Multi-Omics Analysis Reveals the Dynamic Changes of RNA N 6 -Methyladenosine in Pear (Pyrus bretschneideri) Defense Responses to Erwinia amylovora Pathogen Infection.

Chenyang Han,Qinhai Qiao,Xin Qiao,Yancun Zhao,Feng Zhang,Shaoling Zhang,Xiaosan Huang

doi:10.3389/fmicb.2021.803512

Abstract

N6-methylated adenine (m6A) is the most prevalent modification of mRNA methylation and can regulate many biological processes in plants, such as mRNA processing, development, and stress response. Some studies have increased our understanding of its various roles in model plants in recent years. Nevertheless, the distribution of m6A and the impact of m6A on the regulation of plant defense responses against pathogen inoculation are virtually unknown in pear. In this study, MeRIP-seq and RNA-seq data from healthy and inoculated plants were analyzed to assess the changes in the transcript levels and posttranscriptional modification of pear in response to the fire blight pathogen Erwinia amylovora. Following the analysis of 97,261 m6A peaks, we found that m6A preferred to modify duplicate genes rather than singleton genes and that m6A-methylated genes underwent stronger purifying selection. A total of 2,935 specific m6A sites were detected at the transcriptome level after inoculation, which may increase defense-related transcript abundance to enhance pear resistance. In addition, 1,850 transcripts were detected only in the mock-inoculated groups. The hypomethylated transcripts were mainly related to transcriptional regulation and various biological processes, such as chloroplast organization and sucrose biosynthetic processes. In addition, we found that the extent of m6A methylation was significantly positively correlated with the transcript level, suggesting a regulatory role for m6A in the plant response.

Highlights

Posttranscriptional modification is an important posttranscriptional regulatory mechanism through which RNA transcripts can be ensured to work normally at any given time (Wang et al, 2018; Arribas-Hernandez and Brodersen, 2020)
To begin studying the possibility that pear responds to fire blight, we inoculated Erwinia amylovora into pear seedlings, and LB liquid medium was inoculated to serve as a mock inoculation
Disease symptoms developed at 12 h post-inoculation (HPI), and mild lesions were observed at the inoculation site (Figure 1A)

Summary

Introduction

Posttranscriptional modification is an important posttranscriptional regulatory mechanism through which RNA transcripts can be ensured to work normally at any given time (Wang et al, 2018; Arribas-Hernandez and Brodersen, 2020). M6A modification is a dynamically reversible process regulated by a number of proteins, including methyltransferases (writers), demethylases (erasers), and m6A-binding proteins (readers), which act synergistically to regulate the abundance of m6A (Dominissini et al, 2012; Luo et al, 2014; Yue et al, 2019). M6A readers exert a more specific regulatory function by binding m6A modification sites on RNA (Dominissini et al, 2012). RNA processing is affected by m6A reader proteins; two kinds of m6A readers, YTHDF and YTHDC, can bind to the m6A sites in mRNA to implement the biological function of methylation modifications (Du et al, 2016; Patil et al, 2018; Scutenaire et al, 2018). It has become clear that this reversible posttranscriptional modification is indispensable for gene regulation

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