Pseudomonas savastanoi pv. glycinea affecting a vegetable soybean for commercial edamame production in Serbia

Abstract

The vegetable soybean “edamame” (Glicine max L.) is a nutritious legume having pods and seeds that can be harvested and consumed while they are still fresh and premature. Edamame is rich in micronutrients and vitamins and is therefore used as food and for medicinal purposes. In Serbia, edamame production started for the first time in 2019 on a 10 ha field in Bečej locality (Bačka, Vojvodina). Later, in 2021, its production was expanded to 30 ha, but in summer was followed with symptoms of bacterial leaf spot. The symptoms appeared on leaves in the form of water-soaked spots surrounded by a chlorotic halo that enlarged and coalesced into necrotic lesions. Disease incidence was from 15-20%. Isolation of the causal pathogen was performed by sowing of suspension of the macerated margins of spots/lesions from ten collected symptomatic leaves on nutrient agar supplemented with 5% sucrose. Ten representative, purified isolates were whitish, circular, smooth, shiny, levan-positive, strictly aerobic, gram-negative; positive for green-fluorescent pigment and tobacco hypersensitive response, and negative for oxidase, arginine dihydrolase, and potato soft rot (LOPAT group Ia). Pathogenicity of the isolates was confirmed on soybean cotyledons by under pressure atomizing a bacterial suspension (107-8 CFU mL 1 ). Sequencing of genes gapA, gyrB, and rpoD showed 100% homology of the obtained isolates with Pseudomonas savastanoi pv. glycinea pathotype strain LMG 5066 and strains BR1, KN166, KN28, KN44, LN10, MOC601, R4a (gapA and gyrB), and M301765 (gapA and rpoD) originated from soybean, all from the Plant Associated and Environmental Microbes Database (PAMDB).