Plant hormones (Literature sources on phytohormones and plant signalling)
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Cell cycle-dependent kinase inhibitor GhKRP6, a direct target of GhBES1.4, participates in BR regulation of cell expansion in cotton

Cell cycle-dependent kinase inhibitor GhKRP6, a direct target of GhBES1.4, participates in BR regulation of cell expansion in cotton | Plant hormones (Literature sources on phytohormones and plant signalling) | Scoop.it
Authors: Yu Gu, Jie Zhang, Le Liu, Ghulam Qanmber, Zhao Liu, Kun Xing, Lili Lu, Li Liu, Shuya Ma, Fuguang Li and Zuoren Yang.

The Plant Journal (2023)

Abstract: "The steroidal hormone brassinosteroid (BR) has been shown to positively regulate cell expansion in plants. However, the specific mechanism by which BR controls this process has not been fully understood. In this study, RNA-seq and DAP-seq analysis of GhBES1.4 (a core transcription factor in BR signaling) were used to identify a cotton cell cycle-dependent kinase inhibitor called GhKRP6. The study found that GhKRP6 was significantly induced by the BR hormone, and that GhBES1.4 directly promoted the expression of GhKRP6 by binding to the CACGTG motif in its promoter region. GhKRP6-silenced cotton plants had smaller leaves with more cells and reduced cell size. Furthermore, endoreduplication was inhibited, which affected cell expansion and ultimately decreased fiber length and seed size in GhKRP6-silenced plants compared with the control. The KEGG enrichment results of control and VIGS-GhKRP6 plants revealed differential expression of genes related to cell wall biosynthesis, MAPK, and plant hormone transduction pathways – all of which are related to cell expansion. Additionally, some cyclin-dependent kinase (CDK) genes were up-regulated in the plants with silenced GhKRP6. Our study also found that GhKRP6 could interact directly with a cell cycle-dependent kinase called GhCDKG. Taken together, these results suggest that BR signaling influences cell expansion by directly modulating the expression of cell cycle-dependent kinase inhibitor GhKRP6 via GhBES1.4."
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GhBES1 mediates brassinosteroid regulation of leaf size by activating expression of GhEXO2 in cotton (Gossypium hirsutum)

GhBES1 mediates brassinosteroid regulation of leaf size by activating expression of GhEXO2 in cotton (Gossypium hirsutum) | Plant hormones (Literature sources on phytohormones and plant signalling) | Scoop.it

Authors: Shengdong Li, Kun Xing, Ghulam Qanmber, Guoquan Chen, Le Liu, Mengzhen Guo, Yan Hou, Lili Lu, Lingbo Qu, Zhao Liu and Zuoren Yang.


Plant Molecular Biology (2022)


Key message: We proposed a working model of BR to promote leaf size through cell expansion. In the BR signaling pathway, GhBES1 affects cotton leaf size by binding to and activating the expression of the E-box element in the GhEXO2 promoter region. 


Abstract: "Brassinosteroid (BR) is an essential phytohormone that controls plant growth. However, the mechanisms of BR regulation of leaf size remain to be determined. Here, we found that the BR deficient cotton mutant pagoda1 (pag1) had a smaller leaf size than wild-type CRI24. The expression of EXORDIUM (GhEXO2) gene, was significantly downregulated in pag1. Silencing of BRI1-EMS-SUPPRESSOR 1 (GhBES1), inhibited leaf cell expansion and reduced leaf size. Overexpression of GhBES1.4 promoted leaf cell expansion and enlarged leaf size. Expression analysis showed GhEXO2 expression positively correlated with GhBES1 expression. In plants, altered expression of GhEXO2 promoted leaf cell expansion affecting leaf size. Furthermore, GhBES1.4 specifically binds to the E-box elements in the GhEXO2 promoter, inducing its expression. RNA-seq data revealed many down-regulated genes related to cell expansion in GhEXO2 silenced plants. In summary, we discovered a novel mechanism of BR regulation of leaf size through GhBES1 directly activating the expression of GhEXO2."

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