烽火狼烟:水杨酸甲酯介导的植物间通讯和气传性免疫的机制解析

Study Uncovers a New Signaling Circuit Mediating Airborne Defense of Plants Against Aphids and Viruses

蚜虫(aphids)及其携带的病毒是全球农作物生产过程中最具破坏性的病虫害之一。植物一旦被蚜虫侵染,会产生并释放挥发性有机化合物(VOCs),进而通过空气传播至周围植物,激活邻近植物对昆虫和病毒的抗性,称为气传性免疫(AD)。而对于植物如何产生挥发性信号分子以及邻近植物如何感知并激活抗病虫的机制尚不清楚。近期,清华大学刘玉乐研究团队在植物间通讯介导邻近植物抗虫和抗病毒研究方面取得了新突破,他们揭示了一条由水杨酸甲酯(MeSA)-水杨酸结合蛋白SABP2-转录因子NAC2-水杨酸羧基甲基转移酶SAMT1组成的信号通路介导邻近植物抗虫和抗病毒能力。该研究还发现由蚜虫传播的一些病毒编码蛋白能够通过与NAC2转录因子互作促进NAC2的出核和降解,从而破坏植物间的信号交流以促进蚜虫及病毒的侵染。该研究全面阐释了蚜虫与其传播的病毒间共同进化的新的互惠关系,填补了植物抗病虫、特别是气传性免疫领域的空白,同时为培育抗虫、抗病毒作物提供了新思路及潜在基因。

Aphids and the viruses transmitted by them cause some of the most devastating plant diseases across the globe.Once infected by aphids,plants can produce and release volatile organic compounds(VOCs),which are transmitted through air and elicit defense in neighboring plants(airborne defense,AD).However,the mechanisms underlying AD remained largely elusive.Dr.Yule Liu’s group at Tsinghua University,China,recently reports a new study and they identify a new signaling circuit,comprising methyl-salicylate(MeSA),salicylic-acid(SA)-binding protein-2(SABP2),a transcription factor NAC2 and SA-carboxylmethyltransferase-1(SAMT1)converting SA to MeSA,that mediate interplant communication and airborne defense against aphids and viruses.Furthermore,some virus-encoded virulence proteins could interact with NAC2 transcription factor to reduce the nuclear localization and promotes the degradation of NAC2,thereby suppressing the interplant AD and promoting viral transmission.This comprehensive study provides new mechanistic insights into airborne defense of plants and unravels an amazing aphid/virus co-evolutionary mutualism.It also sets the foundation for new approaches of using AD to control aphid and virus diseases in agriculturally-important plants.