Cold stress response in Arabidopsis thalianais mediated by GNOM ARF-GEF

First author: Mohammad Arif Ashraf ; Affiliations: Iwate University (岩手大学): Morioka, Japan

Corresponding author: Abidur Rahman

Endosomal trafficking (内体运输) plays an important role in regulating plant growth and development both at optimal and stressed conditions. Cold stress response in Arabidopsis root is directly linked to inhibition of the endosomal trafficking of auxin efflux carriers. However, the cellular components that link cold stress and the endosomal trafficking remain elusive. By screening available endosomal trafficking mutants against root growth recovery response under cold stress, we identified GNOM, a SEC7 containing ARF‐GEF, as a major modulator of cold response. Contrasting response of partial loss of function mutant gnomB4049/emb30‐1 and the engineered Brefeldin A (BFA) resistant GNOM line, both of which contain mutations within SEC7 domain, to cold stress at whole plant level highlights the importance of this domain in modulating plants cold response pathway. Cold stress selectively and transiently (瞬时的) inhibits GNOM expression. The engineered point mutation at 696 amino acid position (Methionine to Leucine) that makes GNOM resistant to BFA, in fact results in overexpression of GNOM both at transcriptional and translational levels, and also alters its subcellular localization. Overexpression and altered cellular localization of GNOM were found to be directly linked to conferring striking cold resistant phenotype in Arabidopsis. Collectively, these results provide a mechanistic link between GNOM, BFA sensitive GNOM regulated trafficking and cold stress.

在合适和胁迫环境条件下，内体运输在调控植物的生长和发育中均发挥重要作用。拟南芥根的低温胁迫响应直接关联到生长素外流载体的内体运输。然而，具体的细胞内关联低温胁迫和内体运输的组件还不清楚。通过筛选低温胁迫下根生长恢复的内体运输突变体植株，作者鉴定到了一个含有SEC7的ARF‐GEF蛋白GNOM作为拟南芥中低温响应的主要调控子。部分功能突变体gnomB4049/emb30‐1和BFA抗性GNOM株系，这两者在SEC7结构域上均含有突变，且对于低温胁迫响应具有明显的差异，表明该结构域在调控植物低温胁迫响应通路中具有重要的作用。低温胁迫会选择性地瞬时抑制GNOM的表达。将GNOM上696位氨基酸蛋氨酸点突变为亮氨酸会产生BFA抗性，实际上会在转录和翻译水平过表达GNOM，并且还会改变GNOM的亚细胞定位。GNOM的过表达和亚细胞定位的改变与拟南芥对低温的抗性直接相关。综上，本文的研究结果显示GNOM调控的内体运输作用于植株的低温胁迫。

doi: https://doi.org/10.1111/tpj.14137

Journal: the plant journal

First Published: 26 October, 2018

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