Transcriptome analysis of wild soybean (Glycine soja) in response to frogeye leaf spot caused by Cercospora sojina

Abstract

Frogeye leaf spot (FLS), caused by Cercospora sojina, is a threat to soybean cultivation, leading to substantial economic losses. Here, an RNA sequencing analysis was conducted to identify genes associated with the response of wild soybean (Glycine soja) to C. sojina. Differentially expressed genes (DEGs) were identified by comparing the gene expression of C. sojina-inoculated plants with that of non-inoculated plants. A total of 1642 DEGs (790 up-regulated and 852 down-regulated) were identified in C. sojina-inoculated wounded leaves compared with non-inoculated wounded leaves. The DEGs were analyzed for gene ontology and the KEGG pathway to identify the key genes responsible for the response to C. sojina and the corresponding pathways. In GO analysis, ‘Defense response’ was highlighted, while in KEGG analysis, ‘Metabolic pathways’ and ‘Flavonoid biosynthesis’ were emphasized. A total of 67 DEGs were categorized within the 'biotic stress' MapMan category, with ‘Redox state,’ ‘Cell wall,’ and ‘Secondary metabolites’ showing the highest abundance of assigned DEGs. DEGs associated with the phenylpropanoid pathway (GsALDH and GsAOMT-like), cell wall remodeling (GsPME12), and reactive oxygen species (GsGSTUs), were identified in plants inoculated with C. sojina compared to non-inoculated plants. Additionally, Gs2MF3OR-like (encodes an enone oxidoreductase) and Gsα-DOX1-like (involved in oxidative stress) also participated in the response of wild soybean to the disease. Our results suggest potential C. sojina-resistant genes that could serve as targets for further functional characterization, as well as for soybean molecular breeding programs aimed at improving FLS resistance.