Characterization and Detection of Bacterial Pathogens of Common Bean

Abstract

Common bacterial blight (CBB) (Xanthomonas axonopodis pv. phaseoli (Xap) and X. fuscans pv. fuscans (Xff), halo blight (Pseudomonas savastanoi pv. phaseolicola (Psp)), and bacterial brown spot (P. syringae pv. syringae (Pss)), are yield-limiting diseases of common bean in North Dakota and Minnesota. The objectives of this research were to optimize a multiplex quantitative PCR (qPCR) assay for rapid detection and quantification of four bacterial pathovars in common bean seed, leaf, and pod tissue; determine the aggressiveness of Xap and Xff isolates; and determine the race types of Psp isolates in North Dakota and Minnesota. A fourplex qPCR assay was optimized, and novel primers and probe were designed for pathovar-specific detection of Pss. Significant differences were observed in Xap/Xff aggressiveness across isolates evaluated and in susceptibility of the differential lines (P <.0001). The 60 Psp isolates were identified as Race 6, the predominant race in the region.