Identification and Pathogenicity of Phytopathogenic Bacteria associated with soft rot disease on some Potato Cultivars

摘要

Pathogenicity of potato soft rot and blackleg caused by Pectobacterium, Dickeya and Enterobacter pathogens were investigated in this study. Twenty three soft rot bacterial isolates were obtained from different locations of North West of Egypt Pathogenicity assessment was resulted in rotting on potato slices with tested isolates. Also pathogenicity was performed on seedling (Cara, Spunta and Ladybalfor cvs), showed tubers soft rot followed by leaves chlorosis and wilting as well as blackleg. Identification based on morphological, differential media, physiological and biochemical characteristics were proved that tested isolates belonging to Pectobacterium (Pec), Dickeya and Enterobacter. Disease severity was estimated as percentage to express disease index of rotted tissue weight of tubers (cv.Cara, Agria, Bern, Diamont, Ladybalfor and Valor). Results indicated that Pec isolates AS1 and AC5 were the most aggressive isolates and with highest percentage 26.21%, 23.34% respectively of infection, while PecKM15 isolate exhibited weak infection (18.17%). Whereas, no significant differences were found among isolates of Dickeya sp. in disease index. Potato cultivar Agria was the most sensitive versus Cara cv. was the most resistant to Enterobacter (KM23) isolate. Overall, Cara cultivar was more resistant to the infection by all tested isolates than other tested cultivars. On the other hand Valor and Ladypalfor cvs. were more susceptible of tested soft rot bacterial isolates.