A faster killing effect of plastid-mediated RNA interference on a leaf beetle through induced dysbiosis of the gut bacteria

The expression of double-stranded RNAs(dsRNAs)from the plastid genome has been proven to be an effective method for controlling herbivorous pests by targeting essential insect genes.However,there are limitations to the efficiency of plastid-mediated RNA interference(PM-RNAi)due to the initial damage caused by the insects and their slow response to RNA interference.In this study,we developed transplastomic poplar plants that express dsRNAs targeting the b-Actin(dsACT)and Srp54k(dsSRP54K)genes of Plagiodera versicolora.Feeding experiments showed that transplastomic poplar plants can cause significantly higher mortality in P.versicolora larvae compared with nuclear transgenic or wild-type poplar plants.The efficient killing effect of PM-RNAi on P.versicolora larvae was found to be dependent on the presence of gut bacteria.Importantly,foliar application of a gut bacterial strain,Pseudomonas putida,will induce dysbiosis in the gut bacteria of P.versicolora larvae,leading to a significant acceleration in the speed of killing by PM-RNAi.Overall,our findings suggest that interfering with gut bacteria could be a promising strategy to enhance the effectiveness of PM-RNAi for insect pest control,offering a novel and effective approach for crop protection based on RNAi technology.