Fisiologia Vegetal

URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/185

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Data inicial: 2006Tem arquivos: SimAssunto: search.filters.subject.Fisiologia de Plantas Cultivadas

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    Características hidráulicas e fotossintéticas em espécies C3 e C4 proximamente relacionadas
    (Universidade Federal de Viçosa, 2023-08-01) Castro, Carolina Souza de; Martins, Samuel Cordeiro Vitor; http://lattes.cnpq.br/2674257594803408
    As plantas C4 são conhecidas por manter uma alta eficiência fotossintética e maior eficiência do uso da água em relação às espécies C3. No entanto, pouco se sabe sobre as diferenças nas relações hídricas entre os tipos fotossintéticos, principalmente em espécies pertencentes a grupos de transição entre os tipos C3 e C4. Este trabalho teve como objetivo explorar as características hidráulicas, anatômicas e fotossintéticas em espécies C3 (Tarenaya hassleriana (Th) e T. longicarpa (Tl)) e C4 (Gynandropsis gynandra (Gg)) relacionadas da família Cleomaceae. Nos parâmetros de relações hídricas, o teor relativo de água no ponto de perda de turgescência foi similar nas três espécies (0,89). As espécies Th e Gg apresentaram valores similares para o potencial osmótico em turgescência plena (-0,80 MPa), potencial hídrico no ponto de perda de turgor (-0,84 MPa) e na capacitância pré-perda de turgor (C PT , 1,30 mol m -2 MPa -1 ); no entanto, a C4 apresentou uma alta C PPT (6,28 mol m -2 MPa -1 ). As espécies Tl e Gg apresentaram taxas fotossintéticas semelhantes (22,35 µmol CO 2 m - s -1 ), porém a espécie C4 apresentou a menor razão entre a taxa de transporte de elétrons pela taxa fotossintética (5,95). Em relação à condutância hidráulica foliar, as três espécies obtiveram valores semelhantes. Por outro lado, as espécies C3 foram mais vulneráveis à cavitação do que a espécie C4, sendo que esta última apresentou a maior margem de segurança hidráulica. Com isso, a espécie C4 pode ser considerada como uma planta eficiente e segura do ponto de vista hidráulico, sugerindo que tal vantagem pode ter sido chave para a evolução em ambientes áridos. Palavras-chave: Eficiência hidráulica. Vulnerabilidade hidráulica. Eficiência do uso da água. Cleomaceae.
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    The role of abscisic acid and secondary growth on embolism resistance and drought tolerance in herbaceous plants
    (Universidade Federal de Viçosa, 2023-07-27) Haverroth, Eduardo José; Martins, Samuel Cordeiro Vitor; http://lattes.cnpq.br/5815345408533538
    Drought resistance is crucial for plant productivity in water-limited conditions. While the role of abscisic acid (ABA) in stomatal regulation is well-studied, its influence on hydraulic function beyond stomata remains understudied. Moreover, the impacts of secondary growth on xylem resistance are still poorly understood. In the first chapter, we aimed to elucidate the impact of ABA on drought-induced dysfunction by examining genotypes with divergent ABA accumulation abilities. All genotypes exhibited similar resistance to leaf and stem embolism and similar leaf hydraulic resistance. However, pronounced differences between extreme genotypes, sitiens (sit; a strong ABA- deficient mutant) and sp12 (a transgenic line with constitutive ABA over-accumulation) were observed. The water potential inducing 50% embolism was 0.25 MPa lower in sp12 compared to sit. Notably, plants with higher ABA levels (wild type and sp12) demonstrated significantly lower maximum stomatal conductance and minimum leaf conductance than ABA-deficient mutants. These variations in gas exchange were associated with ABA levels, stomatal density, and size. The elevated ABA content in plants resulted in decreased water loss, consequently leading to a delayed onset of lethal water potentials associated with embolism during drought stress. Therefore, the primary mechanism by which ABA enhances drought tolerance is through the regulation of water loss, thereby postponing the onset of dehydration and hydraulic dysfunction. In the second chapter, we focused on exploring the embolism resistance in the leaves, basal stems, and upper stems of two herbaceous species, Solanum lycopersicum and Senecio minimus, which undergo secondary growth in their mature stems. Our findings unveiled that the basal stem region with advanced secondary growth exhibited increased embolism resistance, leading to vulnerability segmentation between the basal stem and the remaining vegetative shoot. Alongside enhanced woodiness, embolism resistance in basal stems coincided with changes in anatomy and lignin content. Decreases in the pith-to-xylem area, increases in the proportion of secondary xylem conduits, and higher lignin content were observed in the basal stems. This study highlights the role of ABA in regulating drought tolerance by reducing waterloss and delaying hydraulic dysfunction. Additionally, it elucidates how secondary growth in herbaceous plants contributes to increased embolism resistance and ensures survival during drought periods while supporting the upper canopy. Keywords: Embolism. Cavitation. ABA. Solanum lycopersicum. Senecio minimus. Stomata. Xylem. Water deficit. Secondary growth. Lignin.
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    The genetic basis of drought resistance in tomato
    (Universidade Federal de Viçosa, 2022-04-08) Rosa, Bruno Luan; Zsögön, Agustin; http://lattes.cnpq.br/4339426814059763
    The development of crop varieties capable of maintaining satisfactory yields under stressful conditions such as drought is an important step towards ensuring adequate food production in the future. In this context, natural genetic variation in tomato can be allied with modern techniques such as the production of introgression lines, as well as mutant and transgenic organisms in the search for varieties more resistant to water deficit. Here, we show that S. pennellii introgression lines IL2-5, IL4-3, and IL2-5/4-3 exhibit increased leaf succulence, as well as significant changes in leaf thickness and stomatal density. Together, these leaf traits contributed to the maintenance of leaf water status, which improved photosynthetic performance and plant resilience when subjected to drought conditions. In this work, we also demonstrated the physiological and hydraulic changes caused by an allelic variant of the OBSCURAVENOSA (OBV) gene. In addition to controlling the development of vascular bundle sheath extensions (BSE), this gene also resulted in significant changes in leaf insertion angle, leaf margin serration, venation density, and fruit shape. We found that BSE development is strongly linked functionally to the auxin signaling network involving AUXIN RESPONSE FACTOR 4 (ARF4). Lastly, we show that loss of function of ARF4 alters leaf structure, resulting in a phenotype with severe leaf curling and low stomatal conductance. Loss of ARF4 function increased water and abscisic acid content in leaves, resulting in significant improvements in tomato plant resistance to salt and osmotic stress. Our data provide evidence that anatomical and morphological changes in leaves, whether from natural genetic variation or genetically modified organisms, can help to better understand the process of resistance to abiotic stress, such as drought and salinity. Thus, we suggest that mapping and identifying the genes responsible for the leaf traits demonstrated here may help in the creation of future varieties that are more resistant to water deficit. Keywords: Solanum pennellii. Introgression lines. Auxin. CRISPR-Cas9. Bundle sheath extensions. Drought stress.
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    Unraveling how an auxin signaling mutation affects the xylem hydraulic efficiency and safety in tomato
    (Universidade Federal de Viçosa, 2022-06-27) Andrade, Moab Torres de; Martins, Samuel Cordeiro Vitor; http://lattes.cnpq.br/1787541035821073
    Auxins are known to regulate xylem development in plants, however, their effects on water transport efficiency and hydraulic safety are poorly known. Here we used tomato plants of the diageotropica mutant (dgt), which has impaired function of a Cyclophilin 1 cis/trans isomerase involved in auxin signaling, and its corresponding wild type (WT), to explore its effects on plant hydraulics and leaf gas exchanges. The xylem conduits of dgt showed a reduced hydraulically-weighted vessel diameter (D h ) (24-43%) and conduit number (25-58%) in petioles and stems, resulting in lower theoretical hydraulic conductivities (K t ). On the other hand, no changes in root D h and K t were observed. In addition, the measured stem and leaf hydraulic conductances of dgt agreed with the K t values and were lower (up to 81%). Despite dgt and WT showing similar root D h and K t , the measured root hydraulic conductance of dgt was 75% lower. The dgt mutation increased the vein (D v ) and stomata density (D s ), which could potentially increase photosynthesis. Nevertheless, even presenting the same photosynthetic capacity of WT plants, the dgt showed a photosynthetic rate c. 25% lower, coupled with a stomatal conductance reduction of 52%. These results clearly demonstrate that increases in D v and D s only result in higher leaf gas exchange when accompanied by higher hydraulic efficiency. The dgt also showed higher wall thickness per conduit diameter ratio (t/b) 3 , without major modifications in the pit membranes and cell wall reinforcement. The changes in xylem architecture resulted in a more negative Ψ 50 (water potential of 50% loss hydraulic conductivity), with a difference of 0.25 MPa and an increase of 64% in hydraulic safety margin comparison with WT plants. Under water deficit, dgt took twice as many days to reach Ψ 50 (-1.34±0.06 MPa) and half the time after rehydration to recover gas exchange when compared with WT (Ψ 50 = -1.14±0.08 MPa). To confirm that the improved  50 of dgt was functionally significant, we exposed WT plants to a more intense water deficit (equivalent to dgt’s Ψ 50 ) and, indeed, WT plants did not show photosynthetic recovery under this condition. Therefore, we demonstrate that the changes in the xylem as a function of the mutation in auxin perception result in a severe reduction on in hydraulic efficiency and increased hydraulic safety. Keywords: Ailsa Craig. Gas exchange. Solanum lycopersicum. Water deficit. Water transport. Xylem anatomy.
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    Caracterização morfofisiológica e metabólica de raízes de soja expostas ao alumínio
    (Universidade Federal de Viçosa, 2022-02-23) Andrade, Renata; Ribeiro, Cleberson; http://lattes.cnpq.br/0990000801158034
    Solos ácidos com elevada saturação de alumínio (Al) ocorrem, principalmente em regiões tropicais e subtropicais, podendo comprometer a produtividade de plantas cultivadas. Sob essas condições, o alongamento da raiz pode ser prejudicado e, portanto, perturbar a absorção de água e nutrientes. No presente estudo, investigamos os sítios de acúmulo do Al nas raízes e seus efeitos sobre o crescimento, a fisiologia, o metabolismo em raízes de soja (Glycine max L.) nos genótipos A7002 e Suprema. As plântulas de soja foram cultivadas em sala de crescimento com solução de Clark contendo 0 (controle) e 100 µM de AlCl 3 , sob pH 4,0 e aeração constante, por 72 horas. Avaliamos os danos causados no alongamento da raiz, na morfologia e anatomia radicular e o teor relativo de Al no ápice da raiz. Também abordamos as respostas antioxidantes da soja ao estresse por Al, bem como moléculas indicadoras de estresses, como ROS e MDA. Os ajustes metabólicos pelas plantas frente ao estresse por Al também foram investigados. Nossos resultados mostraram maior acúmulo de Al nas camadas superficiais do genótipo A7002 e mais internamente no genótipo Suprema. Além disso, o genótipo Suprema acumulou maior teor de Al, fato que prejudicou o crescimento da raiz nesse genótipo. Ambos os genótipos apresentaram resultado positivo para o corante Chrome Azurol’S e pela microanálise de raios-X acoplada ao microscópio eletrônico de varredura (MEV-EDS), sendo possível observar acúmulo de Al nas células do ápice celular. Adicionalmente, pela micrografia obtida pela técnica de microscopia eletrônica de varredura (MEV) observa-se uma descamação nas células das células externas do ápice radicular após exposição ao Al. Ambos os genótipos apresentaram aumento na concentração de açúcares solúveis como glicose e frutose, e para o teor de amido houve redução na Suprema. Já em A7002 ocorreu aumento na concentração de malato nas raízes. Entretanto para as enzimas do estresse oxidativo não ocorreu diferenças significativas quanto suas atividades em ambos os genótipos. Desta forma, o genótipo A7002 demostrou maior tolerância em frente ao Al principalmente pela utilização de dois importantes mecanismos: exsudação de malato e restrição à entrada radial do Al nas raízes imposta pelas células externas das raízes. Por outro lado, o genótipo Suprema se mostrou suscetível ao estresse por Al, acumulando altas concentrações desse metal nas raízes, promovendo danos ao crescimento radicular e modificando o metabolismo primário, além de aumentar a concentração de espécie reativa de oxigênio. Palavras-chave: Toxicidade do alumínio. Ápice radicular. Glycine max. Metabolismo primário. Enzimas antioxidantes.
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    Nickel and glyphosate on the potentiation of the soybean resistance against infection by Phakopsora pachyrhizi
    (Universidade Federal de Viçosa, 2020-03-18) Einhardt, Andersom Milech; Rodrigues, Fabrício de Ávila; http://lattes.cnpq.br/8666942935119852
    In this study, the effects of nickel (Ni) (60 g ha -1 Ni) and glyphosate (Gl) (960 g ha -1 e.a. Gl) spray on the antioxidative, defense, and ethylene metabolisms of soybean plants inoculated with P. pachyrhizi were evaluated. In the first experiment, the severity of Asian soybean rust (ASR) decreased by 35% in plants of cv. TMG 135 treated with Ni (+Ni). The malondialdehyde (MDA) concentration was higher in plants not treated with Ni (-Ni) than in +Ni plants and was linked to ASR severity and extensive colonization of the palisade and spongy parenchyma cells by fungal hyphae. The lignin concentration, β-1,3-glucanase (GLU) activity, and expression of the URE gene and the defense-related genes PAL1.1, PAL2.1, CHI1B1, and PR-1A were up- regulated in +Ni infected plants. Taken together, the information provided in this study showed the great potential of Ni to increase the basal level of soybean resistance to ASR and to complement other control methods within the context of sustainable agriculture. In the second experiment, ASR severity in plants of cv. TMG 135 decreased by 34% due to Ni supply. In inoculated plants, the MDA concentration and superoxide (O2-) and hydrogen peroxide (H2O2) accumulation were lower for +Ni plants in comparison to -Ni plants. The antioxidant enzymes activities were inefficient to avoid the high reactive species of oxygen (ROS) accumulation on -Ni inoculated plants. The photosynthetic pigments, maximum photochemical efficiency of photosystem II (PSII), effective yield of PSII, electron transport rate, rate of net carbon assimilation, stomatal conductance to water vapor, and transpiration rate values were higher and the yield for other non-regulated losses and internal CO2 concentration values were lower for +Ni inoculated plants in comparison to -Ni inoculated plants. High ROS production and the great damage to the photosynthetic apparatus damage caused by P. pachyrhizi infection on -Ni plants affected the synthesis of the sugars and increased the energetic consumption limiting therefore, the plant energetic reserves faster in contrast to +Ni plants. In conclusion, the cellular oxidative damage and the impairment on the photosynthetic apparatus of soybean plants caused by P. pachyrhizi infection were alleviated by supplying Ni foliarly. In the thirst experiment, ASR severity was lower by 37, 68, and 77% in plants of cv. TMG 132 supplied with Ni, Gl, and Ni and Gl (Ni+Gl) in comparison to plants supplied with water (control). The inoculation caused largest and fastest increase in the concentration of ROS and MDA in control plants in comparison to Ni and Gl plants. In inoculated plants, the Ni and Gl increased phenylalanine ammonia lyase and GLU activities and phenolics concentration. Additionally, Ni-treated plants showed a fasted cell wall lignification than control plants. Polyphenoloxidase activity was increased by Gl at 5 days after inoculation, regardless of P. pachyrhizi infection. In conclusion, this study demonstrated that Ni and Gl regulate differently the activity of defense enzymes and did not affect the antioxidant enzymes in soybean plants infected by P. pachyrhizi. In the fourth experiment, the ASR severity was reduced on plants of cv. TMG 132 sprayed with Ni and Gl. Carotenoids and chlorophylls concentrations were preserved for Ni, Gl, and Ni+Gl inoculated plants in comparison to that in control plants. Parameters of chlorophyll a fluorescence revealed photosynthetic apparatus damage and lowest destination of energy to photochemistry process on inoculated plants from the control treatment. Limitations on the photosynthetic machinery capacity of inoculated plants to capture light and use the absorbed energy by PSII reflected on their capacity to reduce the CO2 as indicated by the high values for internal CO2 concentration and low values for rate of net carbon assimilation. Low sugars concentration on inoculated plants from the control treatment was linked to their reduced photosynthetic capacity due to the high ASR severity. For non-inoculated plants, ethylene concentration was not affected by Ni and Gl, but its concentration decreased for inoculated plants being more pronounced for plants from the control treatment. In conclusion, this study sheds light into the role played by both Ni and Gl on ASR control from a physiological point of view. Soybean plants exposed to Ni and Gl were able to maintain their photosynthetic capacity and the great ethylene concentration during the infection process of P. pachyrhizi. Keywords: Plant nutrition. Herbicide. Host defense. Photosynthesis. Asian Soybean Rust.
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    The antagonistic effect of AtCCR4a upon drought or heat stress conditions
    (Universidade Federal de Viçosa, 2021-08-27) Ponte, Lucas Roani; Reis, Pedro Augusto Braga dos; http://lattes.cnpq.br/9529336344331566
    Climate changes are expected to increase the severity of environmental adversities to plants, such as changes in rainfall regimes and the occurrence of more extreme temperatures, imposing a major risk to the productivity of agricultural crops. Throughout evolution, plants have evolved elegant mechanisms to cope with different adverse conditions, through the activation of different signaling pathways. The occurrence of abiotic stresses, such as osmotic stress or endoplasmic reticulum stress, tend to activate specific cellular pathways, such as the death cell signaling pathway mediated by proteins that contain DCD/NRP domains. The AtNRP1 and AtNRP2 proteins, components of the pathway in Arabidopsis, have been characterized as effectors of the programmed cell death process by the breakdown of the vacuolar membrane. Understanding how this pathway is integrated into cellular stability is essential, which justifies checking the predicted and not yet functionally characterized interactions among the components of the pathway with other proteins, such as AtCCR4a, a deadenylase that is both active in mRNA processing and in sucrose/starch metabolism. Given this context, we aimed to investigate the interaction between AtNRP2 and AtCCR4a, and its role during heat and drought stresses. We did not observe its direct involvement in the NRP-signaling pathway, however AtCCR4a was induced by osmotic and heat stresses. Furthermore, AtCCR4a disruption provides a drastically heat stress-sensitive phenotype, leading to reductions in photosynthetic pigment contents days after exposure to stress and negative changes in carbohydrate metabolism during this condition. Surprisingly, AtCCR4a disruption also promotes a more tolerant phenotype to water deficit, contributing to greater maintenance of relative water contents in leaf tissues and plant survival rate. These results indicate that AtCCR4a may have an antagonistic function in stress-responsive pathways, probably by regulating at a post-transcriptional level the expression of certain genes and/or by selecting specific target mRNAs. Keywords: Abiotic. Arabidopsis. Deadenylase. Heat. Water.
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    Alumínio altera a morfofisiologia e o metabolismo em folhas e raízes de soja
    (Universidade Federal de Viçosa, 2021-07-28) Castro, Jailson Sousa de; Ribeiro, Cleberson; http://lattes.cnpq.br/6214942343634005
    Solos ácidos apresentam alta saturação de alumínio (Al) apresentando efeitos tóxicos para as plantas, interagindo com diferentes biomoléculas e vias metabólicas e resultando em danos anatômicos e/ou morfofisiológicos, prejudicando a produção agrícola. No presente estudo, investigamos respostas morfoanatômicas e fisiológicas em plantas de soja (Glycine max L.) cv. EMBRAPA 48 e MONSOY 8644 cultivados em solução hidropônica sob condições controladas com três concentrações de Al (0, 100 e 300 µM de Al 3 Cl 3 ) por 3 e 6 dias. Após o cultivo ambos cultivares apresentaram similar absorção de Al entre dias. Plantas MONSOY 8644 obtiveram maior acúmulo de Al em folhas e raízes de acordo com o aumento da disponibilidade, aumento na taxa de crescimento relativo de parte aérea, maior conteúdo de clorofilas, acúmulo de metabolitos primários e compostos fenólicos totais, maior atividade enzimática de APX e POX em folhas e CAT em raízes, e menores danos na morfologia de raízes, plantas EMBRAPA 48 mostraram maiores resultados em proteínas em altas doses de Al, aumento no conteúdo de amido em folhas, associado com a diminuição na área foliar, e menores conteúdos de H2O2 em folhas, ocorrendo localização de Al nas camadas superficiais dos ápices de raízes resultando em desorganização celular nas células da epiderme. Concluindo que o Al apresenta poucos danos ao crescimento dos cultivares de soja, propiciando estabilidade fotossintética o que permite a síntese e acúmulo de corpos carbônicos, tendo o cultivar MONSOY 8644 mecanismos mais apurados de resistência ao Al. Palavras-chave: Glycine max. Tolerância. Estresse Abiótico.
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    Cloning and functional characterization of the OBSCURAVENOSA gene in tomato (Solanum lycopersicum L.)
    (Universidade Federal de Viçosa, 2020-12-22) Moreira, Juliene dos Reis; Zsögön, Agustin; http://lattes.cnpq.br/7790254421084872
    Heterobaric and homobaric leaves are found in many plant families and have a remarkable distribution in nature. What differentiates these two types of leaves is the presence or absence of bundle sheath extensions (BSEs), a structural trait which produces different physiological responses. Leaves with BSEs (heterobaric) have greater hydraulic integration and greater photosynthetic performance, on the other hand, leaves without BSEs (homobaric) have uniform photosynthesis along the blade and probably an improved mechanism to control water loss under stress conditions. Tomatoes currently cultivated were selected after long years of crop breeding. Originally, tomato is a heterobaric crop, however, most field cultivars have a spontaneous recessive mutation known as obscuravenosa (obv) and, as a consequence, have lost the BSEs. For several years, this mutation was unconsciously selected in conjunction with other traits of agronomic interest. This suggests that the variation between homobaric and heterobaric characters has agronomic value in tomato. The first step to better understand the impacts of BSE at the plant level and to be able to manipulate it within the tomato crop and in other crops is knowing the genes involved in its formation. For this, we use tomato as a model to elucidate the molecular bases that control the development of BSEs. Using publicly available resources combined with in silico analysis, we identified a strong candidate gene for the obv mutation. Solyc05g054030 has a SNP (A→G) in the third exon, which leads to the exchange of a histidine residue for arginine at position 135 of the protein. The gene encodes a zinc finger transcription factor C2H2 type. We have shown through predictions that the OBV protein has three classic zinc finger domains, which allow interaction with DNA. In the obv mutant, the exchange of histidine for arginine caused the loss of a zinc finger motif, which may have led to the interruption of the protein functionality. We complemented the obv mutant with the functional OBV allele recovering the clear vein phenotype . OBV further regulates the leaf insertion angle, leaf serration, vein density and fruit shape. OBV appears to coordinate the development of BSEs through an auxin-mediated mechanism, specifically by changes in some members involved in auxin signaling (ARFs and Aux/IAAs). We have identified a link between OBV and AUXIN RESPONSE FACTOR 4 (ARF4). The findings reported here will give support for identification of other components linked to the molecular pathway that directs the formation of BSEs in leaves. Keywords: Bundle Sheath Extension. Heterobaric leaf. Molecular cloning. Auxin.
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    ZAR1: um modulador negativo da resposta aos estresses por deficiência hídrica e do retículo endoplasmático
    (Universidade Federal de Viçosa, 2020-02-17) Fagundes, Débora Pellanda; Reis, Pedro Augusto Braga dos; http://lattes.cnpq.br/0872098826327622
    Estresses bióticos e abióticos são os principais desafios na agricultura e estudos de vias de sinalização são importantes para contornar essa problemática. A via de sinalização de morte celular programada (PCD) media por NRP/DCDs se destaca pela integração da resposta molecular de diversos estresses bióticos e abióticos culminando na morte celular programada. Esta via é modulada negativamente pela chaperona molecular BiP por mecanismos ainda não elucidados. A superexpressão da chaperona molecular BiP permite uma maior tolerância a condições de estresses osmótico e do retículo endoplasmático (RE) sob condições de deficiência hídrica. Em busca de genes envolvidos no mecanismo de tolerância mediado por BiP e seu efeito na via PCD mediada por NRP/DCDs, um escrutínio genético em plantas superexpressando BiP mutagenisadas foi realizado. Foram selecionadas plantas mutantes que suprimiam o fenótipo de tolerância a seca mediado pelo chaperone molecular BiP. Estas linhagens tiveram o genoma sequenciado e a identificação de mutações especificas permitiu a identificação de alguns genes candidatos. Assim ZAR1 (Zygotic Arrest 1), gene que codifica um receptor do tipo cinase (RLK) foi selecionado como gene candidato a supressor do mecanismo mediado por BiP. O presente trabalho realizou experimentos para tentar caracterizar o papel molecular e fisiológico de ZAR1. Foram geradas plantas superexpressando ZAR1 e plantas que tinham o gene de zar1 silenciado. Nos experimentos realizados foi demonstrado que o nível de expressão de ZAR1 altera o fenótipo de plantas de Arabidopsis thaliana, em condições de estresse no RE e estresse por deficiência hídrica. Sob deficiência hídrica plantas silenciadas para o gene zar1 apresentaram um fenótipo mais sensível a deficiência hídrica, comparado com plantas Col0, enquanto plantas superexpressando ZAR1 apresentaram um fenótipo mais tolerante que a Col0. Além disso, plantas superexpressando ZAR1 possuem um atraso do processo de morte celular induzida por um agente causador de estresse no RE (tunicamicina), enquanto plantas silenciadas apresentaram o processo de morte celular acelerado comparado com plantas controle. Através de ensaios de fosforilação in vivo foi demonstrado que ZAR1 é fosforilada em resíduos de serina e tirosina em condições de estresse no RE ou estresse osmótico. No entanto, não foi possível identificar quais os resíduos específicos de aminoácidos são os alvos de modificações pós-traducionais nestas condições. Embora se saiba que há interação entre ZAR1 e RGS1 (Regulador da Sinalização de Proteína G), a fosforilação de ZAR1 sobre RGS1 não havia sido identificada. Assim, um ensaio de fosforilação in vitro também foi realizado e demonstrou que ZAR1 pode fosforilar RGS1 em resíduos de serina ainda não caracterizados. Coletivamente, os resultados indicam que ZAR1 pode estar envolvido com a via de tolerância ao estresse por déficit hídrico e no RE ao atenuar da morte celular ativada por estresses. Além disso, ZAR1 pode atuar como um modulador da via de proteínas G heterotriméricas através da interação/modulação de RGS1, apresentando um papel-chave na resposta de estresse abiótico. Palavras-chave: RLK. Resposta a Estresse. Sinalização Celular.