Drought and exogenous abscisic acid alter hydrogen peroxide accumulation and diferentially regulate the expression of two maize RD22-like genes

Abstract

Increased biosynthesis of abscisic acid (ABA) occurs in plants in response to water defcit, which is mediated by changes in the levels of reactive oxygen species such as H2O2. Water defcit and ABA induce expression of some RD22-like proteins. This study aimed to evaluate the efect of water defcit and exogenous ABA (50µM ABA applied every 24hours for a total of 72hours) on H2O2 content in Zea mays (maize) and to characterise genes encoding two putative maize RD22-like proteins (designated ZmRD22A and ZmRD22B). The expression profles of the two putative maize RD22-like genes in response to water defcit and treatment with ABA were examined in leaves. In silico analyses showed that the maize RD22-like proteins share domain organisation with previously characterized RD22-like proteins. Both water defcit and exogenous ABA resulted in increased H2O2 content in leaves but the increase was more pronounced in response to water defcit than to exogenous ABA. Lignin content was not afected by exogenous ABA, whereas it was decreased by water defcit. Expression of both RD22- like genes was up-regulated by drought but the ZmRD22A gene was not infuenced by exogenous ABA, whereas ZmRD22B was highly responsive to exogenous ABA.