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Differential Responses to Chilling in Stylosanthes guianensis (Aublet) Sw. and Its Mutants
Author(s) -
Lu Shaoyun,
Wang Xianghui,
Guo Zhenfei
Publication year - 2013
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2012.0333
Subject(s) - photosynthesis , chemistry , photosystem ii , catalase , superoxide dismutase , ascorbic acid , mutant , antioxidant , botany , horticulture , biology , biochemistry , food science , gene
Stylosanthes guianensis (Aublet) Sw., an important forage legume in tropical and subtropical regions, is sensitive to chilling stress. To understand its physiological mechanism of chilling resistance, physiological responses to chilling in antioxidants and photosynthesis in three γ‐ray‐irradiated chilling‐resistant mutants and the parent cultivar CIAT184 were analyzed and compared. Activities of superoxide dismutase, catalase, and ascorbate peroxidase and contents of ascorbic acid and glutathione increased in all plants within 4 d after chilling treatment at 6°C, followed by a gradual decrease. Chilling decreased the net photosynthetic rate, the maximum photochemical efficiency, quantum efficiency of photosystem II (PSII) photochemistry, photochemical quenching efficient, and excitation energy allocated to PSII photochemistry, while higher levels were maintained in the mutants than in CIAT184. Thermal energy dissipation increased during chilling and showed no difference between the mutants and CIAT184. Chilling resulted in an increase in the excess of energy excitation ( E x ), but the mutants had lower levels of E x than CIAT184. The results suggest that the higher levels of the antioxidant defense system induced by low temperature in the mutants may improve protection of photosynthesis against chilling‐induced oxidative damage and increase chilling resistance.