The antioxidative defense system is involved in the delayed senescence in a wheat mutant tasg1

Wheat, which is the most important food crop worldwide, is a cereal that presents considerable potential for increased yield. A new wheat (Triticum aestivum L.) mutant tasg1 with delayed leaf senescence was constructed using ethyl methane sulfonate as a mutagen. Natural senescence in tasg1 was distinctly delayed in the field, as indicated by the slower progression of chlorophyll degradation, net photosynthetic rate than its wild type. Further, the malondialdehyde and the hydrogen peroxide content was lower and antioxidative enzyme activity higher in tasg1 than those in its wild type during both natural senescence and methyl viologen-induced oxidative stress. The results suggest that tasg1 is a functional stay-green wheat mutant with the Type B (in which senescence initiates on schedule, but progresses at a rate lower than that in the respective WTs) or Type A (in which senescence initiates late but proceeds at a normal rate) and B combination and that the competence of the antioxidant defense system is one of the most important mechanisms underlying the expression of the stay-green phenotype.