Identification of Clt‐1‐Regulated Proteins Associated with the Production of Non‐Host‐Specific Toxin and Pathogenicity in Cochliobolus lunatus

Abstract

AbstractThe Curvularia leaf spot is caused by Curvularia lunata (telemorph: Cochliobolus lunatus), which produces a non‐host‐specific toxin known as methyl 5‐(hydroxymethyl) furan‐2‐carboxylate (M5HF2C). The Clt‐1 gene, which is from a pathogen closely associated with M5HF2C production and pathogenicity, was successfully cloned. However, the proteins related to toxin production or pathogenicity were not identified. In this study, a proteomic approach based on two‐dimensional gel electrophoresis (2‐DE) and mass spectrometry (MS) techniques was used to identify the specific proteins associated with Clt‐1 expression in C. lunatus wild‐type CX‐3 and Clt‐1 deletion mutant ΔClt‐1. Five upregulated and two downregulated proteins were identified in ΔClt‐1. Succinate dehydrogenase flavoprotein subunit (Sdh1p) functions as a coenzyme of dehydrogenase in the anabolism of toxin. Eukaryotic elongation factor 3 (EF‐3) facilitates the synthesis of important proteins required for the production of toxins in C. lunatus. Melanin synthesis‐related protein scytalone dehydratase (SCD) and stress tolerance‐related proteins (HSP30 and HSP70) contribute to the pathogenicity of C. lunatus. Real‐time quantitative PCR (RT‐qPCR) analysis showed that the Scd gene exhibited similar expression pattern at the transcriptional level, corresponding to the protein detected by 2‐DE. Bioinformatics analysis showed that Scd encodes a scytalone dehydratase subunit of 188 amino acids, which is clustered into one branch with dothideomycete SCD homologs in a phylogenetic tree. Further study on the exact role of the Scd gene is underway.