Physiological and biochemical responses of photomorphogenic tomato mutants (cv. Micro-Tom) under water withholding |
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Authors: | Frederico Rocha Rodrigues Alves Hyrandir Cabral de Melo Ailton José Crispim-Filho Alan Carlos Costa Kelly Juliane Telles Nascimento Rogério Falleiros Carvalho |
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Affiliation: | 1.Laboratório de Fisiologia Vegetal,Instituto de Ciências Biológicas, Universidade Federal de Goiás,Goiania,Brazil;2.Laboratório de Ecofisiologia e Produtividade Vegetal,Instituto Federal Goiano,Rio Verde,Brazil;3.Departamento de Biologia Aplicada à Agropecuária,Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista “Júlio de Mesquita Filho”,S?o Paulo,Brazil |
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Abstract: | In addition to mediating photomorphogenesis, phytochromes are responsible for many abiotic stress responses, acting upon biochemical and molecular mechanisms of cell signaling. In this work, we measured the physiological and biochemical responses of phytochrome-mutant plants under water stress. In tomato (Solanum lycopersicum L.), the aurea mutant (au) is phytochrome-deficient and the high-pigment-1 mutant (hp1) has exaggerated light responses. We examined the effects of water withholding on water potential, leaf gas exchange, chlorophyll fluorescence, chloroplast pigment content and antioxidant enzyme activity in au and hp1 and their wild-type cultivar Micro-Tom (MT). Initial fluorescence and potential quantum efficiency of photosystem II (PSII) photochemistry were not affected by the treatment, but effective quantum yield of PSII, electron transport rate decreased and non-photochemical quenching increased significantly in MT. Under water withholding conditions, MT had higher malondialdehyde concentration than the mutants, but au had higher activities of catalase and ascorbate peroxidase compared to the other genotypes. The tolerance of mutants to the effects of water withholding may be explained by the higher activity of antioxidant enzymes in au and by a higher concentration of antioxidant compounds, such as carotenoids, in hp1. |
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