miR167-XsARF6-IAA 模块在文冠果雌蕊败育中的调控机制

Mechanism of the miR167- XsARF6-IAA regulatory module in pistil abortion in Xanthoceras sorbifolium

摘要

【目的】雌蕊败育是限制文冠果产量的关键因素，miR167 可能通过调控 ARF 基因参与生长素通路，但在文冠果雌蕊败育中的具体功能尚不清晰。本研究旨在探究文冠果雄花雌蕊败育过程中 miR167- XsARF-IAA 模块的调控机制，明确 IAA 通路关键基因 XsARF6 受 miR167 调控的功能，以期为解析文冠果雌蕊败育的调控机制奠定前期理论基础。【方法】以文冠果雌雄花 3 个关键发育时期的雌蕊为材料，开展全转录组测序，联合 miRNA 与 mRNA 数据分析筛选关键 xso-miR167；结合生物学验证及激素测定，分析 miRNA 与 mRNA 表达特征，测定过表达文冠果种仁 IAA 含量及转基因拟南芥表型，阐明 miR167- XsARF-IAA 的动态调控机制。【结果】（1）在雄花雌蕊败育 3 个关键时期共鉴定出 481 个 miRNA，预测靶基因 2 266 个，差异 miRNA 表达具有明显阶段特异性，表明不同 miRNA 在败育进程中发挥关键调控作用。（2）雄花雌蕊发育过程中 xso-miR167 表达持续升高，显著抑制靶基因 XsARF6.2 表达，表达趋势呈负相关，推测这一调控对是雌蕊败育的关键因素之一。（3）xso-miR167 过表达文冠果种仁 IAA 含量显著低于野生型与空载体对照。（4）在拟南芥中过表达 xso-miR167，花粉活力从 90.9% 降至 43.68% 和 62.25%，同时柱头直径、雌雄蕊长度显著缩短，且开花延迟，花器官发育异常。【结论】文冠果雄花雌蕊中存在 miR167- XsARF-IAA 调控模块，miR167 通过抑制 XsARF6.2 表达，影响 IAA 的合成、代谢或转运过程，进而在雌蕊败育中发挥关键作用。研究为揭示生长素调控文冠果雌蕊发育的分子机制提供了新视角，为相关基础研究与育种应用提供理论依据。

Abstract

[Objective] Pistil abortion is a key factor limiting Xanthoceras sorbifolium yield. miR167 may participate in the auxin pathway by regulating ARF genes, but its specific function in the pistil abortion of Xanthoceras sorbifolium remains to be elucidated. This study aimed to investigate the regulatory mechanism of the miR167- XsARF-IAA module during pistil abortion in male flowers of X. sorbifolium Bunge, and to clarify the function of the key IAA pathway gene XsARF6 regulated by miR167, so as to lay a preliminary theoretical foundation for dissecting the regulatory mechanism of pistil abortion in this species. [Method] Pistils of female and male flowers at three key developmental stages were sampled for whole-transcriptome sequencing. The key xso-miR167 was identified by integrated miRNA and mRNA analyses. Biological validation and hormone measurement were performed to analyze the expression patterns of miRNAs and mRNAs were analyzed. IAA content in kernels of X. sorbifolium overexpressing xso-miR167 and phenotypes of transgenic Arabidopsis thaliana were determined to elucidate the dynamic regulation of the miR167- XsARF-IAA module. [Result] (1) A total of 481 miRNAs and 2 266 predicted target genes were identified across the three key stages of pistil abortion, with differentially expressed miRNAs showing clear stage-specific patterns, indicating that different miRNAs play critical regulatory roles during the abortion process. (2) The expression of xso-miR167 increased continuously during pistil development in male flowers, significantly repressing its target gene XsARF6.2, and their expression trends were negatively correlated, suggesting that this regulatory pair is a key factor in pistil abortion. (3) xso-miR167 overexpression significantly decreased kernel IAA content compared with wild-type and empty-vector controls. (4) In transgenic A. thaliana, pollen viability decreased from 90.9% in the wild type to 43.68% and 62.25%, stigma diameter and lengths of pistils and stamens were significantly reduced, flowering was delayed, and floral organ development was abnormal. [Conclusion] The miR167- XsARF-IAA regulatory module exists during pistil development in male flowers of X. sorbifolium. miR167 participates in regulating the biosynthesis, metabolism or transport of IAA by inhibiting the expression of XsARF6.2 , and plays a key role in pistil abortion of X. sorbifolium. This study provides a new perspective on the molecular mechanism of auxin-regulated pistil development in X. sorbifolium and offers a theoretical basis for fundamental research and breeding applications.

关键词

文冠果 / 雌蕊败育 / miR167 / 生长素响应因子 (ARF6) / 生长素 (IAA) / 异源转化 / 生殖发育 / 转录后调控

Key words

Xanthoceras sorbifolium / pistil abortion / miR167 / auxin response factor (ARF6) / indole-3-acetic acid (IAA) / heterologous transformation / reproductive development / post-transcriptional regulation

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基金资助

国家自然科学基金项目(32572006)

国家重点研发计划(2024YFD2201101-6)

中央高校基本科研业务费专项(2025XJ04)