Phenotyping tan spot across mungbean cultivars for disease severity and pathogen load

Abstract

Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff) is a seed-borne pathogenic bacterium that causes tan spot of mungbean (Vigna radiata) and several members of the Fabaceae. Tan spot is a widespread but sporadic disease, capable of impacting mungbean yield under conducive environmental conditions. The genetic diversity and pathogenicity of a collection of Australian Cff isolates has recently been characterised, identifying a plasmid as a pathogenicity factor. Quantitative PCR (qPCR) tests were subsequently developed to allow detection and quantification of the pathogen using characteristic DNA markers. This study presents the reactions of major mungbean cultivars to tan spot disease using visual disease severity and pathogen load (as determined by qPCR) in controlled environment experiments. This information will support cultivar selection decisions for growers and highlights the responses of cultivars recently released through the National Mungbean Improvement Program.