Detection of Pseudomonas Syringae pv. Lachrymans Associated with the Seeds of Cucurbits

Abstract

Seed-borne bacteria that impair germination and emergence of seedlings and reduce yield and quality of cucurbits are of major concerns for cucurbit production throughout the world. The present investigation has been carried out to detect bacteria from the seeds of eight cucurbits viz. cucumber, bottle gourd, wax gourd, sweet gourd, ridge gourd, bitter gourd, sponge gourd and snake gourd collected from the different shops of Mymensingh town during July to November 2011. Seed samples were tested to detect seed-borne bacteria by nutrient agar plate method, cassette holder and liquid assay method. Only one bacterium was isolated and identified through nutrient agar plate and liquid assay method. The bacterium was identified as Pseudomonas syringae based on creamy white color colonies on the nutrient agar plate. The Pathogenicity test revealed that the bacterium was able to cause leaf spot symptom on the seedlings of all cucurbits confirming that the bacterium was Pseudomonas syringae pv. lachrymans. Hypersensitive response (HR) test on tobacco leaves caused partial death of local cell of tissues (HR) within the infiltrated area of tobacco leaves (cv. Bankete -A1). Gram staining and KOH test indicated the bacterium was gram negative and it was not able to grow at temperature 37 0 C and