Cao Liru, Lu Xiaomin, Wang Guorui, Zhang Qianjin, Zhang Xin, Fan Zaifeng, Cao Yanyong, Wei Li, Wang Tongchao, Wang Zhenhua
Grain Crops Research Institute, Henan Academy of Agricultural Sciences, Zhengzhou, China.
National Key Laboratory of Wheat and Maize Crop Science, College of Agronomy, Henan Agricultural University, Zhengzhou, China.
Front Plant Sci. 2021 Apr 1;12:629903. doi: 10.3389/fpls.2021.629903. eCollection 2021.
Analyzing the transcriptome of maize leaves under drought stress and rewatering conditions revealed that transcription factors were involved in this process, among which of the ABSCISIC ACID-INSENSITIVE 5-like protein 5 family was induced to significantly up-regulated. The functional mechanism of in Abscisic acd (ABA) signaling pathway and its response to drought stress and rewatering has not been studied yet. The present study found that ZmbZIP33 contains a DNA-binding and dimerization domain, has transcriptional activation activity, and is highly homologous to SbABI1,SitbZIP68 and OsABA1. The expression of is strongly up-regulated by drought, high salt, high temperature, and ABA treatments. Overexpression of remarkably increased chlorophyll content and root length after drought stress and rewatering, and, moreover, cause an accumulation of ABA content, thereby improving drought resistance and recovery ability in . However, silencing the expression of (BMV-ZmbZIP33) remarkably decreased chlorophyll content, ABA content, superoxide dismutase and peroxidase activities, and increased stomatal opening and water loss rate compared with BMV (control). It showed that silencing lead to reduced drought resistance and recovery ability of maize. ABA sensitivity analysis found that 0.5 and 1 μmol/L treatments severely inhibited the root development of overexpression transgenic . However, the root growth of BMV was greatly inhibited for 1 and 5μmol/L ABA treatments, but not for BMV-ZmbZIP33. Subcellular localization, yeast two-hybrid and BIFC further confirmed that the core components of ABA signaling pathways ZmPYL10 and ZmPP2C7 interacted in nucleus, ZmPP2C7 and ZmSRK2E as well as ZmSRK2E and ZmbZIP33 interacted in the plasma membrane. We also found that expression levels of and in the BMV-ZmbZIP33 mutant were lower than those of BMV, while was the opposite under drought stress and rewatering. However, expression of and in normal maize leaves were significantly up-regulated by 3-4 folds after drought and ABA treatments for 24 h, while was down-regulated. The and encoding key enzymes in ABA biosynthesis are up-regulated in overexpression transgenic line under drought stress and rewatering conditions, but down-regulated in BMV-ZmbZIP33 mutants. Together, these findings demonstrate that played roles in ABA biosynthesis and regulation of drought response and rewatering in and maize thought an ABA-dependent signaling pathway.
分析干旱胁迫和复水条件下玉米叶片的转录组发现，转录因子参与了这一过程，其中ABSCISIC ACID-INSENSITIVE 5-like protein 5家族被诱导显著上调。其在脱落酸（ABA）信号通路中的功能机制及其对干旱胁迫和复水的响应尚未得到研究。本研究发现，ZmbZIP33含有一个DNA结合和二聚化结构域，具有转录激活活性，并且与SbABI1、SitbZIP68和OsABA1高度同源。其表达受干旱、高盐、高温和ABA处理强烈上调。过表达ZmbZIP33在干旱胁迫和复水后显著增加了叶绿素含量和根长，此外，还导致ABA含量积累，从而提高了玉米的抗旱性和恢复能力。然而，与BMV（对照）相比，沉默ZmbZIP33的表达（BMV-ZmbZIP33）显著降低了叶绿素含量、ABA含量、超氧化物歧化酶和过氧化物酶活性，并增加了气孔开度和失水率。这表明沉默ZmbZIP33导致玉米抗旱性和恢复能力降低。ABA敏感性分析发现，0.5和1μmol/L处理严重抑制了过表达ZmbZIP33转基因植株的根系发育。然而，1和5μmol/L ABA处理对BMV的根系生长有很大抑制作用，但对BMV-ZmbZIP33没有。亚细胞定位、酵母双杂交和BIFC进一步证实，ABA信号通路的核心组分ZmPYL10和ZmPP2C7在细胞核中相互作用，ZmPP2C7和ZmSRK2E以及ZmSRK2E和ZmbZIP33在质膜中相互作用。我们还发现，在干旱胁迫和复水条件下，BMV-ZmbZIP33突变体中ZmbZIP33和ZmPYL10的表达水平低于BMV，而ZmPP2C7则相反。然而，在干旱和ABA处理24小时后，正常玉米叶片中ZmPP2C7和ZmPYL10的表达显著上调3-4倍，而ZmbZIP33则下调。在干旱胁迫和复水条件下，过表达ZmbZIP33转基因株系中ABA生物合成关键酶的编码基因上调，但在BMV-ZmbZIP33突变体中下调。总之，这些发现表明，ZmbZIP33通过ABA依赖的信号通路在玉米ABA生物合成以及干旱响应和复水调控中发挥作用。
