ISOLATION AND CHARACTERIZATION OF SEEDBORNE PSEUDOMONAS SYRINGAE PV PISI FROM PEA (PISUM SATIVUM L.)

Abstract

This study was focused on isolation and biochemical characterization of pea (Pisum sativum L.) seed borne bacteria.  A total of 25 bacteria were isolated from pea seeds collected from different sources.  Of 25 isolates, 3 most aggressive isolates (Psp-1, Psp-6, Psp-14) which produced hypersensitive response (HR) within 24 hours of post inoculation on tobacco leaf were picked for further bio-pathological assays. Bacterial isolates were able to produce brown necrotic spots on pea leaves after few days of inoculation which later coalesced and gave peculiar blight like appearance. However, bacterial isolates were unable to reduce nitrogen and also unable to grow at 41 ⁰C which considered as a hall mark of only plant pathogenic pseudomonads. Furthermore, results of LOPAT (levan production from sucrose (L), presence of oxidase (O), pectolytic activity on potato (P), the pres­ence of arginine dihydrolase (A) confirmed that seed borne bacteria were Pseudomonas syringae pv pisi which are reported as looming threat to pea production in different parts of world. Therefore, current study gave a clue about the presence of potential bacterial pathogens in seeds which would easily be resulted into future disease outbreak. Thus, regular disease surveillance and pathogenicity assays on commercial pea varieties must be incorporated to avoid any future pea epidemic.