Soybean GmMYB133 Inhibits Hypocotyl Elongation and Confers Salt Tolerance in Arabidopsis

Abstract

REVEILLE (RVE) 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 RVEs is extremely limited in soybean. In this study, the soybean gene GmMYB133 was shown to be homologous to the RVE8 clade genes of Arabidopsis. GmMYB133 displayed a non-rhythmical but salt-inducible expression pattern. Like AtRVE8, overexpression of GmMYB133 in Arabidopsis led to developmental defects such as short hypocotyl and late flowering. Seven light-responsive or auxin-associated genes including AtPIF4 were transcriptionally depressed by GmMYB133, suggesting that GmMYB133 might negatively regulate plant growth. Noticeably, the overexpression of GmMYB133 in Arabidopsis 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 GmMYB133 overexpression, indicating that GmMYB133 might confer salt stress tolerance. Further observation showed that GmMYB133 overexpression perturbed the clock rhythm of AtPRR5, and yeast one-hybrid assay indicated that GmMYB133 could bind to the AtPRR5 promoter. Moreover, the retrieved ChIP-Seq data showed that AtPRR5 could directly target five clients including AtPIF4. Thus, a regulatory module GmMYB133-PRR5-PIF4 was proposed to regulate plant growth and salt stress tolerance. These findings laid a foundation to further address the functional roles of GmMYB133 and its regulatory mechanisms in soybean.

Genome-wide identification of BBX gene family and their expression patterns under salt stress in soybean

“…Salt stress of ten-day-old soybean seedlings (Williams 82) were performed as previously described [ 75 ]. Briefly, soybean seeds were sterilized and germinated in plate with wet filter paper.…”

Genetic control of stem elongation in legume crops and its potential relevance

“…Given this precedent for an association in other species, it is expected that these hormones perform similar functions in legumes. While direct evidence is limited, heterologous expression of soybean genes in Arabidopsis and tobacco has observed an association between stem elongation and stress tolerance, with some studies also reporting alteration to hormone levels or pathway components (Park et al, 2022;Shan et al, 2021;Y. Zhang et al, 2013;D.…”

“…Given this precedent for an association in other species, it is expected that these hormones perform similar functions in legumes. While direct evidence is limited, heterologous expression of soybean genes in Arabidopsis and tobacco has observed an association between stem elongation and stress tolerance, with some studies also reporting alteration to hormone levels or pathway components (Park et al., 2022; Shan et al., 2021; Y. Zhang et al., 2013; D. Zhang et al., 2017). One example from functional analysis in soybean itself involves overexpression of the MYB gene, GmMYB14 , which enhanced drought tolerance, suppressed internode elongation and root growth, and reduced BR levels through activating the BR catabolic gene GmBEN1 (Chen et al., 2021).…”

A novel miR160a–GmARF16–GmMYC2 module determines soybean salt tolerance and adaptation

“…Other regulatory proteins include the positive salt‐tolerant regulator GmNFYA (Nuclear factor Y subunit), which interacts with the WD‐40 repeat‐containing protein GmFVE (Lu et al ., 2021), and a salt–stress signal amplifier using a feed‐forward loop, consisting of GmSIN1 (Salt Induced 1)–GmNCED3s (9‐ cis ‐epoxycarotenoid dioxygenases)–GmRbohBs (Respiratory burst oxidase homologs) (Li et al ., 2019). Additional transcription factors including GmNAC (NAM/ATAF1/2/CUC2), GmMYB, GmHSFB2b (Heat shock factor B 2b), GmbZIP, and GmWRKY family members, have been shown to play important roles in soybean's response to salt stress (Ma et al ., 2019; Bian et al ., 2020; Yang et al ., 2020; Li et al ., 2021; Shan et al ., 2021). Despite strong progress in exploring these genes, the molecular mechanisms underlying soybean's ability to withstand high salinity levels remain relatively elusive.…”