ELF18-INDUCED LONG-NONCODING RNA Associates with Mediator to Enhance Expression of Innate Immune Response Genes in Arabidopsis

Abstract

The plant immune response is a complex process involving transcriptional and posttranscriptional regulation of gene expression. Responses to plant immunity are initiated upon the perception of pathogen-associated molecular patterns, including peptide fragment of bacterial flagellin (flg22) or translation elongation factor Tu (elf18). Here, we identify an <i>Arabidopsis thaliana</i> long-noncoding RNA, designated ELF18-INDUCED LONG-NONCODING RNA1 (ELENA1), as a factor enhancing resistance against <i>Pseudomonas syringe</i> pv <i>tomato</i> DC3000. ELENA1 knockdown plants show decreased expression of <i>PATHOGENESIS-RELATED GENE1</i> (<i>PR1</i>) and the plants are susceptible to pathogens. By contrast, plants overexpressing ELENA1 show elevated <i>PR1</i> expression after elf18 treatment and display a pathogen resistance phenotype. RNA-sequencing analysis of ELENA1-overexpressing plants after elf18 treatment confirms increased expression of defense-related genes compared with the wild type. ELENA1 directly interacts with Mediator subunit 19a (MED19a) and affects enrichment of MED19a on the <i>PR1</i> promoter. These results show that MED19a regulates <i>PR1</i> expression through ELENA1. Our findings uncover an additional layer of complexity, implicating long-noncoding RNAs in the transcriptional regulation of plant innate immunity.