The 30th International Conference on Arabidopsis Research (ICAR 2019)

563 / 2019-03-18 14:51:05

Trans-kingdom RNAi in plant-bacterial pathogen interactions

RNA silencing, plant immunity

Plenary track > RNA Biology

During the last decade, small RNAs have emerged as critical fine-tuners of plant immune responses. For example, we and others have shown that a subset of Arabidopsis microRNAs (miRNAs) are differentially expressed upon bacterial PAMP detection to orchestrate antibacterial immunity. In addition, we have reported a major role of the Arabidopsis miRNA pathway in PAMP-Triggered Immunity (PTI) and, as a corollary, have identified bacterial effectors from Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000) that suppress this small RNA pathway to cause disease. In the present work, we wanted to extend these findings by investigating whether host-encoded small RNAs could not only fine-tune plant immunity but also reprogram Pst DC3000 gene expression as part of an antibacterial defense response. This intriguing hypothesis would suggest that plant small RNAs and/or double-stranded RNA (dsRNAs) must be capable of passing through both the host plasma membrane and the double membrane of the bacterial cell envelope, and subsequently trigger gene silencing in this Gram-negative bacterium, which does not possess canonical eukaryotic-like RNA silencing factors. Here, I will provide experimental evidence for such Antibacterial Gene Silencing (AGS) phenomenon in the context of infection. I will additionally report on the plant RNA entities that are taken-up by Pst DC3000 cells and causal for trans-kingdom RNAi.