BZR1 coordinates multiple pathways to promote axillary bud outgrowth in model M. truncatula and forage yield in alfalfa

IF 5.7 2区生物学 Q1 PLANT SCIENCES

Plant Physiology and Biochemistry Pub Date : 2025-09-15 DOI:10.1016/j.plaphy.2025.110531

Yin Yanling, Liu Siyu, Wang Yumiao, Wu Jiarui, Xu Xiao, Fan Shugao

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引用次数: 0

Abstract

Brassinosteroids (BRs) regulate plant architecture through the transcription factor BZR1, yet the molecular mechanisms underlying its role in axillary bud (AB) outgrowth and branching remain poorly characterized in M. truncatula. Here, we investigated the function of MtBZR1 using a null mutant (mtbzr1) through integrated phenotypic, transcriptomic, and hormonal analyses. Phenotypic comparisons revealed that the mtbzr1 mutant exhibited a 22.9 % reduction in primary branches, shorter ABs, and significantly lower biomass accumulation than the wild type (WT). Treatment with 24-epibrassinolide (EBR) promoted AB elongation in isolated stem segments of WT, whereas this response was severely attenuated in mtbzr1, confirming the essential role of MtBZR1 in BR-mediated AB outgrowth. Transcriptomic profiling identified 27,624 differentially expressed genes (DEGs) in the ABs of mtbzr1 compared to WT, with pronounced suppression of photosynthesis-related genes and cell cycle regulators. Hormone pathway analysis revealed transcriptional repression of auxin biosynthesis genes, coupled with elevated expression of strigolactone (SL) and abscisic acid (ABA) biosynthetic/signaling components. Quantification of endogenous hormones confirmed reduced indole-3-acetic acid (IAA) and elevated ABA levels in the ABs of mtbzr1. Overexpression of the homologous gene MsBZR1 (74.0 % protein identity to MtBZR1) in alfalfa (Medicago sativa L.) resulted in a 43.1–59.8 % increase in branching, consequently improving biomass, highlighting its yield promotion potential in forage crop. Collectively, these findings delineate the MtBZR1-mediated regulatory network controlling AB development in M. truncatula and provide strategic genetic targets for forage productivity enhancement.

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BZR1协调多种途径促进模型M. truncatula腋芽生长和苜蓿饲料产量。

油菜素内酯（BRs）通过转录因子BZR1调节植物结构，但其在M. truncatula中腋芽（AB）生长和分支中的作用的分子机制尚不清楚。在这里，我们通过综合表型、转录组学和激素分析，利用零突变体（MtBZR1）研究了MtBZR1的功能。表型比较显示，与野生型（WT）相比，mtbzr1突变体的一次分枝减少了22.9%，抗体更短，生物量积累显著降低。24-表油菜素内酯（EBR）处理促进了WT分离茎段的AB伸长，而mtzr1的这种反应严重减弱，证实了mtbzr1在br介导的AB生长中的重要作用。转录组学分析发现，与WT相比，mtzr1的抗体中有27,624个差异表达基因（DEGs），光合作用相关基因和细胞周期调节因子明显受到抑制。激素通路分析显示，生长素生物合成基因的转录抑制，以及独角麦内酯（SL）和脱落酸（ABA）生物合成/信号成分的表达升高。内源激素测定证实，mtzr1抗体中吲哚-3-乙酸（IAA）水平降低，ABA水平升高。在苜蓿（Medicago sativa L.）中过表达同源基因MsBZR1（与MtBZR1蛋白同源率为74.0%），可使分支增加43.1- 59.8%，从而提高生物量，凸显其在饲料作物中的增产潜力。综上所述，这些发现揭示了mtbzr1介导的截断草AB发育调控网络，为提高牧草产量提供了战略性遗传靶点。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Plant Physiology and Biochemistry 生物-植物科学

CiteScore

11.10

自引率

3.10%

发文量

410

审稿时长

33 days

期刊介绍： Plant Physiology and Biochemistry publishes original theoretical, experimental and technical contributions in the various fields of plant physiology (biochemistry, physiology, structure, genetics, plant-microbe interactions, etc.) at diverse levels of integration (molecular, subcellular, cellular, organ, whole plant, environmental). Opinions expressed in the journal are the sole responsibility of the authors and publication does not imply the editors'' agreement. Manuscripts describing molecular-genetic and/or gene expression data that are not integrated with biochemical analysis and/or actual measurements of plant physiological processes are not suitable for PPB. Also "Omics" studies (transcriptomics, proteomics, metabolomics, etc.) reporting descriptive analysis without an element of functional validation assays, will not be considered. Similarly, applied agronomic or phytochemical studies that generate no new, fundamental insights in plant physiological and/or biochemical processes are not suitable for publication in PPB. Plant Physiology and Biochemistry publishes several types of articles: Reviews, Papers and Short Papers. Articles for Reviews are either invited by the editor or proposed by the authors for the editor''s prior agreement. Reviews should not exceed 40 typewritten pages and Short Papers no more than approximately 8 typewritten pages. The fundamental character of Plant Physiology and Biochemistry remains that of a journal for original results.