Proteômica diferencial e caracterização fisiológica de dois clones de Coffea canephora sob déficit hídrico

• Autor(a) principal: Soares, Carla Quinhones Godoy
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4307
• topic: Coffea canephora; Proteômica; Déficit hídrico; Coffea canephora; Proteomics; Water deficit; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::FISIOLOGIA DE PLANTAS CULTIVADAS

Understanding the mechanisms by which plants respond to water stress is crucial to predict the climate change impacts on crop productivity and ecosystems. Plants have long- distance root-to-shoot signaling mechanisms that generate the orchestration of adaptive responses. Root system signaling, as well as shoot, is often considerate important in growth control in response to environmental adverse conditions. This study aimed to integrate the results obtained in robusta coffee through studies of proteins differentially expressed in the root system in clones with differential tolerance (120 tolerant, 109A susceptible) upon water deficit conditions and also evaluate the differential physiological responses upon fast imposed water deficit conditions. The plants were evaluated upon full irrigation (control) and under water deficit imposed by the suspension of irrigation, until the plants reached water potential (Ψam) of -1.5 ± 0.20 MPa (moderate) and -3.0 ± 0.20 MPa (severe). The root differentially expressed proteins were analyzed by two- dimensional gels associated to sequencing by mass spectrometry (MALDI-TOF-TOF). Upon drought, 109A clone showed a reduction in relative abundance in 39 spots, and an increase in 18 spots. 120 clone showed a reduction in relative abundance in 38 spots and an increase in 19 spots. The analysis of root differential proteome in these two clones revealed mechanisms of tolerance and acclimation to water deficit related to carbohydrate metabolism, hormone metabolism, energy metabolism, programmed cell death, abiotic and biotic stresses response, cellular detoxification, oxidative stress, DNA repair and protein processing. The analysis of gas exchange and chlorophyll fluorescence showed that these clones exhibited differential mechanisms in response to water deficit conditions, as already reported. The sensitive clone (109A) showed mechanisms related to drain the excess energy and increase the heat dissipation under moderate water deficit. However, under conditions of severe drought these mechanisms were no more efficient in this clone. On the other hand, tolerant clone (120) under conditions of severe drought showed reduction in effective quantum yield (ΦPSII) associated with a reduction in electron transport rate (ETR) and non-photochemical extinction coefficient (NPQ), followed by an increase in the fraction of absorbed light that was neither used in photochemistry nor dissipated thermally (PE). However this apparent excess of energy was not translated in oxidative damage, suggesting other types of mechanisms involved in the drainage of energy excess, as the modulation of photosystem proteins.