An atypical EF-hand domain containing resistance protein SRC4 boosts plant immunity in a calcium-enhanced manner

IF 6.2 1区生物学 Q1 PLANT SCIENCES

The Plant Journal Pub Date : 2026-09-15 DOI:10.1111/tpj.71125

Zikai Zhou, Di Miao, Jie Zhao, Yuxi Zhou, Ting Yan, Niu Niu, Zhuo Bao, Fangjiao Lv, Lu Liu, Ning Xu, Fang Yan, Jun Liu, Hada Wuriyanghan

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引用次数: 0

Abstract

The typical nucleotide-binding leucine-rich repeat (NLR) proteins, such as TIR-NBS-LRR (TNL) and CC-NBS-LRR (CNL), are known to be engaged in effector-triggered immunity (ETI). However, several atypical resistance (R) proteins with truncated NLR domains or with nonclassical domains are emerging to be key regulators in plant immunity. SMV resistance cluster 4 (SRC4) is an atypical NLR protein in soybean, distinguished by an N-terminal Domain (NTD)-TIR-shortened NBS oligomerization region (SNOR)-EF-hand (EFh) domain architecture. SRC4 lacks both NBS and LRR domains but retains basal antiviral activity through its TIR-SNOR region, with SNOR contributing to TIR-dependent antiviral activity and SRC4 self-association. The EFh domain recognizes coat protein (CP) of soybean mosaic virus (SMV) and serves as a Ca²⁺-responsive module to distinctly regulate TIR-SNOR-mediated immune response in soybean. SRC4-overexpression (Ox-SRC4) soybean plants show SMV resistance without obvious growth penalty. Furthermore, several SRC4 high-expression soybean varieties showed stronger SMV resistance and Ca²⁺ responsiveness than the SRC4 low-expression soybean varieties. Our study highlights the essential roles of atypical resistance proteins in plant immunity and growth-defense balance.

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含有抗性蛋白SRC4的非典型EF-hand结构域以钙增强的方式增强植物免疫。

典型的核苷酸结合富亮氨酸重复序列（NLR）蛋白，如TIR-NBS-LRR （TNL）和CC-NBS-LRR (CNL)，已知参与效应触发免疫（ETI）。然而，一些具有截断NLR结构域或具有非经典结构域的非典型抗性(R)蛋白正在成为植物免疫的关键调节因子。SMV抗性簇4 （SRC4）是大豆非典型NLR蛋白，具有n端结构域(NTD)- tir -缩短的NBS寡聚区(SNOR)-EF-hand （EFh）结构域结构。SRC4缺乏NBS和LRR结构域，但通过其TIR-SNOR区域保持基本的抗病毒活性，SNOR有助于tir依赖性抗病毒活性和SRC4的自结合。EFh结构域识别大豆花叶病毒（SMV）外壳蛋白（CP），并作为Ca2+响应模块明显调节tir - snorr介导的大豆免疫应答。src4过表达（Ox-SRC4）的大豆植株表现出SMV抗性，但没有明显的生长损失。此外，一些SRC4高表达大豆品种比SRC4低表达大豆品种表现出更强的SMV抗性和Ca2+响应性。我们的研究强调了非典型抗性蛋白在植物免疫和生长防御平衡中的重要作用。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

The Plant Journal 生物-植物科学

CiteScore

13.10

自引率

4.20%

发文量

415

审稿时长

2.3 months

期刊介绍： Publishing the best original research papers in all key areas of modern plant biology from the world"s leading laboratories, The Plant Journal provides a dynamic forum for this ever growing international research community. Plant science research is now at the forefront of research in the biological sciences, with breakthroughs in our understanding of fundamental processes in plants matching those in other organisms. The impact of molecular genetics and the availability of model and crop species can be seen in all aspects of plant biology. For publication in The Plant Journal the research must provide a highly significant new contribution to our understanding of plants and be of general interest to the plant science community.