PbrBZR1 interacts with PbrARI2.3 to mediate brassinosteroid-regulated pollen tube growth during self-incompatibility signaling in pear

文献类型： 外文期刊

第一作者： Wang, Yicheng

作者： Wang, Yicheng;Liu, Panpan;Cai, Yiling;Li, Yu;Tang, Chao;Zhu, Nan;Wang, Peng;Zhang, Shaoling;Wu, Juyou;Wu, Juyou

作者机构：

期刊名称：PLANT PHYSIOLOGY （ 影响因子：7.4； 五年影响因子：8.7 ）

ISSN： 0032-0889

年卷期： 2023 年 192 卷 3 期

页码：

收录情况： SCI

摘要： S-RNase-mediated self-incompatibility (SI) prevents self-fertilization and promotes outbreeding to ensure genetic diversity in many flowering plants, including pear (Pyrus sp.). Brassinosteroids (BRs) have well-documented functions in cell elongation, but their molecular mechanisms in pollen tube growth, especially in the SI response, remain elusive. Here, exogenously applied brassinolide (BL), an active BR, countered incompatible pollen tube growth inhibition during the SI response in pear. Antisense repression of BRASSINAZOLE-RESISTANT1 (PbrBZR1), a critical component of BR signaling, blocked the positive effect of BL on pollen tube elongation. Further analyses revealed that PbrBZR1 binds to the promoter of EXPANSIN-LIKE A3 (PbrEXLA3) to activate its expression. PbrEXLA3 encodes an expansin that promotes pollen tube elongation in pear. The stability of dephosphorylated PbrBZR1 was substantially reduced in incompatible pollen tubes, where it is targeted by ARIADNE2.3 (PbrARI2.3), an E3 ubiquitin ligase that is strongly expressed in pollen. Our results show that during the SI response, PbrARI2.3 accumulates and negatively regulates pollen tube growth by accelerating the degradation of PbrBZR1 via the 26S proteasome pathway. Together, our results show that an ubiquitin-mediated modification participates in BR signaling in pollen and reveal the molecular mechanism by which BRs regulate S-RNase-based SI.

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