Bacterial rot of Chinese yam caused by Pseudomonas allii

Tuber rot is a major problem for the commercialization of the under-utilized Chinese yam ( Dioscorea polystachya ‘Nagaimo’), a tuber rich in nutrients and bioactive, health-promoting metabolites. Black to dark brown discoloration or indistinct lesions form on the surface of the tubers, and the discoloration spreads to internal tissues. Pseudomonas -like bacteria were isolated from lesions, caused the same symptoms in tubers after inoculation, and were identified as Pseudomonas allii based on phenotypic characteristics and phylogenetic features. This is the first report of bacterial rot caused by P. allii in Chinese yam.