A stress-responsive bZIP transcription factor OsbZIP62 improves drought and oxidative resistance in rice

Transcription factors play a crucial regulatory role in plant drought stress responses. In this study, a novel drought stress related bZIP transcription factor, OsbZIP62, was identified in rice. This gene was selected from transcriptome analysis of several typical rice varieties with different drought tolerance. The expression of OsbZIP62 was obviously induced by drought, hydrogen peroxide, and abscisic acid (ABA) treatment. Overexpression of OsbZIP62-VP64 (OsbZIP62V) enhanced the drought tolerance and oxidative stress tolerance of transgenic rice, while the osbzip62 mutants showed the opposite phenotype. RNA-seq analysis showed that many stress-related genes (e.g. OsGL1, OsNAC10, and DSM2) were up-regulated in OsbZIP62V plants. OsbZIP62 could bind to the abscisic acid–responsive element (ABRE) and promoters of several putative target genes. Taken together, OsbZIP62 positively regulated rice drought tolerance through regulated the expression of genes associated with stress. To search the downstream genes of OsbZIP62, we performed transcriptome analysis of the OsbZIP62-VP64-overexpressor, osbzip62 mutant and wild-type plants under normal conditions using high-throughput sequencing.

转录因子在植物干旱胁迫响应过程中发挥关键调控作用。本研究在水稻中鉴定得到一个全新的干旱胁迫相关bZIP转录因子OsbZIP62，该基因源自对多个抗旱性存在差异的典型水稻品种的转录组分析。OsbZIP62的表达可被干旱、过氧化氢及脱落酸（abscisic acid, ABA）处理显著诱导。OsbZIP62-VP64（以下简称OsbZIP62V）过表达可提升转基因水稻的抗旱性与氧化胁迫耐受性，而osbzip62基因突变体则呈现相反的表型。RNA测序（RNA-seq）分析结果显示，在OsbZIP62V过表达植株中，多个胁迫相关基因（如OsGL1、OsNAC10及DSM2）的表达量显著上调。OsbZIP62可结合脱落酸应答元件（abscisic acid-responsive element, ABRE）及多个潜在靶基因的启动子区域。综上，OsbZIP62通过调控胁迫相关基因的表达，正向调控水稻的抗旱性。为探究OsbZIP62的下游靶基因，本研究采用高通量测序技术，对正常培养条件下的OsbZIP62-VP64过表达植株、osbzip62基因突变体及野生型植株开展转录组分析。