Roles of pepper bZIP protein CaDILZ1 and its interacting partner RING‐ ype E3 ligase CaDSR1 in modulation of drought tolerance

First author: Chae Woo Lim; Affiliations: Chung‐Ang University (韩国中央大学): Seoul, Republic of Korea

Corresponding author: Sung Chul Lee

Abscisic acid (ABA) is a plant hormone that plays a key role in the environmental stress response, especially induction of ABA‐ and stress‐ esponsive genes and modulation of the stomatal aperture (气孔开度) in response to drought stress. Here, we identified CaDILZ1 (Capsicum annuum 辣椒 Drought‐Induced Leucine Zipper 1) belonging to subgroup D of the bZIP protein family; gene functions of this family in response to ABA and drought signaling still remain unknown. CaDILZ1 expression was significantly induced in pepper leaves after exposure to ABA, drought, and NaCl. The CaDILZ1 protein localized in the nucleus of plant cells. In response to drought stress, CaDILZ1‐silenced pepper and CaDILZ1‐overexpressing Arabidopsis plants exhibited drought‐sensitive and drought‐ olerant phenotypes, respectively, via altered ABA content, stomatal closure, and expression of ABA‐ and drought‐ esponsive marker genes. We isolated the RING finger protein CaDSR1 (Capsicum annuum Drought Sensitive RING finger protein 1), which interacted with CaDILZ1 in the nucleus. The CaDSR1 protein exhibited E3 ligase activity and promoted CaDILZ1 degradation via the 26S proteasome pathway. Under drought stress conditions, CaDSR1‐silenced pepper and CaDSR1‐overexpressing Arabidopsis plants exhibited contrasting phenotypes to those of CaDILZ1‐silenced pepper and CaDILZ1‐overexpressing Arabidopsis plants. Taken together, our data suggest that CaDSR1 and CaDILZ1 function in ABA‐mediated drought stress signaling in pepper plants.

脱落酸ABA是植物中参与环境胁迫响应的重要激素，尤其是响应干旱条件调节ABA和胁迫响应基因及气孔开度。本文作者在辣椒中鉴定了bZIP转录因子家族D亚家族中一员CaDILZ1基因，该家族的基因在响应ABA和干旱信号方面的作用还不清楚。ABA、干旱或者NaCl处理辣椒均能显著诱导叶片中CaDILZ1基因的表达。CaDILZ1蛋白定位于植物细胞的细胞核中。在干旱胁迫下，CaDILZ1基因沉默的辣椒植株和CaDILZ1基因过表达的拟南芥植株通过改变植株中ABA含量、气孔闭合及aba和干旱响应基因的表达分别表现出干旱敏感和干旱耐受的表型特征。作者还分离出了甜椒中的干旱敏感环指蛋白CaDSR1，该蛋白与CaDILZ1蛋白在细胞核中互作。CaDSR1蛋白具有E3泛素酶的活性，通过26S蛋白酶体通路降解CaDILZ1蛋白。在干旱胁迫条件下，CaDSR1基因沉默和过表达的辣椒植株与CaDILZ1基因沉默和过表达的辣椒植株表现出完全相反的表型。综上，本文的研究显示CaDSR1和CaDILZ1蛋白共同作用于辣椒中由ABA介导的干旱胁迫信号。

doi: https://doi.org/10.1111/tpj.14046

Journal: the plant journal

First Published: 27 July, 2018

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