State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo 315211, China.
Plant Cell. 2020 Sep;32(9):2806-2822. doi: 10.1105/tpc.19.00499. Epub 2020 Jun 25.
The crosstalk between brassinosteroid (BR) and jasmonic acid (JA) signaling is crucial for plant growth and defense responses. However, the detailed interplay between BRs and JA remains obscure. Here, we found that the rice () Glycogen synthase kinase3 (GSK3)-like kinase OsGSK2, a conserved kinase serving as a key suppressor of BR signaling, enhanced antiviral defense and the JA response. We identified a member of the JASMONATE ZIM-domain (JAZ) family, OsJAZ4, as a OsGSK2 substrate and confirmed that OsGSK2 interacted with and phosphorylated OsJAZ4. We demonstrated that OsGSK2 disrupted the OsJAZ4-OsNINJA complex and OsJAZ4-OsJAZ11 dimerization by competitively binding to the ZIM domain, perhaps helping to facilitate the degradation of OsJAZ4 via the 26S proteasome pathway. We also showed that OsJAZ4 negatively modulated JA signaling and antiviral defense and that the BR pathway was involved in modulating the stability of OsJAZ4 protein in an -dependent manner. Collectively, these results suggest that OsGSK2 enhances plant antiviral defenses by activating JA signaling as it directly interacts with, phosphorylates, and destabilizes OsJAZ4. Thus, our findings provide a clear link between BR and JA signaling.
油菜素内酯（BR）和茉莉酸（JA）信号转导之间的串扰对于植物生长和防御反应至关重要。然而，BR 和 JA 之间的详细相互作用仍然不清楚。在这里，我们发现水稻（）Glycogen synthase kinase3（GSK3）样激酶 OsGSK2，一种作为 BR 信号关键抑制因子的保守激酶，增强了抗病毒防御和 JA 反应。我们鉴定了 JASMONATE ZIM 结构域（JAZ）家族的一个成员，OsJAZ4，作为 OsGSK2 的底物，并证实 OsGSK2 与 OsJAZ4 相互作用并磷酸化 OsJAZ4。我们证明 OsGSK2 通过竞争结合 ZIM 结构域破坏了 OsJAZ4-OsNINJA 复合物和 OsJAZ4-OsJAZ11 二聚体，这可能有助于通过 26S 蛋白酶体途径促进 OsJAZ4 的降解。我们还表明，OsJAZ4 负调控 JA 信号和抗病毒防御，BR 途径参与以依赖的方式调节 OsJAZ4 蛋白的稳定性。总之，这些结果表明 OsGSK2 通过直接相互作用、磷酸化和使 OsJAZ4 失稳来激活 JA 信号，从而增强植物的抗病毒防御能力。因此，我们的研究结果提供了 BR 和 JA 信号之间的明确联系。
