Rickettsia increases its infection and spread in whitefly populations by manipulating the defense patterns of the host plant.

Abstract

The whitefly Bemisia tabaci is a destructive agricultural pest that frequently harbours 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 at least two 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 down-regulated, while the marker genes of the salicylic-acid signaling pathway (WRKY70, PR-1) were up-regulated. Biological experiments revealed that the fecundity of Rickettsia negative B. tabaci significantly increased when they fed on Rickettsia persistent cotton plants. Taken together, we provided experimental evidences that the persistence of Rickettsia and it 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.