Respostas bioquímicas e fisiológicas de mutantes fotomorfogenéticos de tomateiro (Solanum lycopersicum L. cv. Micro-Tom) sob deficiência hídrica

• Autor(a) principal: Alves, Frederico Rocha Rodrigues
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/4542
• topic: Aurea; High-pigment 1; Fluorescência da clorofila; Enzimas antioxidantes; Aurea; High-pigment 1; Chlorophyll fluorescence; Antioxidant enzymes; CIENCIAS BIOLOGICAS::BOTANICA

Phytochrome-dependent physiological processes are being unveiled by photomorphogenic mutant plants. In tomato (Solanum lycopersicum L.), the aurea mutant is phytochrome-deficient and the high-pigment 1 mutant (hp1) has exaggerated light responses. Phytochromes are related to many abiotic and biotic stress responses due to its role in the regulation of specific genes transcription, acting upon biochemical and molecular mechanisms of cell signaling. Here, we examined the effects of water-withholding over water potential, leaf gas exchanges, chlorophyll fluorescence parameters and chloroplast pigments content in photomorphogenic tomato mutants aurea and hp1, as well its wild-type cultivar Micro-Tom (MT). The plants were grown in a greenhouse under controlled conditions of temperature (24-27ºC) and humidity (60-70%). Analysis were made in 35-days-old plants (n=5) which irrigation was suspended for 5 days and then rehydrated in the sixth day. As control, five plants of each genotype remained well-watered. Water-withholding decreased the water potential and affected leaf gas exchange rates in all studied genotypes, decreasing rates of photosynthesis and stomatal conductance from the fourth treatment day on. Initial fluorescence and PSII potential quantum efficiency were not affected by the water-withholding treatment in general, but MT showed significant decrease in PSII operating efficiency and electron transporte rate as well as an increase in non-photochemical quenching parameters, facts not registered for the mutants during the treatment period. hp1 mutant has the highest content of chlorophyll a, chlorophyll b and carotenoids, this last playing a central role in the oxidative stress defense. Under water-withholding conditions, MT presented the highest MDA concentration and aurea displayed high activities of catalase, peroxidase and ascorbate peroxidase when compared to the other genotypes. The present data allows the conclusion that the mutants have higher tolerance to drought stress than the wild Micro-Tom genotype.