tandis que celle de la fumarate hydratase et de la pyruvate déhydrogénase diminue. Nous nous sommes donc intéressés au lien entre le shunt du glyoxylate et la virulence. Le screening d’une banque de mutants de R. fascians basé sur la capacité de la bactérie à utiliser l’acétate comme seule source de carbone, une voie métabolique dépendant du shunt du glyoxylate, a permis d’identifier un nouveau gène essentiel pour la pathogénicité de R. fascians. Ce gène code pour une glycosyl transferase, une enzyme impliquée dans la biosynthèse de la paroi bactérienne mais également dans la sécrétion des cytokinines. Un mutant dans ce gène présente un phénotype de colonie altéré et ne peut induire de malformations chez les plantes infectées. Finalement, nos résultats et les pistes d’interprétations que nous avons émisent nous permettent de compléter le modèle de l’interaction R. fascians-plante proposé récemment par Stes et al. (2011). Des perspectives de recherches visant une meilleure compréhension de ce pathosystème sont proposées. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Food insecurity remains a major challenge affecting the rural poor households in South Africa. The consumption of green leafy vegetables is important to address micronutrients deficiency in rural communities and, at the same time, it contributes to fibre intake. This study investigated the people’s attitude towards the cultivation and utilisation of ILVs in rural communities. A cross-section survey study was conducted among 1 000 respondents in randomly selected households in communities. The majority of respondents were not willingly consuming ILVs. This is because most consumers were black and of the low-income group. ILVs that are consumed grow mainly in the wild. The regular consumption of these vegetables as indicated in this study is interesting, as this will help in mitigating micronutrient deficiency. Furthermore, these vegetables could be incorporated in formulated food to improve iron and zinc, especially in infant foods formulation. Based on the findings of this study it would be important to find ways of encouraging cultivation of ILVs for both nutrition and as income generating activities. / Life and Consumer Science / M.CS.