Species diversity of Pectobacterium spp. causing potato aerial stem rot in China.

Abstract

Pectobacterium spp. are the primary causative agents of aerial stem rot in potatoes in China. A nationwide survey revealed the widespread occurrence of aerial stem rot in the northern, southern, and southwestern cultivation regions, with occurrence rates ranging from 1% to 60%. In total, 36 strains were isolated and identified at the species level using multi-locus sequence analysis of six housekeeping genes (rpoS, proA, gapA, icdA, gyrA, and mdh). Genome sequencing was conducted on one representative strain for each species, and further confirmation of their identities was achieved through ANI and isDDH analysis. Five Pectobacterium species were identified, namely Pectobacterium atrosepticum, Pectobacterium brasiliense, Pectobacterium carotovorum, Pectobacterium polaris and Pectobacterium punjabense, with P. atrosepticum and P. brasiliense being the most widely distributed. Pathogenicity tests demonstrated that, among the strains isolated in this study and those obtained from other studies, P. atrosepticum and P. brasiliense are also the most virulent species. To the best of our knowledge, this is the first nationwide study describing the diversity and distribution of Pectobacterium spp. affecting potatoes in China. The information gathered will be utilized for disease diagnosis and the development of pathogen-specific integrated pest management (IPM) strategies to protect potato production.