AUTHOR=Shan Binghui , Wang Wei , Cao Jinfeng , Xia Siqi , Li Ruihua , Bian Shaomin , Li Xuyan 

TITLE=Soybean GmMYB133 Inhibits Hypocotyl Elongation and Confers Salt Tolerance in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.764074

DOI=10.3389/fpls.2021.764074

ISSN=1664-462X

ABSTRACT=<p><italic>REVEILLE</italic> (<italic>RVE</italic>) genes generally act as core circadian oscillators to regulate multiple developmental events and stress responses in plants. It is of importance to document their roles in crops for utilizing them to improve agronomic traits. Soybean is one of the most important crops worldwide. However, the knowledge regarding the functional roles of <italic>RVE</italic>s is extremely limited in soybean. In this study, the soybean gene <italic>GmMYB133</italic> was shown to be homologous to the <italic>RVE8</italic> clade genes of <italic>Arabidopsis</italic>. <italic>GmMYB133</italic> displayed a non-rhythmical but salt-inducible expression pattern. Like <italic>AtRVE8</italic>, overexpression of <italic>GmMYB133</italic> in <italic>Arabidopsis</italic> led to developmental defects such as short hypocotyl and late flowering. Seven light-responsive or auxin-associated genes including <italic>AtPIF4</italic> were transcriptionally depressed by <italic>GmMYB133</italic>, suggesting that <italic>GmMYB133</italic> might negatively regulate plant growth. Noticeably, the overexpression of <italic>GmMYB133</italic> in <italic>Arabidopsis</italic> promoted seed germination and plant growth under salt stress, and the contents of chlorophylls and malondialdehyde (MDA) were also enhanced and decreased, respectively. Consistently, the expressions of four positive regulators responsive to salt tolerance were remarkably elevated by <italic>GmMYB133</italic> overexpression, indicating that <italic>GmMYB133</italic> might confer salt stress tolerance. Further observation showed that <italic>GmMYB133</italic> overexpression perturbed the clock rhythm of <italic>AtPRR5</italic>, and yeast one-hybrid assay indicated that GmMYB133 could bind to the <italic>AtPRR5</italic> promoter. Moreover, the retrieved ChIP-Seq data showed that AtPRR5 could directly target five clients including <italic>AtPIF4</italic>. Thus, a regulatory module <italic>GmMYB133-PRR5-PIF4</italic> was proposed to regulate plant growth and salt stress tolerance. These findings laid a foundation to further address the functional roles of <italic>GmMYB133</italic> and its regulatory mechanisms in soybean.</p>