N6-methyladenosine (m6A) sequencing reveals Heterodera glycines-induced dynamic methylation promoting soybean defense

Unraveling the intricacies of soybean cyst nematode (Heterodera glycines) race 4 resistance and susceptibility in soybean breeding lines—11-452 (highly resistant) and Dongsheng1 (DS1, highly susceptible)—was the focal point of this study. Employing cutting-edge N6-methyladenosine (m6A)-seq and RNA-seq techniques, we delved into the impact of m6A modification on gene expression and plant defense responses. Through the evaluation of nematode development in both resistant and susceptible roots, a pivotal time point (3 days post inoculation) for m6A methylation sequencing was identified. Our sequencing data exhibited robust statistics, successful soybean genome mapping, and prevalent m6A peak distributions, primarily in 3'UTR (Untranslated region) and stop codon regions. Analysis of differentially expressed m6A peaks (DMPs) and expressed genes (DEGs) revealed distinctive patterns between resistant and susceptible genotypes. In the highly resistant line (11-452), key resistance and defense-associated genes displayed increased expression coupled with inhibited methylation, encompassing crucial players like R genes, receptor kinases, and transcription factors. Conversely, the highly susceptible DS1 line exhibited heightened expression correlated with decreased methylation in genes linked to susceptibility pathways, including Mildew Locus O (MLO)-like proteins and regulatory elements affecting defense mechanisms. Genome-wide assessments, GO/KEGG analyses, and DMP/DEG overlap emphasized the intricate interplay of m6A modifications, alternative splicing, microRNA and gene regulation in plant defense. Protein-protein interaction networks illuminated defense-pivotal genes, delineating divergent mechanisms in resistant and susceptible responses. This study sheds light on the dynamic correlation between methylation, splicing, and gene expression, providing profound insights into plant responses to nematode infection.