Jasmonic acid inhibits auxin-induced lateral rooting independently of the CORONATINE INSENSITIVE 1 receptor

First author: Yasuhiro Ishimaru; Affiliations: Tohoku University (日本東北大學): Sendai, Japan

Corresponding author: Minoru Ueda (上田実)

Plant root systems are indispensable (不可或缺的) for water uptake, nutrient acquisition (养分获取), and anchoring plants in the soil. Previous studies using auxin inhibitors definitively established that auxin plays a central role regulating root growth and development. Most auxin inhibitors affect all auxin signaling at the same time, which obscures (使…模糊不清) an understanding of individual events. Here, we report that jasmonic acid (JA) functions as a lateral root (LR)-preferential auxin inhibitor in Arabidopsis thaliana in a manner that is independent of the JA receptor, CORONATINE INSENSITIVE 1 (COI1). Treatment of wild-type Arabidopsis with either (-)-JA or (+)-JA reduced primary root length and LR number; the reduction of LR number was also observed in coi1 mutants. Treatment of seedlings with (-)-JA or (+)-JA suppressed auxin-inducible genes related to LR formation, diminished (减少) accumulation of the auxin reporter DR5::GUS, and inhibited auxin-dependent DII-VENUS degradation. A structural mimic of (-)-JA and (+)-coronafacic acid (冠菌酸) also inhibited LR formation and stabilized DII-VENUS protein. COI1-independent activity was retained in the double mutant of transport inhibitor response 1 and auxin signaling f-box protein 2 (tir1 afb2), but reduced in the afb5 single mutant. These results reveal JAs and (+)-coronafacic acid to be selective counter-auxins, a finding that could lead to new approaches for studying the mechanisms of LR formation.

植物根系统对于植物的水分吸收、养分获取及植物固定不可或缺。先前的研究通过生长素抑制剂证明了生长素在植物根的生长和发育中发挥重要作用。大多数的生长素抑制剂会同时影响所有的生长素信号，因此使得单个事件的解析变得模糊。本文报道了茉莉酸JA独立于茉莉酸的受体COI1作为侧根优先选择的生长素抑制因子在拟南芥中发挥作用。对野生型的拟南芥进行(-)-JA或(+)-JA的处理均能够减少主根的长度和侧根的数量，并且作者在coi1突变体中也检测到了侧根数量的减少。对拟南芥的幼苗进行(-)-JA或(+)-JA的处理会抑制生长素诱导型与侧根形成相关基因的表达，减少生长素报告基因DR5::GUS的积累，同时还会抑制依赖于生长素的DII-VENUS降解。一个(-)-JA和(+)-冠菌酸的结构模仿物质也能够抑制侧根的形成和稳定DII-VENUS蛋白。在转运抑制响应因子和生长素信号F-box蛋白tir1 afb2双突变体中，COI1非依赖型的活性得以保留，但在afb5单突变体中降低。这些结果表明茉莉酸和(+)-冠菌酸是生长素的可选择性抑制剂，这个发现可能会为研究侧根形成机制提供新的方法。

通讯：上田実 (http://linx.hzau.edu.cn/szxx/zzjs/gsx/jiaoshou/201403/t20140305_37532.htm)

研究方向：天然产物化学；新型生物活性天然产物；新型生物活性天然多糖的结构测定；生物活性配体与受体的相互作用；合成生物活性探针的化学生物学。

doi: https://doi.org/10.1104/pp.18.00357

Journal: Plant Physiology

First Published: 22 June, 2018

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