Expression analysis of antioxidant genes in response to drought stress in the fl ag leaf of two Indonesian rice cultivars

The objective of this study was to analysis the expression of antioxidant genes in response to drought stress in Indonesian rice. The malondialdehyde (MDA) content and the expression of Cu-ZnSod1, cCu-ZnSod2, MnSod1, cApxa, cApxb, chl-sApx, Cat1, Cat2, Cat3, Gr1, Gr2, and Gr3 genes were assayed in the rice fl ag leaf of Ciherang and Situ Bagendit cultivars subjected to control, mild and severe drought during the grain fi lling phase. Increase in MDA content of Ciherang treated to mild and severe drought was almost two-fold and three-fold respectively, while MDA content in Situ Bagendit subjected to mild and severe drought increased approximately one-fold and two-fold as compared to the control. The semi quantitative reverse transcription polymerase chain reaction (sqRT-PCR) analysis showed that the expression of cCu-ZnSod1, MnSod1, Cat2, Gr3 genes of Ciherang, and cCu-ZnSod2, MnSod1, cApxa, cApxb, chl-sAPX, Cat2 and Gr1 genes of Situ Bagendit increased in fl ag leaf of plant treated to drought. Expressions of cApxb, chl-sApx, Cat3 of Ciherang and Cu-ZnSod1 and Gr2 genes of Situ Bagendit were not changed signifi cantly by drought stress. Decreased expression was shown by cCu-ZnSod2, cApxa, Cat1, Gr1 and Gr2 genes of Ciherang, and Cat1, Cat3 and Gr3 genes of Situ Bagendit. The results indicated that the activity of oxidative defense was regulated by four genes; cCu-ZnSod1, MnSod1, Cat2, Gr3 in Ciherang, and eight genes; cCu-ZnSod1, cCu-ZnSod2, MnSod1, cApxa, cApxb, chl-sApx, Cat2 and Gr1 in Situ Bagendit. Therefore, differences in the number of antioxidant genes controlling oxidative defense system might determine the difference of the oxidative defense capacity between both cultivars in response to drought stress during grain fi lling