DETECTION OF NEW ETHYLENE-PRODUCING BACTERIA, PSEUDOMONAS-SYRINGAE PVS. CANNABINA AND SESAMI, BY PCR AMPLIFICATION OF GENES FOR THE ETHYLENE-FORMING ENZYME

Strains of Pseudomonas syringae (78 strains and 43 pathovars) and othe r strains (79) of plant and insect origin were examined for the presen ce of the ethylene-forming enzyme gene (efe) by polymerase chain react ion (PCR) assay. The sequence of the efe gene of P. syringae pv. phase olicola PK2 was used to design two primer sets for amplification of th e gene. In addition to P. syringae pv, phaseolicola (the ''kudzu strai n'') and P, syringae pv, glycinea, which were efficient ethylene produ cers, several strains of P. syringae pvs. sesami and cannabina generat ed PCR products of the predicted size. A DNA probe of the efe gene, is olated from strain PK2, hybridized to these PCR products, indicating h omology to the P, syringae pv. phaseolicola Efe gene. PCR restriction fragment length polymorphism analyses suggested that these four pathov ars harbor a similar efe gene. Furthermore, the probe hybridized to an indigenous plasmid of P. syringae pv. cannabina, suggesting that the efe gene could be located on a plasmid in this pathovar, but did not h ybridize to plasmids of P. syringae pv, sesami strains. P. syringae pv s. sesami and cannabina strains produced ethylene in King's medium B a t levels similar to those of P, syringae pvs. phaseolicola and glycine a. Thus, two new ethylene-producing bacteria were detected by the PCR assay.