Strigolactones inhibit axillary bud outgrowth through transcription factor MdSPL6-mediated regulation of ABA levels in apple

IF 6.9 1区生物学 Q1 PLANT SCIENCES

Plant Physiology Pub Date : 2025-10-15 DOI:10.1093/plphys/kiaf517

Xingqiang Fan, Huixia Li, Yao Xiong, Doudou Chen, Yuqing Zhang, Haochen Sun, Yi Wang, Zhenhai Han, Wei Li

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引用次数: 0

Abstract

Lateral branching contributes to plant architecture and agricultural yield. In apple (Malus domestica), the dormancy of axillary buds constrains early branching and fruit production. Among various phytohormones, strigolactones (SLs) play a pivotal role regulating axillary bud outgrowth. This study investigates the inhibitory effects of SLs on apple axillary bud growth and elucidates the underlying molecular mechanisms. Treatment with the SL analog racemic-GR24 (rac-GR24) markedly inhibited the outgrowth of axillary buds. We discovered that the transcription factor in apple SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 6 (MdSPL6) interacts with SUPPRESSOR OF MAX2-LIKE 7 (MdSMXL7), a key component of SL signaling, to regulate branching patterns. The Mdspl6 mutant exhibited enhanced lateral branching, confirming the role of MdSPL6 as a suppressor of bud growth. Through DNA affinity purification sequencing (DAP-seq), we identified apple HOMEOBOX PROTEIN53 (MdHB53) and TEOSINTE BRANCHED1, CYCLOIDEA, PCF18 (MdTCP18) as downstream target genes of MdSPL6. Overexpression of these genes led to elevated levels of abscisic acid (ABA), implicating the function of ABA in the SL-mediated inhibition of bud outgrowth. Our results demonstrate that SLs regulate apple axillary bud growth through MdSPL6 and its downstream targets by modulating ABA levels, offering insights into the genetic control of plant architecture and identifying potential targets for breeding apple varieties with optimized branching and enhanced yield.

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独角孤内酯通过转录因子mdspl6介导的ABA水平调控抑制苹果腋芽生长

横向分枝有助于植物结构和农业产量。在苹果（Malus domestica）中，腋芽的休眠限制了早期分枝和果实的产生。在各种植物激素中，独角甾内酯（SLs）在调节腋芽生长中起着关键作用。本研究探讨了SLs对苹果腋芽生长的抑制作用，并阐明了其潜在的分子机制。SL类似物外消旋- gr24 （rac-GR24）处理明显抑制腋芽的生长。我们发现苹果SQUAMOSA启动子结合蛋白样6 （MdSPL6）的转录因子与MAX2-LIKE 7的抑制因子（MdSMXL7）相互作用，调控分支模式，而MAX2-LIKE 7是SL信号的关键成分。Mdspl6突变体表现出增强的侧分枝，证实了Mdspl6作为芽生长抑制因子的作用。通过DNA亲和纯化测序（DAP-seq），我们鉴定出苹果HOMEOBOX蛋白53 （MdHB53）和TEOSINTE BRANCHED1、CYCLOIDEA、PCF18 （MdTCP18）是MdSPL6的下游靶基因。这些基因的过表达导致脱落酸（ABA）水平升高，暗示ABA在sl介导的芽生长抑制中的作用。我们的研究结果表明，SLs通过调节ABA水平，通过MdSPL6及其下游靶标调控苹果腋芽生长，为植物结构的遗传控制提供了新的见解，并为培育分枝优化和产量提高的苹果品种提供了潜在的靶标。

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 生物-植物科学

CiteScore

12.20

自引率

5.40%

发文量

535

审稿时长

2.3 months

期刊介绍： Plant Physiology® is a distinguished and highly respected journal with a rich history dating back to its establishment in 1926. It stands as a leading international publication in the field of plant biology, covering a comprehensive range of topics from the molecular and structural aspects of plant life to systems biology and ecophysiology. Recognized as the most highly cited journal in plant sciences, Plant Physiology® is a testament to its commitment to excellence and the dissemination of groundbreaking research. As the official publication of the American Society of Plant Biologists, Plant Physiology® upholds rigorous peer-review standards, ensuring that the scientific community receives the highest quality research. The journal releases 12 issues annually, providing a steady stream of new findings and insights to its readership.