Survival niches of Pseudomonas savastanoi pv. glycinea, causal agent of bacterial blight in soybean (Glycine max L.)

Abstract

Bacterial blight caused by Pseudomonas savastanoi pv. glycinea (Psg) is a prevalent disease in soybean crops worldwide, and crop rotation is a potential management strategy. However, the importance of alternative crops and soil as hosts of Psg is not well understood. This study aimed to assess the survival of Psg in four soil types, the phyllosphere, and rhizosphere of 12 crops rotated with soybean, and endophytic colonization of crops by Psg. The pathogenic strain Soj. 1462 of Psg, resistant to rifampicin, was used in all experiments, and culturing followed by PCR confirmed bacterial survival. Psg survived for a maximum of two days in all soil types. In both survival niches, phyllosphere and rhizosphere, sunn hemp, common bean, and turnip proved to be the crops with a shorter Psg survival period, lasting less than 28 days, while the remaining evaluated crops exhibited longer survival periods. In endophytic colonization, Psg survived for less than 35 days in these crops when inoculated in artificially wounded plants. When inoculated by spray in the same crops, the highest Psg survival was recorded up to 28 days. To reduce Psg inoculum, it is advisable to cultivate sunn hemp, common bean, and turnip in succession with soybean, given their comparatively lower recorded survival periods.