Yi Ge, Wu Wei, Wei Taiyun
State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China.
Front Microbiol. 2021 May 5;12:662577. doi: 10.3389/fmicb.2021.662577. eCollection 2021.
Rice gall dwarf virus (RGDV) and its leafhopper vector are plant phloem-inhabiting pests. Currently, how the delivery of plant viruses into plant phloem piercing-sucking insects modulates callose deposition to promote viral transmission remains poorly understood. Here, we initially demonstrated that nonviruliferous preferred feeding on RGDV-infected rice plants than viruliferous counterpart. Electrical penetration graph assay showed that viruliferous encountered stronger physical barriers than nonviruliferous insects during feeding, finally prolonging salivary secretion and ingestion probing. Viruliferous feeding induced more defense-associated callose deposition on sieve plates of rice phloem. Furthermore, RGDV infection significantly increased the cytosolic Ca level in rice plants, triggering substantial callose deposition. Such a virus-mediated insect feeding behavior change potentially impedes insects from continuously ingesting phloem sap and promotes the secretion of more infectious virions from the salivary glands into rice phloem. This is the first study demonstrating that the delivery of a phloem-limited virus by piercing-sucking insects into the plant phloem activates the defense-associated callose deposition to enhance viral transmission.
水稻瘤矮病毒（RGDV）及其叶蝉传播介体是寄生于植物韧皮部的害虫。目前，关于刺吸式昆虫如何将植物病毒传递到植物韧皮部从而调节胼胝质沉积以促进病毒传播，仍知之甚少。在此，我们首次证明无毒叶蝉比带毒叶蝉更倾向于取食感染RGDV的水稻植株。刺探电位图谱分析表明，带毒叶蝉在取食过程中比无毒叶蝉遇到更强的物理屏障，最终延长了唾液分泌和取食刺探时间。带毒叶蝉取食诱导水稻韧皮部筛板上更多与防御相关的胼胝质沉积。此外，RGDV感染显著提高了水稻植株胞质钙水平，引发大量胼胝质沉积。这种病毒介导的昆虫取食行为变化可能阻碍昆虫持续摄取韧皮部汁液，并促进更多感染性病毒粒子从唾液腺分泌到水稻韧皮部。这是第一项证明刺吸式昆虫将韧皮部受限病毒传递到植物韧皮部会激活与防御相关的胼胝质沉积以增强病毒传播的研究。
