The whitefly Bemisia tabaci is a destructive agricultural pest that frequently harbors various species of secondary symbionts including Rickettsia. Previous studies have revealed that the infection of Rickettsia can improve whitefly performance on food plants; however, to date, no evidence has shown, if, and how, Rickettsia manipulates the plant-insect interactions. In the current study, the effects of Rickettsia persistence on the induced plant defenses and the consequent performance of whitefly B. tabaci were investigated. Results revealed that Rickettsia can be transmitted into plants via whitefly feeding and remain alive within the cotton plants for at least 2 weeks. The different expression genes of cotton plants were mostly concentrated in the phytohormone signaling pathways, the marker genes of jasmonic-acid signaling pathway (AOC, AOS, LOX, MYC2) were significantly downregulated, while the marker genes of the salicylic-acid signaling pathway (WRKY70, PR-1) were upregulated. Biological experiments revealed that the fecundity of Rickettsia negative B. tabaci significantly increased when they fed on Rickettsia-persistent cotton plants. Taken together, we provide experimental evidence that the persistence of Rickettsia and its induced defense responses in cotton plants can increase the fitness of whitefly and, by this, Rickettsia may increase its infection and spread within its whitefly host.

中文翻译：

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立克次体通过操纵寄主植物的防御模式增加其在粉虱种群中的感染和传播

粉虱 Bemisia tabaci 是一种破坏性的农业害虫，经常携带各种次生共生体，包括立克次体。以前的研究表明，立克次体的感染可以提高粉虱在食用植物上的表现；然而，迄今为止，没有证据表明立克次体是否以及如何操纵植物与昆虫的相互作用。在目前的研究中，研究了立克次体持久性对诱导植物防御的影响以及粉虱 B. tabaci 的后续性能。结果表明，立克次体可以通过粉虱摄食传播到植物中，并在棉花植物中存活至少 2 周。棉花植株不同表达基因主要集中在植物激素信号通路、茉莉酸信号通路标志基因（AOC、AOS、LOX、MYC2）显着下调，而水杨酸信号通路的标志基因（WRKY70，PR-1）上调。生物学实验表明，以立克次体持久性棉花为食，立克次体阴性烟粉虱的繁殖力显着增加。总之，我们提供的实验证据表明，立克次体的持续存在及其在棉花植物中诱导的防御反应可以增加粉虱的适应性，因此，立克次体可能会增加其在粉虱宿主内的感染和传播。