Ethylene Production by the Kudzu Strains ofPseudomonas syringaepv.phaseolicolaCausing Halo Blight inPueraria lobata(Willd) Ohwi

摘要

Significant amounts of ethylene was produced byPseudomonas solanacearum(all strains),P. syringaepv.phaseolicola(Kudzu strains isolated fromPueraria lobata) andErwinia rhapontici(2 strains out of 22) out of 24 species, 3 subspecies and 38 pathovars of plant pathogenic bacteria tested in yeast extract-peptone broth. The bean strains ofP. syringaepv.phaseolicolacausing halo blight in kindney bean plants did not produce ethylene. The Kudzu strains produced ethylene at a rate of 7 to 100×10−9nl cell−1h−1, which was 500 to 1,000 times higher than that ofP. solanacearumand several times higher than that ofPenicillium digitatum, the most potent ethylene producer known among microorganisms.The presence of living cells was essential for ethylene production by the Kudzu strains. The bacterium effectively produced ethylene from amino acids such as glutamate, aspartate and their amides. Although glucose and succinate were also good substrates for ethylene biosynthesis, the rate of ethylene production was significantly smaller than that with glutamate. Methionine, which is known as the precursor of ethylene in plants, had no effect on ethylene production by the bacterium. 1-Aminocyclopropane-1-carboxylic acid (ACC) also had no effect on ethylene production, and there was not enough ACC in the bacterial cells to account for the high rate of ethylene production. Ethylene production from glutamate was inhibited byn-propylgallate and EDTA, but not by aminoethoxyvinylglycine. These results indicate that ACC is not involved as an intermediate in the process of ethylene biosynthesis by the bacterium, suggesting the presence of a pathway different from that of plant t