Overexpression of GmUBC9 Gene Enhances Plant Drought Resistance and Affects Flowering Time via Histone H2B Monoubiquitination

Abstract

Ubiquitylation is a form of post-translational modification of proteins that can alter localization, functionality, degradation, or transcriptional activity within a cell. E2 ubiquitin-conjugating enzyme (UBC) and E3 ubiquitin ligases are the primary determinants of substrate specificity in the context of ubiquitin conjugation. Multiubiquitination modifies target proteins for 26S proteasome degradation, while monoubiquitination controls protein activation and localization. At present, research on the monoubiquitination, especially histone monoubiquitination, has mostly focused on model plants with relatively few on crop species. In this study, we identified 91 UBC-like genes in soybean. The chromosomal localization, phylogenetic relationships, gene structures, and putative cis-acting elements were evaluated. Furthermore, the tissuespecific expression patterns of UBC Class I genes under drought stress were also investigated. Among Class I genes, GmUBC9 induction in response to drought stress was evident, and so this gene was selected for further analysis. GmUBC9 localized to the nucleus and endoplasmic reticulum. The overexpression of GmUBC9 in Arabidopsis led to enhanced tolerance for drought conditions across a range of stages of development, while overexpression in soybean hairy roots similarly led to improvements in tolerance for drought conditions, increased proline content, and reduced MDA content in soybean seedlings compared to wild type plants. HISTONE MONOUBIQUITINATION 2 (HUB2), an E3-like protein involved in histone H2B ubiquitylation (H2Bub1), was found to interact with GmUBC9 through Y2H analysis and BiFC assays in Arabidopsis and soybean. Under drought conditions, the level of H2Bub1 increased, and transcription of drought response genes was activated in GmUBC9 transgenic Arabidopsis and soybean. In addition, GmUBC9 transgenic Arabidopsis and soybean showed a late-flowering phenotype and

Genome-wide association analysis for drought tolerance and associated traits in faba bean (Vicia faba L.)

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“…UBC gene coding for ubiquitin C is a stress related gene, which correlates positively with higher drought tolerance in Arabidopsis and soybean ( Glycine max (L.) Merr.) by conjugating ubiquitin to remove or unfold damaged proteins ( Chen et al, 2020 ).…”

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“…In contrast to acetylation and methylation, histone ubiquitination and phosphorylation have been only sparsely studied. Monoubiquitination of histone lysine H2Bub is considered an active mark in salt and drought stress response ( Chen et al, 2020 ). However, the mono-ubiquitination of histones is an important HPTM that occurs on histones H2A and H2B at lysine K121 and K143 respectively ( March and Farrona, 2018 ).…”