1 Plant Biology Section, School of Integrated Plant Science, Cornell University, Ithaca, NY 14853, U.S.A.
2 Xinjiang Key Laboratory of Crop Biotechnology, Institute of Nuclear and Biological Technology, Xinjiang Academy of Agricultural Sciences, Urumuqi 830091, China.
Mol Plant Microbe Interact. 2017 Apr;30(4):334-342. doi: 10.1094/MPMI-02-17-0041-R. Epub 2017 Apr 14.
The small ubiqutin-like modifier E3 ligase SIZ1 regulates multiple processes in Arabidopsis, including salicylic-acid-dependent immune responses. However, the targets of SIZ1 in plant immunity are not known. Here, we provide evidence that the plant immune receptor nucleotide-binding leucine-rich repeat gene SNC1 partially mediates the regulation of plant immunity by SIZ1. The siz1 loss-of-function mutant has an autoimmune phenotype that is dependent on SNC1 and temperature. Overexpression of SIZ1 partially rescues autoimmune mutant phenotypes induced by activation or overaccumulation of SNC1, and the SNC1 protein amount is attenuated by SIZ1 overexpression. In addition, overexpression of the F-box protein CPR1 that degrades the SNC1 protein inhibits the growth defects and disease resistance of the siz1 mutant. Furthermore, we found that the SNC1 protein is sumoylated in planta. Although it remains to be determined whether SIZ1 primarily modulates the SNC1 protein via sumoylation or affects SNC1 transcript level, our data indicate that SNC1 is a major mediator of defense response modulated by SIZ1 and that SNC1 is a crucial target for fine-tuning plant defense responses.
小泛素样修饰酶 E3 连接酶 SIZ1 调节拟南芥中的多个过程，包括依赖水杨酸的免疫反应。然而，SIZ1 在植物免疫中的靶标尚不清楚。在这里，我们提供的证据表明，植物免疫受体核苷酸结合富含亮氨酸重复基因 SNC1 部分介导 SIZ1 对植物免疫的调节。siz1 功能丧失突变体具有自身免疫表型，该表型依赖于 SNC1 和温度。SIZ1 的过表达部分挽救了由 SNC1 的激活或过积累诱导的自身免疫突变体表型，并且 SIZ1 的过表达减弱了 SNC1 蛋白的量。此外，降解 SNC1 蛋白的 F-box 蛋白 CPR1 的过表达抑制了 siz1 突变体的生长缺陷和抗病性。此外，我们发现 SNC1 蛋白在体内被 SUMO 化。尽管仍需要确定 SIZ1 是否主要通过 SUMO 化来调节 SNC1 蛋白，或者是否影响 SNC1 转录本水平，但我们的数据表明 SNC1 是 SIZ1 调节的防御反应的主要介质，并且 SNC1 是精细调节植物防御反应的关键靶标。
