Transcriptome analysis reveals putative pathogenesis genes in Alternaria panax during infecting Panax notoginseng leaves.

Background: Alternaria panax is the causative agent of black spot disease in Panax notoginseng, which causes significant yield loss. However, the molecular mechanisms underlying its pathogenicity remain mostly unknown.

Objective: We sequenced the transcriptome of A. panax during infecting P. notoginseng leaves using next-generation RNA-seq to understand the molecular aspects of black spot disease.

Methods: In this study, we sequenced the A. panax transcriptome during infecting P. notoginseng leaves through next-generation sequencing to explore the pathogenesis genes that may be responsible for black spot disease on P. notoginseng.

Result: The de novo transcriptome assembly of A. panax produced 23,036 unigenes, of which 18,096 genes were functionally annotated by at least one protein database. GO enrichment analysis and KEGG pathways of differentially up-regulated genes suggest that most genes are associated with metabolic processes, catalytic activity, starch, and sucrose metabolism during infection. Many pathogenesis-associated genes, including genes encoding secreted proteins, candidate secreted effectors, cell wall degrading enzymes, transcription factors, and transporters, were up-regulated in A. panax during infection. In addition, the secondary metabolite biosynthesis genes, including cytochrome P450, and nonribosomal peptide synthetases, were also identified in this study.

Conclusions: Differential gene expression analysis has confirmed that A. panax infection was mainly present in the middle and final stages. The findings show that these pathogenesis-associated genes in A. panax may be critical for the P. notoginseng black spots disease.