OsMADS25 regulates root system development via auxin signaling in rice

First author: Guopeng Zhang; Affiliations: Chongqing University (重庆大学): Chongqing, China

Corresponding author: Junli Huang (黄俊丽)

The phytohormone auxin is essential for root development in plants. OsMADS25 is a homolog of the AGL17-clade MADS-box genes in rice. In spite of recent progress, the molecular mechanisms underlying the regulation of root development by OsMADS25 are not well known. It is unclear whether OsMADS25 regulates root development via auxin signaling. In this study, we examined the role of OsMADS25 in root development and characterized the signaling pathway through which OsMADS25 regulates root system development in rice. OsMADS25 overexpression significantly increased, but RNAi gene silencing repressed primary root (PR) length and lateral root (LR) density. Moreover, OsMADS25 promoted LR development in response to NO3–. Further study showed that OsMADS25 increased auxin accumulation in the root system by enhancing auxin biosynthesis and transport, while also reducing auxin degradation, thus stimulating root development. More importantly, OsMADS25 was found to regulate OsIAA14 expression directly by binding to the CArG-box in the promoter region of OsIAA14, which encodes an Aux/IAA transcriptional repressor of auxin signaling. Elevated auxin levels and decreased OsIAA14 expression might lead to reduced OsIAA14 protein accumulation, as a mechanism to regulate auxin signaling. Therefore, our findings reveal a molecular mechanism by which OsMADS25 modulates root system growth and development in rice, at least partilly, via Aux/IAA-based auxin signaling.

植物激素生长素对于植物根的发育至关重要。OsMADS25基因是水稻中AGL17类MADS-box基因的旁系同源基因。目前对于植物根中OsMADS25基因是通过什么样的分子机制来调控根的发育还不清楚。OsMADS25基因是否需要通过生长素信号来调控根的发育也不清楚。本文，作者研究了OsMADS25基因在根发育中的作用，并鉴定了水稻中通过OsMADS25基因调控根系统发育的信号通路。OsMADS25基因过表达会显著提高主根长度和侧根密度，而RNAi干扰株系则完全相反。此外，OsMADS25基因会响应硝酸根离子促进侧根的发育。进一步的研究显示OsMADS25基因通过增强生长素的合成和运输增加了生长素在根中的积累，同时OsMADS25基因还能减少生长素的降解，进而促进根的发育。作者还发现OsMADS25蛋白能够直接结合到OsIAA14基因启动子区的CArG-box从而调控OsIAA14基因的表达，而OsIAA14基因又是生长素信号的Aux/IAA转录抑制子。升高的生长素水平和降低的OsIAA14基因表达可能导致了OsIAA14蛋白积累的减少，从而起到调控生长素信号的作用。因此，本文的发现揭示了OsMADS25通过基于Aux/IAA的生长素信号通路调控水稻根生长和发育的分子机制。

通讯：黄俊丽 (http://bio.cqu.edu.cn/info/1018/1162.htm)

个人简介：2003年，中国农业大学，博士；2008-2009年，美国Purdue University，访问学者。

研究方向：分子生物学与基因工程；植物生长发育调控；植物抗逆分子机制。

doi: https://doi.org/10.1111/tpj.14007

Journal: the plant journal

First Published: 22 June, 2018

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