Expression Analysis of the Expanded Cercosporin Gene Cluster in Cercospora beticola

Abstract

Cercospora leaf spot is an economically devastating disease of sugar beet caused by the fungus Cercospora beticola. It has been demonstrated recently that the C. beticola CTB cluster is larger than previously recognized and includes novel genes involved in cercosporin biosynthesis and a partial duplication of the CTB cluster. Several genes in the C. nicotianae CTB cluster are known to be regulated by ‘feedback’ transcriptional inhibition. Expression analysis was conducted in wild type (WT) and CTB mutant backgrounds to determine if feedback inhibition occurs in C. beticola. My research showed that the transcription factor CTB8 which regulates the CTB cluster expression in C. nicotianae also regulates gene expression in the C. beticola CTB cluster. Expression analysis has shown that feedback inhibition occurs within some of the expanded CTB cluster genes. The partial duplication of the CTB cluster was not found to be light activated or subject to feedback inhibition.