AUTHOR=Cao Liru , Lu Xiaomin , Wang Guorui , Zhang Qianjin , Zhang Xin , Fan Zaifeng , Cao Yanyong , Wei Li , Wang Tongchao , Wang Zhenhua 

TITLE=Maize ZmbZIP33 Is Involved in Drought Resistance and Recovery Ability Through an Abscisic Acid-Dependent Signaling Pathway

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.629903

DOI=10.3389/fpls.2021.629903

ISSN=1664-462X

ABSTRACT=<p>Analyzing the transcriptome of maize leaves under drought stress and rewatering conditions revealed that transcription factors were involved in this process, among which <italic>ZmbZIP33</italic> of the ABSCISIC ACID-INSENSITIVE 5-like protein 5 family was induced to significantly up-regulated. The functional mechanism of <italic>ZmbZIP33</italic> 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 <italic>ZmbZIP33</italic> is strongly up-regulated by drought, high salt, high temperature, and ABA treatments. Overexpression of <italic>ZmbZIP33</italic> 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 <italic>Arabidopsis</italic>. However, silencing the expression of <italic>ZmbZIP33</italic> (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 <italic>ZmbZIP33</italic> 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 <italic>ZmbZIP33</italic> transgenic <italic>Arabidopsis</italic>. 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 <italic>ZmPYL10</italic> and <italic>ZmSRK2E</italic> in the BMV-ZmbZIP33 mutant were lower than those of BMV, while <italic>ZmPP2C7</italic> was the opposite under drought stress and rewatering. However, expression of <italic>ZmPYL10</italic> and <italic>ZmSRK2E</italic> in normal maize leaves were significantly up-regulated by 3–4 folds after drought and ABA treatments for 24 h, while <italic>ZmPP2C7</italic> was down-regulated. The <italic>NCED</italic> and <italic>ZEP</italic> encoding key enzymes in ABA biosynthesis are up-regulated in overexpression <italic>ZmbZIP33</italic> transgenic line under drought stress and rewatering conditions, but down-regulated in BMV-ZmbZIP33 mutants. Together, these findings demonstrate that <italic>ZmbZIP33</italic> played roles in ABA biosynthesis and regulation of drought response and rewatering in <italic>Arabidopsis</italic> and maize thought an ABA-dependent signaling pathway.</p>