Gethyllis multifolia L. Bolus and G. villosa Thunb. are winter-growing, summerblooming, deciduous and bulbous geophytes that grow naturally in the semi-arid succulent Karoo biome of South Africa. Both species grow under full sun conditions and have four distinctive growth phases: a winter (cold and wet) growing phase, leaf senescence phase towards spring, flowering phase during the hot and dry summer months, and fruit and leaf formation phase in autumn. The medicinal uses of this genus (including G. multifolia “Kukumakranka” and G. villosa “hairy kukumakranka”) range from cures for colic, digestive disturbances, teething problems, fatigue, boils, bruises and insect bites, to being used as an aphrodisiac. Gethyllis multifolia is threatened in its natural habitat and is listed in the ‘Vulnerable’ category of the ‘Red Data List of Southern African Plants’ and the ‘IUCN-World Conservation Union List of Plants’. The literature indicate that the habitats of both species are being exposed to drier conditions and is further threatened by the encroachment of invasive indigenous plant species. It is not known to which extent these factors may pose a threat to the existence of both species. The first objective of this investigation was to determine the costs of vegetative and reproductive growth during the seasonal life cycle of the plant, using carbon (C) and nitrogen (N) as a physiological currency. The second objective was to elucidate a functional basis to explain the difference in the conservation status of both species in their natural habitat. Both species were subjected to drought and shading as environmental stresses and the plant physiological performance was investigated via photosynthetic gas exchange. The third objective of the study was to evaluate the antioxidant content (total polyphenol, flavonol/flavone and flavanone content) and antioxidant capacity [ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC) and 2,2'-azino-di-3- ethylbenzthiazoline sulphonate (ABTS) radical cation scavenging ability] of natural populations and plant samples that were exposed to photo- and -drought environmental stresses. This study was done to elucidate the antioxidant profile of plant parts of natural populations as well as providing farmers, traditional healers and pharmaceutical companies with cultivation environmental conditions to enhance the antioxidant properties of the species. This investigation also attempted to isolate and characterize, by means of thin-layer chromatography (TLC) and column chromatography (CC), natural compounds from both species to lend support to the purported antioxidant benefit of both species and to further lend support to claims made by traditional healers of the medicinal potential of the genus. This study, however, did not engage in any in vivo studies or human trials to support published literature of the medicinal benefits of the genus. The photosynthetic adaptation studies indicated that G. villosa had a better photosynthetic performance than G. multifolia during both drought and low light conditions because of the inability of G. multifolia to adapt to a wider range of environmental extremes. The C and N cost of growth and reproduction studies revealed that G. villosa had a more efficient resource utilisation strategy for both growth and reproduction. These physiological responses suggest that G. villosa, in general, has a more efficient survival strategy and that G. multifolia will struggle to adapt to drier environmental conditions, as well as growing in the shade of encroaching invasive plant species. To conclude, this could be a contributing factor as to why G. multifolia is threatened in its natural habitat and G. villosa not. The antioxidant content-and -capacity study on natural populations of both species revealed the highest total polyphenol content, FRAP and ORAC values for the flowers and fruits of G. multifolia and G. villosa compared to other plant parts. These values were found to be in line with and in some cases higher than most commercial fruits and vegetables. The antioxidant activity during drought and photo-stress of the leaves, bulbs and roots was found to be highest in the roots of both species during drought stress. Gethyllis multifolia, in general, exhibited higher total polyphenol content than G. villosa, with the highest content measured during drought stress in the roots of G. multifolia. Phytochemical investigation of the leaves, bulbs and roots of G. multifolia and G. villosa revealed the presence of tannins, flavonoids, phenolics, saponins, glycosides as well as essential oils, while alkaloids were absent. The chromatographic profiles of the leaves, bulbs and roots of both species further indicated that the roots of G. multifolia contained the highest concentration of natural products, compared to G. villosa and other plant parts. Further in-depth studies on the roots of G. multifolia led to the isolation and characterization of three known flavonoids, of which one was also isolated as its endogenously acetylated derivative. In contrast to the fact that both species had a high polyphenol content and exhibited high antioxidant activity, the isolated compounds in this study revealed very low antioxidant activity. However, the literature revealed that some of these isolated compounds exhibit antifungal, antibacterial, antiangiogenic and anticarcinogenic properties in vitro, which could be ascribed to the medicinal applications of plant parts of certain species belonging to this genus. Furthermore, this study suggests that further chemistry and pharmaceutical research on the genus, Gethyllis, in specific the flowers and fruit of these two species, be pursued. / Philosophiae Doctor - PhD

Diss. (sammanfattning Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Thesis (MSc (Forest and Wood Science))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: This study investigated the use of carbon isotopes as a potential measure for water availability and drought stress in Pinus radiata in the Western and Southern Cape, South Africa. An understanding of water availability and its variation in space is fundamental to the implementation of increasingly site-specific management regimes that have the potential to greatly improve productivity across sites in the region. Fifteen plantation compartments situated on water shedding sites were identified where good weather data existed and a water balance model could be run. In addition, late wood samples were analysed from four co-dominant trees in the same stand to determine the δ13C values of five tree rings, each representing a specific growth year before first thinning. Detailed water balances were constructed for each trial site and drought stress indicators (a) relative canopy conductance (after Granier et al., 2000) and (b) the ratio of actual to potential evapotranspiration (supply / demand ratio), were related to δ13C values in latewood. Maximum available soil water ranged from 52 to 313 mm across trial sites. The water balance model used adequately described soil water availability throughout each growing season and indicated that stand stress due to the lack of available soil water mainly occurred during the summer months of the study period (November to April). The supply / demand ratio for this period as well as the relative canopy conductance proved to be good measures of drought stress. The six-month supply demand ratio (calculated for the period November to April) ranged from 0.04 to nearly 1 (winter rainfall zone) and 0.35 to 1 (all-year rainfall zone) and were strongly related to δ13C values (p < 0.001; r2 = 0.7822). It appears that using δ13C values, it may be possible to classify sites into three water availability classes. This classification may assist in the implementation of intensive silvicultural operations on an increasingly site-specific basis. Where sites are enriched with water from lateral flow or upslope positions, δ13C may be the only reliable technique to quantify soil water availability. / AFRIKAANSE OPSOMMING: Hierdie studie ondersoek die gebruik van koolstof isotope as 'n moontlike maatstaf vir die beskikbaarheid van water en droogtestremming in Pinus radiata in die Wes-en Suid-Kaap, Suid-Afrika. 'n Begrip van die beskikbaarheid van water en die ruimtelike variasie daarvan is fundamenteel vir die implementering van groeiplek-spesifieke bestuur sisteem wat die potensiaal het om baie verbeterde produktiwiteit oor persele in die streek teweeg te bring. Vyftien plantasievakke, geleë op waterskeidingsterreine is geïdentifiseer waar goeie weer data bestaan en 'n water balans model uitgevoer kon word. Daarmee saam is laathout monsters vanuit vier ko-dominante bome in dieselfde kompartement geanaliseer en die δ13C waardes van laathout in vyf jaarringe bepaal wat elk 'n spesifieke jaar van groei voor die eerste dunning verteenwoordig. Gedetailleerde water balanse is vir elke proef perseel bereken en aanwysers van droogtestremming, nl.: (a) relatiewe kroon geleiding (na Granier et al., 2000) en (b) die verhouding van die werklike teenoor potensiële evapotranspirasie (vraag / aanbod verhouding) is gekorreleer met 13C waardes in laat hout. Die maksimum hoeveelheid water beskikbaar op die verskeie proefpersele wissel van 52 tot 313 mm. Die water balans model wat gebruik is beskryf die beskikbare grondwater met genoegsame akkuraatheid. vir die hele groeiseisoen. Die model dui ook aan dat die kompartemente droogtestremming as gevolg van die gebrek aan beskikbare grond water ervaar gedurende die somer maande van die studie tydperk (November tot April). Die vraag / aanbod verhouding vir hierdie tydperk, asook die relatiewe kroon geleiding is geskik om as maatstawwe van droogtestremming gebruik te word. Die vraag / aanbod verhouding (bereken vir die tydperk November tot April) het gewissel van 0,04 tot byna 1 (Winter reënval gebied) en 0,35 tot 1 (die heel jaar reënval sone) en is sterk verwant aan 13C waardes (p <0,001; r2 = 0,7822). Dit blyk dat met die gebruik van δ13C waardes, dit moontlik kan wees om kompartemente te klassifiseer in drie klasse van water beskikbaarheid. Hierdie klassifikasie kan help met die implementering van intensiewe boskultuur bedrywighede op 'n meer vak-spesifieke basis. Waar vakkeverryk is met water vanuit laterale vloei of hoër liggende posisies, mag δ13C dalk die enigste betroubare tegniek wees om die beskikbaarheid van water te kwantifiseer.

Made available in DSpace on 2016-12-06T17:42:04Z (GMT). No. of bitstreams: 1 PGPV14DA003.pdf: 1314776 bytes, checksum: 33cbd8345743a2328a15d9b823b1b1da (MD5) Previous issue date: 2014-08-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The effects of drought stress on growth and biomass partitioning of plants depend on the intensity and duration of drought stress and when it occurs in the crop cycle. Besides, plant management adopted can influence the plant responses under conditions of low water availability. The aim of this study was to evaluate the effects of drought stress on the growth and biomass partitioning of soybean in different growth stages. Four experiments were carried in greenhouse conditions. The first work evaluated changes in growth of soybean subjected to drought stress during reproductive development stages. This experiment was performed with NS 4823 cultivar subjected to drought stress for 10 days (without water) during R1 to R7 reproductive phenologic stages. In the end period of pea formation and grain filling of plants in drought stress the relative water content wasn t kept and stature growth rates, leaf area and node numbers were reduced. The lower sensitivity to drought stress in reproductive stage was related to the ability to maintain the relative water content in leaves and to increase root/shoot ratio. The second experiment determined the responses in morphology and partition of assimilate in soybean subjected to drought stress during reproductive stages. This work was conducted with two cultivars, BMX Magna and BMX Potência RR, subjected to drought stress for 10 days (without water) during R1 to R7 phenologic stages. The drought stress in the end of reproductive stages, such as pod formation and grain filling, reduces the sink strength because reduces pod and grain numbers, and reduces the source strength due to reduced shoot dry mass. The aim of third experiment was to evaluate if the use of gypsum would be effective to reduce drought stress effects in grain filling. This experiment was conducted with NA 5909 RR cultivar subjected to drought stress and gypsum doses of 0 and 6 Mg ha-1 on surface and 6 Mg ha-1 incorporated. In soils with low aluminum concentration the gypsum was effective to reduce drought stress in R5 stage of soybean, because promotes root growth on subsurface through increasing in calcium and decreasing in aluminum concentrations. The aim of fourth experiment was evaluate if K would be effective in drought stress mitigation during begging vegetative development. This experiment was conducted with BMX Turbo RR cultivar subjected to drought stress for 12 days and K doses of 0, 30 and 60 mg dm-3. Early K supplementation on soybean developmental stages increased drought stress tolerance through increasing in root length density and root specific mass / Os efeitos da restrição hídrica no crescimento e na partição de biomassa das plantas dependem da intensidade e duração do período de restrição hídrica e do momento em que ocorre no ciclo da cultura. Além disso, o manejo adotado na cultura pode influenciar nas respostas da planta sob condições de baixa disponibilidade hídrica. O presente trabalho teve como objetivo avaliar os efeitos da restrição hídrica no crescimento e partição de biomassa da soja em diferentes estádios de desenvolvimento. Para isso, foram realizados quatro experimentos conduzidos em casa de vegetação. O primeiro trabalho avaliou as alterações no crescimento da soja submetida à restrição hídrica nos estádios reprodutivos do desenvolvimento. Este experimento foi realizado com a cultivar NS 4823 RR submetida à restrição hídrica imposta por 10 dias (sem irrigação) iniciando-se sempre em cada um dos estádios fenológicos reprodutivos desde R1 ao R7. No período final de formação de vagens e no enchimento de grãos das plantas em restrição hídrica o conteúdo relativo de água na folha não foi mantido e as taxas de crescimento de estatura, área foliar e número de nós foram reduzidos. A menor sensibilidade nos estádios iniciais do desenvolvimento reprodutivo a restrição hídrica foi relacionada à capacidade de manter o conteúdo relativo de água nas folhas e aumentar a relação raiz parte aérea. O segundo experimento determinou as respostas na morfologia e na partição dos assimilados na soja submetida à restrição hídrica nos estádios reprodutivos. O experimento foi realizado com duas cultivares, BMX Magna e BMX Potência RR, submetidas à restrição hídrica imposta por 10 dias (sem irrigação) nos estádios fenológicos de R1 a R7. A restrição de água no período final de formação de vagens e enchimento de grãos reduz a força de dreno, pois reduz o número de vagens e de grãos, e reduz a força de fonte devido à redução da massa seca de parte aérea. O terceiro experimento teve com o objetivo determinar se o uso do gesso seria efetivo na redução dos efeitos da deficiência hídrica no enchimento de grãos. O experimento foi realizado com a cultivar NA 5909 RR submetida a restrição hídrica e as doses de gesso 0 Mg ha-1, 6 Mg ha-1 na superfície e 6 Mg ha-1 incorporado. Em solos com baixa concentração de alumínio o gesso foi efetivo na redução da deficiência hídrica no estádio R5, pois promove o crescimento radicular em subsuperfície através do incremento nas concentrações de cálcio e redução no alumínio. O quarto experimento objetivou determinar se o K seria efetivo na mitigação da restrição hídrica no início do desenvolvimento vegetativo. O experimento foi realizado com a cultivar BMX Turbo RR submetida à restrição hídrica por 12 dias e a doses de 0 mg dm-3, 30 mg dm-3 e 60 mg dm-3 de K. A suplementação precoce de K no desenvolvimento da soja aumentou a tolerância à restrição hídrica, através do aumento da densidade de comprimento de raiz e do peso específico de raiz

Chez Arabidopsis thaliana, les protéines SIAMESE-RELATED (SIM/SMR1 à 13) forment une famille plante-spécifique d’Inhibiteurs de Kinase Cycline-dépendante (CKI), homologue des Kip-Related Proteins. SIM et SMR1 sont des régulateurs positifs de la transition du cycle mitotique vers l’endoréplication. L’expression des gènes SIM/SMR est induite en réponse àdes stress. L’un des stress abiotiques majeurs pour les plantes est la sécheresse. Les SIM/SMR pourraient être dégradées par la voie de la protéolyse spécifique de l’Ubiquitin Proteasome System (UPS). Les SIM/SMR sont de bons candidats pour relier l'activité du cycle cellulaire aux stimuli de l'environnement. Ce travail a démontré l’implication de la protéolyse UPS dans le contrôle posttraductionnel de tous membres SIM/SMR testés. Il démontre que SIM, SMR2 et SMR1 sont nécessaires à l’endoréplication des cellules foliaires. Lors d’un stress hydrique, l’expression des gènes SIM, SMR1, SMR3 et SMR5 est induite. Le profil spatio-temporel de ces inductions a mis en évidence deux groupes de gènes avec des fonctions distinctes. Les mutants sim, smr5 et sim.smr1.smr2 sont hypersensibles au stress hydrique. / In Arabidopsis thaliana, the SIAMESE-RELATED proteins (SIM/SMR1 to 13) are a plantspecific family of Cyclin-dependent Kinase Inhibitors (CKIs), homologous to the Kip-Related Proteins. SIM and SMR1 are positive regulators of the switch from mitotic cycle to endoreplication. The expression of SIM/SMRs genes is induced in response to stress. One of the major abiotic stress for plants is the drought stress. The SIM/SMRs could be degraded through the specific proteolysis of Ubiquitin Proteasome System (UPS). The SIM/SMRs proteins are good candidates to link cell cycle activity with environmental stimuli.This research work has shown the involvement of the UPS proteolysis in the posttranslational control of all the tested members of the SIM/SMR family. It also shows that SIM, SMR2 and mostly SMR1 are required in endoreplication of leaf cells. During drought stress, the expression of SIM, SMR1, SMR3 and SMR5 genes is induced. The spaciotemporal pattern of those inductions revealed two groups of genes with distinct functions. In addition, the sim, smr5 and sim.smr1.smr2 loss-of-function mutants tested are hypersensitive to drought stress.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2018-07-03T12:48:47Z No. of bitstreams: 2 Dissertação - Karinne Evaristo de Deus - 2014.pdf: 3544531 bytes, checksum: a66cafd69f531c94042afb6432fd61cd (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-07-03T15:28:10Z (GMT) No. of bitstreams: 2 Dissertação - Karinne Evaristo de Deus - 2014.pdf: 3544531 bytes, checksum: a66cafd69f531c94042afb6432fd61cd (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-07-03T15:28:10Z (GMT). No. of bitstreams: 2 Dissertação - Karinne Evaristo de Deus - 2014.pdf: 3544531 bytes, checksum: a66cafd69f531c94042afb6432fd61cd (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-06-30 / Drought is a major cause for reduced productivity in the cultivation of upland rice farming in many regions of the world. One of the consequences of the drought is the production in excess of reactive oxygen species (ROS), causing a series of oxidative damage to various biomolecules with subsequent cell death. With the function of protecting structures and functioning of cells from the damaging effects of ROS, a complex antioxidant system is activated in plants. This system consists of: (1) lipid soluble membrane-associated and tocopherols; (2) reducing water soluble compounds such as ascorbate (ASA) and glutathione (GSH) and (3) antioxidative enzymes, and superoxide dismutase (SOD) considered as a major enzymes of the antioxidant defense system. The present study aimed to evaluate the SOD in activity level via spectrophotometric method and level of gene expression via qPCR in two genotypes of upland rice (Oryza sativa japonica), Douradão and BRS Primavera, with contrasting for drought tolerance characteristics, watching the leaf and root tissue, two stages of plant development (vegetative and reproductive), grown under optimal water conditions and water deficit (100% and 50% water in the vessels), respectively. The results revealed a differential pattern of SOD activity in different tissues and developmental stages in tolerant and sensitive genotypes, and for the tolerant genotype that activity was increased only in leaf / root and vegetative/reproductive tissue, as was sensitive the leaf / reproductive and reproductive/ root. Regarding gene expression, we also observed a very different pattern of regulation in tolerant and sensitive genotypes. The CuZnSOD1, CuZnSOD4, and MnSOD genes, expression was significantly (p≤ 0.05) increased in the tolerant, the first in leaves and roots off the reproductive stage, the second vegetative stage only in leaves and the third gene in the two tissues and plant developmental stages. As for the sensitive only FeSOD1 gene had highlighted with increased expression in roots at the reproductive stage. Certainly, the different patterns of induction level of activity and / or gene expression of SOD in plants of upland rice, should be strongly considered to elucidate the cellular mechanisms of drought tolerance, aiming to support improvement programs to develop cultivars more efficient and better suited to prone areas with water deficiency. / A seca é uma das principais causas para redução da produtividade na cultura do arroz de terras altas em muitas regiões agrícolas do mundo. Uma das consequências da seca é a produção, em excesso, de espécies reativas de oxigênio (EROs), podendo causar uma série de danos oxidativos a diversas biomoléculas com consequente morte celular. Com a função de proteger estruturas e funcionamento das células dos efeitos prejudiciais das EROs, um complexo sistema antioxidativo é ativado nas plantas. Esse sistema é constituído de: (1) lipídeos solúveis e tocoferóis associados à membrana; (2) compostos redutores solúveis em água, tais como ascorbato (ASA) e glutationa (GSH), e (3) enzimas antioxidativas, sendo a superóxido dismutase (SOD) considerada como uma das principais enzimas do sistema de defesa antioxidativo. O presente estudo teve como objetivo avaliar a SOD, em nível de atividade via método espectrofotométrico e em nível de expressão gênica via qPCR, em dois genótipos de arroz de terras altas (Oryza sativa japonica), Douradão e BRS Primavera, com características contrastantes para tolerância à deficiência hídrica, contemplando parte aérea e tecido radicular, dois estádios de desenvolvimento das plantas (vegetativo e reprodutivo), cultivadas sob condição hídrica ótima e de deficiência hídrica (100 % e 50 % de água nos vasos), respectivamente. Os resultados revelaram um padrão diferencial de atividade da SOD nos diferentes tecidos e estádios de desenvolvimento nos genótipos tolerante e sensível, sendo que para o genótipo tolerante essa atividade foi aumentada somente em tecido foliar fase vegetativa e radicular fase reprodutiva, enquanto no sensível foi foliar e radicular estádio reprodutivo. Quanto à expressão gênica, também observou um padrão bastante diferenciado de regulação nos genótipos tolerante e sensível. Os genes Cu/ZnSOD1, Cu/ZnSOD4 e MnSOD apresentaram expressão significativamente (p ≤ 0,05) aumentada no tolerante, sendo o primeiro em folhas e raízes do estádio reprodutivo, o segundo estádio vegetativo somente em folhas e para o terceiro gene nos dois tecidos e estádios de desenvolvimento da planta. Já para o genótipo sensível somente o gene FeSOD1 apresentou destaque com aumento da expressão em raízes no estádio reprodutivo. Certamente, os diferentes padrões de indução em nível de atividade e/ou expressão gênica da SOD, em plantas de arroz de terras altas, devem ser fortemente considerados para elucidar os mecanismos celulares de tolerância à seca, objetivando subsidiar programas de melhoramento para desenvolvimento de cultivares mais eficiente e mais bem adaptada às áreas propensas à deficiência hídrica.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O cloroplasto à uma organela caracterÃstica dos organismos fotossintetizantes sendo seu papel primordial na geraÃÃo de energia a partir de gÃs carbÃnico e Ãgua. Essa organela pode ter seu funcionamento comprometido quando submetida a estresses ambientais devido a fragilidade e complexidade do sistema. Para evitar perdas provocadas pelo estresse existem vÃrios mecanismos de adaptaÃÃo e regulaÃÃo das reaÃÃes que ocorrem no cloroplasto. Recentemente caracterizou-se mais um desses provÃveis mecanismos que foi chamado de clororespiraÃÃo. A clororespiraÃÃo foi esclarecida com a descoberta de uma enzima similar a oxidase alternativa da mitocondria que chamou-se de oxidase terminal do plastÃdeo (PTOX). A funÃÃo dessa respiraÃÃo do cloroplasto permanece incerta, mas uma das hipÃteses mais aceitas à que o funcionamento da clororespiraÃÃo poderia prevenir a formaÃÃo de espÃcies reativas de oxigÃnio atravÃs da reciclagem dos intermediÃrios redutores do cloroplasto. No presente trabalho foi caracterizado a presenÃa de dois genes que codificam para a oxidase terminal do plastÃdeo em plantas de Zea mays. Estudou-se tambÃm a expressÃo diferencial de ambos genes da PTOX em resposta ou estresse hÃdrico, alÃm da caracterizaÃÃo da clororespiraÃÃo atravÃs da atividade da NADH desidrogenase plastidial (NDH) em gel de poliacrilamida. A caracterizaÃÃo molecular dos genes da PTOX mostrou homologia de 60% quando comparadas as sequÃncias dos genes e de 79% quando comparadas as prÃ-proteÃnas traduzidas. Os genes dessa proteÃna tÃm estruturas similares, sendo compostos por oito introns e 9 Ãxons. Um estudo das regiÃes dos promotores dos genes mostrou que existiam elementos comuns porÃm a presenÃa de elementos diferentes como, o elementos cis MBS que à responssivo à seca, poderia revelar uma regulaÃÃo diferencial dos genes. A resposta diferencial foi confirmada atravÃs de RT-PCR semiquantitativo. O gene chamado de ptox1 teve sua expressÃo estÃvel, podendo ser considerado um gene constitutivo, enquanto que o gene chamado de ptox2 teve um aumento da expressÃo proporcional ao estresse aplicado tanto em folhas como em raÃzes de plantas de milho. A anÃlise da atividade da NDH em gel (zimograma) revelou a presenÃa dessa enzima em cloroplastos de milho confirmando a presenÃa das enzimas da clororespiraÃÃo. O estudo filogenÃtico de sequencias de cDNA de bancos de dados mostraram que milho e sorgo pertencentes ao grupo das monocotiledÃneas, sÃo espÃcies muito prÃximas e que compartilham dois genes ortÃlogos da PTOX identificados como ptox1 e ptox2. Concluiu-se pela primeira vez a presenÃa de dois genes da PTOX no genoma do milho, uma monocotiledÃena de metabolismo C4. Os genes foram denominados de ptox1 e ptox2. Eles foram encontrados em raÃzes e folhas e apenas o gene da ptox2 pareceu ser induzido em resposta ao estresse osmÃtico. / The chloroplast is an organelle characteristic of photosynthetic organisms and their role in generating energy from carbon dioxide and water. This organelle may be functionally compromised when subjected to environmental stress due to the fragility and complexity of the system. To avoid losses caused by stresses plants have evolved various coping mechanisms, as well as, regulation of the reactions that occur in the chloroplast. Most recently it was characterized one of these mechanisms that was called chlororespiration. The chlororespiration was bring to light with the discovery of an enzyme, similar to the alternative oxidase of mitochondria, that was called the plastid terminal oxidase (PTOX). The function of this chloroplast respiration remains uncertain, but one of the most accepted hypothesis is that the operation of chlororespiration could prevent the formation of reactive oxygen species by recycling the reducing intermediates of the chloroplast. The present study characterized the presence of two genes encoding the plastid terminal oxidase in plants of Zea mays., and its differential expression in response to water stress. It was also characterized the chlororespiration through the activity of plastidial NADH dehydrogenase (NDH) in polyacrylamide gel. The molecular characterization of PTOX genes showed 60% homology when compared sequences of genes, but 79% when compared to pretranslated proteins. The genes of this protein have similar structures, being composed of nine exons and eight introns. A study of regions of the promoters of the genes showed that there were common elements, but the presence of different elements such as the cis elements that MBS responsive to drought, could reveal a differential regulation of genes. The differential response was confirmed by semiquantitative RT-PCR. The gene called ptox1 had its expression level stable and could be considered a constitutive gene, while the gene called ptox2 had an increased expression proportional to the applied stress in both leaves and roots of maize plants. The analysis of NDH activity gel (zimograms) revealed the presence of this enzyme in maize chloroplasts suggesting the existence of the chlororespiratory pathway. The phylogenetic analysis of cDNA sequences from NCBI databases showed that maize and sorghum, being closely related species, share two genes )identified as orthologs of PTOX (ptox1 and ptox2). It was confirmed for the first time the presence of two PTOX genes in the genome of maize, a C4-metabolism monocotyledon and its differential expression under drought stress.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2015-04-20T14:13:50Z No. of bitstreams: 2 Dissertação - Gabriel Feresin Pantalião - 2103.pdf: 1079775 bytes, checksum: fb08083324cd3c94d9a60fd9eeddd83d (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-04-20T14:15:43Z (GMT) No. of bitstreams: 2 Dissertação - Gabriel Feresin Pantalião - 2103.pdf: 1079775 bytes, checksum: fb08083324cd3c94d9a60fd9eeddd83d (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-04-20T14:15:43Z (GMT). No. of bitstreams: 2 Dissertação - Gabriel Feresin Pantalião - 2103.pdf: 1079775 bytes, checksum: fb08083324cd3c94d9a60fd9eeddd83d (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-03-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Drought is an environmental factor which narrows crop production, such as upland rice (Oryza sativa L.). The knowledge of aspects related to drought stress, and plant response to it, may furnish plant breeding programs essential data for the development of tolerant cultivars, and hence with higher yields under such conditions. Association mapping has been a successful approach to elucidate the genetic basis of economically important traits in plants, and afterward in the implementation of marker assisted selection (MAS). Next-generation sequencing (NGS) technologies have been applied in a variety of contexts, including SNP identification and development. Among methodologies for marker discovery and high-throughput genotyping, GBS (Genotyping by Sequencing) points out by its low cost and speed at which samples can be analyzed. The aim of this work was to identify, by GBS, the polymorphism from SNP markers within 283 upland accessions from Embrapa Rice Core Collection (ERiCC) and associate them to yield under drought stress. After filtering the raw data of predetermined stringent parameters, 285.379 SNP were identified in the 12 rice chromosomes. For the association mapping, molecular and phenotypic data were combined for the identification of SNP associated to drought, aiming the subsequent development of a marker set for MAS besides the identification of genes for genetic engineering. The analysis identified 48 SNP associated with the evaluated traits, 13 associated to drought susceptibility index (DSI) and 35 to yield under drought stress. Among the 48 SNP, 35 was anchored in 31 rice genes. Seven genes, out of the 31, possessed SNP associated to DSI, and the other 24 genes to yield under drought stress. These genes may be evaluated to be effectively employed for MAS. If the overexpression of such genes provides an enhanced drought tolerance, they may be used in the development of tolerant rice cultivars. / A seca é um fator ambiental que limita a produção das culturas, como a do arroz de terras altas (Oryza sativa L.). O conhecimento de fatores envolvidos na tolerância à deficiência hídrica e das respostas das plantas a esse estresse podem fornecer subsídios aos programas de melhoramento para o desenvolvimento de cultivares tolerantes, e, consequentemente, com uma maior produtividade sob essas condições. O mapeamento associativo, ou análise de associação, tem sido aplicado com sucesso em plantas, sendo utilizado primeiramente na identificação de genes associados a caracteres de importância econômica, e posteriormente, na implementação de seleção assistida por marcadores (SAM). Tecnologias de sequenciamento de nova geração (NGS) têm sido recentemente utilizadas em projetos de sequenciamento e resequenciamento para identificar, validar e avaliar um grande número de SNPs, os quais podem ser utilizados em estudos de mapeamento associativo. Dentre os métodos desenvolvidos para a descoberta de marcadores moleculares e genotipagem de alto desempenho, destaca-se pela rapidez e baixo custo a genotipagem por sequenciamento (GBS). Esse trabalho objetivou detectar, via GBS, o polimorfismo de marcadores SNPs em 283 acessos de arroz de terras altas componentes da CNAE (Coleção Nuclear de Arroz da Embrapa) e associá-los à produtividade sob déficit hídrico. Após a filtragem dos dados brutos de acordo com parâmetros de estringência pré-definidos, foram contabilizados 285.379 SNPs distribuídos ao longo dos 12 cromossomos do arroz. As informações moleculares foram integradas aos dados fenotípicos derivados do experimento de avaliação de produtividade e Índice de Suscetibilidade à Seca (ISS), conduzido no ano de 2010 em Porangatu (GO) em ambiente com e sem deficiência hídrica, para possibilitar a análise de mapeamento associativo, e com isso, detectar marcadores SNPs relacionados à tolerância à seca e oportunizar o desenvolvimento de um conjunto de marcadores úteis para a seleção assistida para esse caráter, assim como genes para estudos de engenharia genética do arroz. Através da análise de associação, foram detectados 48 SNPs relacionados com os caracteres avaliados, dentre os quais 13 foram relacionados ao ISS e 35 à produtividade em condição de déficit hídrico. Dentre os 48 SNPs, foram identificados 35 SNPs ancorados em 31 genes de arroz. Dentre os genes identificados, sete deles continham SNPs associados ao ISS, enquanto que os restantes 24 genes continham SNPs associados à produtividade dos acessos em ambiente com deficiência hídrica. Esses genes podem ser avaliados para serem efetivamente utilizados na seleção assistida por marcadores. Adicionalmente, esses genes podem ser superexpressos para avaliar sua capacidade de aumentar a tolerância à seca, e em caso positivo, gerar cultivares comerciais de arroz geneticamente modificadas mais tolerantes a esse estresse.

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2016-10-06T18:12:15Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação Ellen Cristina Perin.pdf: 2710133 bytes, checksum: 106c3030cdbbdfb20e6ff087140c2245 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-10-11T20:47:01Z (GMT) No. of bitstreams: 2 Dissertação Ellen Cristina Perin.pdf: 2710133 bytes, checksum: 106c3030cdbbdfb20e6ff087140c2245 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-10-11T20:47:01Z (GMT). No. of bitstreams: 2 Dissertação Ellen Cristina Perin.pdf: 2710133 bytes, checksum: 106c3030cdbbdfb20e6ff087140c2245 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-02-24 / Sem bolsa / A biofortificação de culturas agrícolas é uma estratégia que vem sendo estudada e explorada com o objetivo de complementa r da alimentação pelo incremento ou melhoria na qualidade dos alimentos, visando reduzir a desnutrição e oferecer alimentos mais saudáveis. Dentre as técnicas utilizadas para realizar a biofortificação, o uso de fertilização e, mais recentemente, a aplicação de estresses abióticos controlados vem sendo abordadas, mostrando que as aplicações dessas técnicas podem acarretar no acúmulo de compostos com potencial antioxidante de interesse para promoção da saúde humana , sem prejudicar significativamente o desenvolvimento e produção das culturas. Os frutos de morango, cujas características sensoriais específicas vem promovendo aumento do seu consumo, apresentam naturalmente em sua composição compostos com potencial antioxidante, como vitamina C, compostos fenólicos e antocianinas os quais podem ter seus teores modificados de forma a melhorar seu potencial antioxidante, além de suas funções em condições de estresse como defesa. Por outro lado, o cultivo do morangueiro apresenta uma alta taxa de sensibilidade a déficits hídricos e nutricionais; a adubação empregada nessa cultura normalmente utiliza fontes solúveis de nutrientes minerais, que podem acarretar em prejuízos ao solo, desequilíbrio nutricional, lixiviação e contaminação de lençóis freáticos. Neste estudo, plantas de morangos foram submetidas a diferentes níveis de estresse hídrico e a uma adubação cuja matriz foi composta de torta de tungue e pós -derocha, efetuando-se avaliações de variáveis bioquímico-fisiológicas e moleculares. Os resultados mostraram que a adubação alternativa apresentou potencial para utilização como insumo agrícola, uma vez que aumentou a produção de frutos (23,79 % a mais que a adubação solúvel) tendo ainda proporcionado um maior acúmulo de compostos com potencial antioxidante nos frutos em comparação à adubação solúvel convencional (antocianinas, acúmulo relativo do transcrito UFGT e ácido L-ascórbico). A avaliação desta adubação alternativa em diferentes níveis de estresse hídrico demonstrou haver um maior incremento nos compostos fenólicos e atividade antioxidante, evidenciando a viabilidade desta estratégia de biofortificação, sendo que o nível 1 de estresse apresentou menores perdas em relação aos parâmetros fotossintéticos avaliados e redução da produção de frutos em relação ao nível de estresse mais severo avaliado (nível 2). Os resultados obtidos neste estudo corroboram o potencial de uso da adubação alternativa avaliada no cultivo do morangueiro, sendo necessária ainda a busca por um nível de estresse hídrico que além de incrementar compostos com potencial antioxidante, conforme observado neste estudo, não afete significativamente o desenvolvimento das plantas e a produtividade da cultura do morangueiro, bem como sirva como uma técnica eficaz de biofortificação. / The biofortification of crops is a strategy that has been studied and explored in order to improve feeding supply by increasing or improving food quality of food to reduce malnutrition and offer healthier foods. Among the techniques used to perform the biofortification, the use of fertilization and, more recently, the application of controlled abiotic stresses have been applied, showing that the application of these techniques may result in the accumulation of antioxidant compounds with potential interest for promotion of human health , without significantly harming crop development and productivity. The strawberry fruits , whose specific sensorial features make its increasingly high consumption, naturally present in its composition, with compounds with potential antioxidant such as vitamin C, phenolic acids and anthocyanins, which may have their contents modified in order to improve their antioxidant potential in addition to its defense functions under stress conditions. On the other hand, the strawberry crop has a high rate of sensitivity to water and nutritional deficits; main fertilizer strategies for this crop typically uses soluble sources of nutrients, which can result in soil damage, nutritional imbalance, leaching and contamination of groundwater. In this study, strawberry plants were subjected to different levels of water stress and to an alternative fertilizer matrix composed of tung presscake and rock powder, and evaluated to biochemical, physiological and molecular variables. The results showed that the alternative fertilization has potential for use as an agricultural input as long as it has increased the fruit yield (23.79 % related to the soluble fertilizer treatment) and also improved the accumulation of Lascorbic acid, anthocyanins and the related expression of the UFGT gene compared to the soluble fertilizer strategy. The evaluation of the same alternative fertilizer at two different levels of water stress showed a significant increase in total phenolic compounds and antioxidant activity, demonstrating the feasibility of this biofortification strategy. In the level 1 of drought stress the results showed an increase in the photosynthetic parameters and in the fruit productivity related to the more severe level of stress (level 2). The results of this study support the potential use of the alternative fertilization evaluated for the strawberry crop, although that remains necessary studies to find out drought stress level that besides increasing compounds with antioxidant potential, as observed in this study, do not affect significantly the plant growth and yield of strawberry crop, to be used as an biofortification technique.

Philosophiae Doctor - PhD / Gethyllis multifolia L. Bolus and G. villosa Thunb. are winter-growing, summer blooming, deciduous and bulbous geophytes that grow naturally in the semi-arid succulent Karoo biome of South Africa. Both species grow under full sun conditions and have four distinctive growth phases: a winter (cold and wet) growing phase, leaf senescence phase towards spring, flowering phase during the hot and dry summer months, and fruit and leaf formation phase in autumn. The medicinal uses of this genus (including G. multifolia "Kukumakranka" and G. villosa "hairy kukumakranka") range from cures for colic, digestive disturbances, teething problems, fatigue, boils, bruises and insect bites, to being used as an aphrodisiac. Gethyllis multifolia is threatened in its natural habitat and is listed in the 'Vulnerable' category of the 'Red Data List of Southern African Plants' and the 'IUCN-World Conservation Union List of Plants'. The literature indicate that the habitats of both species are being exposed to drier conditions and is further threatened by the encroachment of invasive indigenous plant species. It is not known to which extent these factors may pose a threat to the existence of both species. The first objective of this investigation was to determine the costs of vegetative and reproductive growth during the seasonal life cycle of the plant, using carbon (C) and nitrogen (N) as a physiological currency. The second objective was to elucidate a functional basis to explain the difference in the conservation status of both species in their natural habitat. Both species were subjected to drought and shading as environmental stresses and the plant physiological performance was investigated via photosynthetic gas exchange. The third objective of the study was to evaluate the antioxidant content (total polyphenol, flavonol/flavone and flavanone content) and antioxidant capacity [ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC) and 2,2'-azino-di-3- ethylbenzthiazoline sulphonate (ABTS) radical cation scavenging ability] of natural populations and plant samples that were exposed to photo- and -drought environmental stresses. This study was done to elucidate the antioxidant profile of plant parts of natural populations as well as providing farmers, traditional healers and pharmaceutical companies with cultivation environmental conditions to enhance the antioxidant properties of the species. This investigation also attempted to isolate and characterize, by means of thin-layer chromatography (TLC) and column chromatography (CC), natural compounds from both species to lend support to the purported antioxidant benefit of both species and to further lend support to claims made by traditional healers of the medicinal potential of the genus. This study, however, did not engage in any in viva studies or human trials to support published literature of the medicinal benefits of the genus. The photosynthetic adaptation studies indicated that G. villosa had a better photosynthetic performance than G. multifolia during both drought and low light conditions because of the inability of G. multifolia to adapt to a wider range of environmental extremes. The C and N cost of growth and reproduction studies revealed that G. villosa had a more efficient resource utilisation strategy for both growth and reproduction. These physiological responses suggest that G. villosa, in general, has a more efficient survival strategy and that G. multifolia will struggle to adapt to drier environmental conditions, as well as growing in the shade of encroaching invasive plant species. To conclude, this could be a contributing factor as to why G. multifolia is threatened in its natural habitat and G. villosa not. The antioxidant content-and -capacity study on natural populations of both species revealed the highest total polyphenol content, FRAP and ORAC values for the flowers and fruits of G. multifolia and G. villosa compared to other plant parts. These values were found to be in line with and in some cases higher than most commercial fruits and vegetables. The antioxidant activity during drought and photo-stress of the leaves, bulbs and roots was found to be highest in the roots of both species during drought stress. Gethyllis multifolia, in general, exhibited higher total polyphenol content than G. villosa, with the highest content measured during drought stress in the roots of G. multifolia. Phytochemical investigation of the leaves, bulbs and roots of G. multifolia and G. villosa revealed the presence of tannins, flavonoids, phenolics, saponins, glycosides as well as essential oils, while alkaloids were absent. The chromatographic profiles of the leaves, bulbs and roots of both species further indicated that the roots of G. multifolia contained the highest concentration of natural products, compared to G. villosa and other plant parts. Further in-depth studies on the roots of G. multifolia led to the isolation and characterization of three known flavonoids, of which one was also isolated as its endogenously acetylated derivative. In contrast to the fact that both species had a high polyphenol content and exhibited high antioxidant activity, the isolated compounds in this study revealed very low antioxidant activity. However, the literature revealed that some of these isolated compounds exhibit antifungal, antibacterial, anti angiogenic and anti carcinogenic properties in vitro, which could be ascribed to the medicinal applications of plant parts of certain species belonging to this genus. Furthermore, this study suggests that further chemistry and pharmaceutical research on the genus, Gethyllis, in specific the flowers and fruit of these two species, be pursued.