BnaA03.WRKY28与BnaA09.VQ12相互作用，是激活的BnWRKY33介导的抗油菜菌核盘菌爆发的制动因子
油菜菌核病对甘蓝型油菜（Brassica napus，油菜）的生长造成严重危害，严重影响作物产量。植物天然免疫系统可能是油菜抗核盘菌的主要途径。本文，我们鉴定了BnWRKY33，一种天然免疫途径中的转录因子，在油菜感染核盘菌后可以被MAPK级联快速磷酸化和激活。在MAPK级联中，激活的BnaA03.MKK4磷酸化并激活BnaA06.MPK3和BnaC03.MPK3。激活的BnMPK3作用于底物BnWRKY33，增强其转录活性，触发BnWRKY33的转录爆发，通过增强植物抗毒素合成相关基因的表达，帮助植物有效抵抗病原真菌。在持续感染的情况下，BnaA03.WRKY28和BnaA09.VQ12被诱导，BnaA03.WRKY28与BnaA09.VQ12发生物理相互作用，形成蛋白质复合物。
在BnaA09.VQ12的帮助下，BnaA03.WRKY28优先结合BnWRKY33的启动子。与激活的BnWRKY33相比，BnaA03.WRKY28在BnWRKY33下游的转录活性较低，导致油菜在侵染后期对菌核病菌的抗性较弱。
此外，诱导的BnaA03.WRKY28可能通过调控分枝相关基因（如BnBRC1）的表达，促进腋芽活性和腋生分生组织的形成，从而促进叶腋分枝的形成。
Sclerotinia sclerotiorum causes substantial damage to the growth of Brassica napus (rapeseed) and makes a significant loss of crop yield. The plant innate immune system may be the primary solution to defense against S. sclerotiorum for rapeseed. Here, we identify that BnWRKY33, a transcription factor in the innate immune pathway, can be rapidly phosphorylated and activated by the MAPK cascade after rapeseed is infected with S. sclerotiorum. In the MAPK cascade, activated BnaA03.MKK4 phosphorylates and activates BnaA06.MPK3 and BnaC03.MPK3. The activated BnMPK3 acts on the substrate BnWRKY33 to enhance its transcriptional activity and trigger a transcriptional burst of BnWRKY33, which helps plants effectively resist the pathogenic fungi by enhancing the expression of phytoalexin synthesis-related genes. With constant infection, BnaA03.WRKY28 and BnaA09.VQ12 are induced, and BnaA03.WRKY28 physically interacts with BnaA09.VQ12 to form a protein complex. BnaA03.WRKY28 preferentially binds to the promoter of BnWRKY33 with the help of BnaA09.VQ12. Compared with activated BnWRKY33, BnaA03.WRKY28 has a lower transcriptional activity on downstream BnWRKY33, which leads to weaker resistance against S. sclerotiorum for rapeseed in the later stage of infection. Furthermore, the induced BnaA03.WRKY28 may promote axillary bud activity and axillary meristem initiation by regulating the expression of branching-related genes (such as BnBRC1), thus promoting the formation of branches in the leaf axils.
https://www.biorxiv.org/content/10.1101/2021.01.28.428601v1.full.pdf
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