Effect of AUR1 gene intron on the expression of inositol phosphorylceramide synthase and pathogenicity in Botrytis cinerea

Abstract:

Abstract:［Objective］AUＲ1 encoding inositol phosphorylceramide (IPC) synthase is the key enzyme for the sphingolipid metabolism in fungi. In this study，we explored the mechanism of AUR1 intron on the regulation of AUR1 gene expression at transcriptional and translational levels in Botrytis cinerea，as well as the influence of AUR1 intron on the pathogenicity．［Methods］AUR1 mRNA expression of wild-type B．cinerea (BcAUR1 ) and the mutant with deletion of 115 bp intron (BcAUR1a) was detected by Real-time quantitative PCR．The activity of IPC synthase from BcAUR1 and BcAUR1a was measured through high-efficiency liquid fluorescent chromatogram．In addition，H2O2 concentration and activities of superoxide dismutase (SOD)，peroxidase (POD) and catalase (CAT) per unit fungus were determined by horseradish peroxidase，pyrogallol oxidation，guaiacol and ultraviolet spectrophotometric，respectively.［Results］IPC synthase had no amino acid mutation in mutant BcAUR1a．The expression of AUR1 gene at mRNA level and the activity of IPC synthase in BcAUR1a increased by 50.2% and 14.16% compared to those in BcAUR1．The secretion of H2O2，SOD，POD and CAT in BcAUR1 was significantly stimulated by Aureobasidin A (AbA) treatment，in contrast，no significant influence was detected upon the secretion of these substances in BcAUR1a via AbA treatment.［Conclusion］The expression of AUR1 in BcAUＲ1a is significantly up-regulated at transcriptional and translational levels．AbA treatment can significantly enhance the pathogenicity of BcAUR1，but has a minor influence on the BcAUR1a． BcAUR1a is AbA-resistant．The results suggest that AUR1 gene intron regulate the expression of AUR1 as a transcriptional repressor．