Revealing the early pathogenic mechanisms of Agroatehlia rolfsii in Arachis hypogaea through RNA-seq and identification of ArNIS1-like effectors

BACKGROUND: Agroathelia rolfsii is a destructive soil-borne fungal pathogen, causing stem rot and huge economic losses in cultivated peanuts. The genome of ZY2, a highly pathogenic A. rolfsii strain, has been sequenced; however, there is still a lack of gene expression profiling during A. rolfsii infection of peanut. This study identified the key pathogenicity genes at the early stage of A. rolfsii infection through RNA-Seq analysis. RESULTS: After inoculation on peanut stems, a total of 1,222, 696, and 753 genes in A. rolfsii were upregulated at 1, 3, and 6 h post-inoculation, respectively. Gene ontology enrichment analysis revealed involvement of most of these genes in binding, oxidoreductase, and transporter activity, as well as enrichment of genes with hydrolase, ATP-dependent, transferase, and transcription regulator activities. Functional classification and analysis of these upregulated genes highlighted the potential importance of laccase, oxalic acid, effector, and transporter protein in the early infection of A. rolfsii. Transcriptome analysis and Agrobacterium-mediated transient expression first identified the necrosis-inducing secreted protein 1 (ArNIS1-like) effector in A. rolfsii. CONCLUSIONS: This study presented the first global transcriptome analysis of A. rolfsii during its early infection of peanut, and revealed the key roles of laccase, oxalic acid, effector, and transporter protein in suppressing peanut defense against A. rolfsii. The findings improve our understanding of the pathogenic mechanisms of A. rolfsii and its molecular interactions with peanut.