Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China.
Plant Physiol. 2022 Feb 4;188(2):1277-1293. doi: 10.1093/plphys/kiab507.
Soybean mosaic virus (SMV) is a severe soybean (Glycine max) pathogen. Here we characterize a soybean SMV resistance cluster (SRC) that comprises five resistance (R) genes. SRC1 encodes a Toll/interleukin-1 receptor and nucleotide-binding site (TIR-NBS [TN]) protein, SRC4 and SRC6 encode TIR proteins with a short EF-hand domain, while SRC7 and SRC8 encode TNX proteins with a noncanonical basic secretory protein (BSP) domain at their C-termini. We mainly studied SRC7, which contains a noncanonical BSP domain and gave full resistance to SMV. SRC7 possessed broad-spectrum antiviral activity toward several plant viruses including SMV, plum pox virus, potato virus Y, and tobacco mosaic virus. The TIR domain alone was both necessary and sufficient for SRC7 immune signaling, while the NBS domain enhanced its activity. Nuclear oligomerization via the interactions of both TIR and NBS domains was essential for SRC7 function. SRC7 expression was transcriptionally inducible by SMV infection and salicylic acid (SA) treatment, and SA was required for SRC7 triggered virus resistance. SRC7 expression was posttranscriptionally regulated by miR1510a and miR2109, and the SRC7-miR1510a/miR2109 regulatory network appeared to contribute to SMV-soybean interactions in both resistant and susceptible soybean cultivars. In summary, we report a soybean R gene cluster centered by SRC7 that is regulated at both transcriptional and posttranscriptional levels, possesses a yet uncharacterized BSP domain, and has broad-spectrum antiviral activities. The SRC cluster is special as it harbors several functional R genes encoding atypical TIR-NBS-LRR (TNL) type R proteins, highlighting its importance in SMV-soybean interaction and plant immunity.
大豆花叶病毒（SMV）是一种严重的大豆（Glycine max）病原体。在这里，我们描述了一个大豆 SMV 抗性簇（SRC），该簇包含五个抗性（R）基因。SRC1 编码 Toll/白细胞介素-1 受体和核苷酸结合位点（TIR-NBS [TN]）蛋白，SRC4 和 SRC6 编码具有短 EF 手型结构域的 TIR 蛋白，而 SRC7 和 SRC8 编码具有非典型碱性分泌蛋白（BSP）结构域的 TNX 蛋白。我们主要研究了 SRC7，它包含一个非典型的 BSP 结构域，对 SMV 具有完全抗性。SRC7 对几种植物病毒（包括 SMV、李痘病毒、马铃薯 Y 病毒和烟草花叶病毒）具有广谱抗病毒活性。单独的 TIR 结构域既是 SRC7 免疫信号所必需的，也是其充分发挥作用所必需的，而 NBS 结构域则增强了其活性。通过 TIR 和 NBS 结构域的相互作用进行核寡聚化是 SRC7 功能所必需的。SRC7 的表达可被 SMV 感染和水杨酸（SA）处理转录诱导，SA 是触发 SRC7 抗病毒所必需的。SRC7 的表达受 miR1510a 和 miR2109 的转录后调控，SRC7-miR1510a/miR2109 调控网络似乎有助于抗性和敏感大豆品种中 SMV-大豆的相互作用。总之，我们报告了一个以 SRC7 为中心的大豆 R 基因簇，该基因簇在转录和转录后水平受到调控，具有尚未被表征的 BSP 结构域，并且具有广谱抗病毒活性。SRC 簇很特殊，因为它包含几个功能 R 基因，编码非典型的 TIR-NBS-LRR（TNL）型 R 蛋白，这突出了它在 SMV-大豆相互作用和植物免疫中的重要性。
