Genetics/Genomics

Abstract

CS-17-5 - Secondary small RNAs contribute to host-induced gene silencing in oomycete pathogens

Monday, July 16
4:38 PM - 4:58 PM

Constantly facing challenges from potential pathogens in the environment, plants have evolved a myriad of defense mechanisms. Increasing evidence has emerged to suggest that small RNAs (sRNAs) are integral components of plant immunity. As a counter-defense strategy, pathogens have evolved the ability to interfere with host sRNA pathways. We previously identified secreted effector proteins from the destructive Phytophthora pathogens that can suppress RNA silencing in plant hosts. Here, we report the investigation of mechanisms underlying the virulence activity of the effector Phytophthora suppressor of RNA silencing 2 (PSR2), which allowed us to identify a specific sRNA pathway that is particularly important for defense response in Arabidopsis. In particular, secondary small interfering RNAs (siRNAs) generated from transcripts of pentatricopeptide-repeat proteins (PPRs)-encoding genes and triggered by the parent microRNA miR161 contribute to disease resistance by silencing specific genes in Phytophthora, thereby reducing their virulence. miR161 is induced during Phytophthora infection, leading to increased production of PPR-derived secondary siRNAs as the executors of a host-induced gene silencing. However, this defense mechanism is compromised by Phytophthora through the virulence activity of PSR2, which targets Double-stranded RNA-binding protein 4 (DRB4) and specifically impairs the biogenesis of secondary siRNAs derived from protein-coding transcripts. This study discovers a role of secondary siRNAs in plant immunity and establishes a new paradigm of host-pathogen arms race.


 

Co-Authors

Yi Zhai, co-first – UC Riverside; Li Feng – Southern University of Science and Technology, China ; Liping Zeng – UC Riverside; Du Seok Choi – UC Riverside; Bailong Zhang – UC Riverside; Weifeng Gu – UC Riverside; Xuemei Chen – UC Riverside; Wenwu Ye – Nanjing Agricultural University, China; Jixian Zhai – Southern University of Science and Technology, China; Wenbo Ma, corresponding author – UC Riverside

Yingnan Hou

Postdoc
UC Riverside

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CS-17-5 - Secondary small RNAs contribute to host-induced gene silencing in oomycete pathogens



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