Detection and characterization of Aspergillus tubingensis causing leaf rot disease in pak choi in China

Abstract

Pak choi (Brassica rapa ssp. chinensis) is China’s most common and important vegetable crop. In 2019, a devastating leaf rot disease was observed to be associated with pak choi plants, but no details on the cause of the disease were known. The aim of this study was to identify the agent causing pak choi leaf rot disease. Following Koch’s postulates, the causal agent was isolated from infected leaves and its pathogenicity confirmed by inoculation studies. The pathogen was classified as Aspergillus tubingensis based on its morphological characteristics. For molecular characterization, the β-tubulin gene, calmodulin (CaM) gene and internal transcribed spacer (ITS) region were sequenced and phylogenetic analyses were carried out. BLAST analysis of the sequenced genes showed 99% sequence identity to A. tubingensis with cognate sequences from the GenBank database. This is the first report of A. tubingensis causing leaf rot on pak choi in China.