The Influence Of DNA Methylation On Alternative Splicing In Rice Leaves Infected By Magnaporthe Oryzae

As one of the most important food crops in the world,rice(Oryza sativa)affects more than 50% of the world’s population.However,in many rice-growing areas of the world,rice production is seriously affected by a variety of diseases,the most important of which is the rice blast caused by Magnaporthe oryzae.According to statistics,the average annual rice production loss due to rice blast infection is up to 10-30%,or even no grain harvest.At the same time,traditional methods such as using fungicide cannot effectively reduce the yield loss caused by rice blast infection.Therefore,it is very important for rice production to study the pathogenic mechanism of rice blast infection and develop durable and effective resistant varieties.In recent years,more and more studies have shown that epigenetic modification,especially DNA methylation modification,plays an important role in plant response to pathogen infection.DNA methylation modification is conserved in eukaryotes and plays an important role in regulating gene expression and inhibiting transposon activity.In addition,DNA methylation also plays an important role in regulating transcriptional processes,such as Alternative splicing.Alternative splicing is known to play a role by regulating gene expression in plants in response to both biotic and abiotic stress.Therefore,this study hopes to study the dynamic changes of DNA methylation and its effect on alternative splicing in rice during rice blast infection,as well as the disease-resistance process of pathogen stress response genes co-regulated by them.This study performed genome-wide DNA methylation sequencing and transcriptome sequencing on rice leaves inoculated with Magnaporthe oryzae at different stages(0 day,1day,3days and 5 days),which is aimed at analyzing the relationship between DNA methylation dynamic changes and alternative splicing,revealing the dynamic changes of the gene expression network in response to rice blast infection,focusing on pathogen response genes and a variety of stress response genes.The results showed that:(1)more than 39% of multiexonic genes underwent alernative splicing after the fungal pathogen Magnaporthe oryzae infection.Among all kinds of identified alternative splicing events,intron retention(IR)is the most important form of alternative splicing,accounting for more than 40% of all alternative splicing events;(2)CG sequence context in gene body was positively correlated with gene expression,while CHG and CHH sequence contexts were negatively correlated with gene expression.Furthermore,consistent with previous studies in other plants,methylation level was the highest in the CG sequence context for genes with medium to high expression level in gene body;(3)DNA methylation in the three sequence contexts can affect alternative splicing in both positive and negative directions,that is,DNA methylation in the three sequence contexts can not only promote the occurrence of alternavtie splicing,but also inhibit the occurrence alternavtie plicing.At the same time,this study also found that DNA methylation in the three sequence contexts can only affect the splicing of part of alternative exons.In summary,this study provides theoretical and technical support for how DNA methylation is involved in the influence of alternative splicing and the expression and regulation of related biological pathway genes in rice in response to the biological stress of rice blast infection.It also provides a new perspective of epigenetic modification for the cultivation of resistant rice varieties and an important reference for the research on epigenetic modification of other crops.