IDENTIFICATION OF ERWINIA-CAROTOVORA FROM SOFT-ROT DISEASED PLANTS BYRANDOM AMPLIFIED POLYMORPHIC DNA (RAPD) ANALYSIS

Erwinia carotovora and pectolytic pseudomonads are the most prevalent bacteria associated with soft rot of plants. A procedure based on rand om amplified polymorphic DNA (RAPD) analysis was developed to distingu ish these bacteria rapidly and easily. Forty bacterial strains isolate d from diseased plants in the province of Quebec were used to screen R APD primers. Two primers were chosen based on cost considerations and on their capacity to discriminate between the bacterial strains. The c ombination of the two primers was sufficient for adequate distinction of Erwinia carotovora from pectolytic, fluorescent Pseudomonas spp. Fu rthermore, E. carotovora subsps. atroseptica and carotovora could also be distinguished from each other. To simplify the identification work , a quantitative identification tool was elaborated, based on selected markers produced with the two primers. To verify the RAPD analysis ac curacy, 49 additional soft rot bacteria from diseased plants were subm itted to the RAPD procedure and all the identifications were in agreem ent with those produced by standard biochemical tests. In addition, th e RAPD analysis correctly identified 25 bacteria from collections outs ide of Quebec.