Ethylene Production byPseudomonas syringaePathovars In Vitro and In Planta

identical levels of ethylene (about 5 310 27 nl h 21 cell 21 ), which were about 10 times higher than the ethylene level ofP. syringaepv. pisi. Two 22-bp oligonucleotide primers derived from the ethylene-forming enzyme (efe) gene of P. syringae pv. phaseolicola PK2 were investigated for their ability to detect ethylene-producing P. syringaestrainsbyPCRanalysis.PCRamplificationwiththisprimersetresultedinaspecific0.99-kbfragment in all ethylene-producing strains with the exception of theP. syringaepv. pisi strains. Therefore,P. syringaepv. pisi may use a different biosynthetic pathway for ethylene production or the sequence of the efe gene is less conserved in this bacterium.P. syringaepv. phaseolicola isolated from kudzu andP. syringaepv. glycinea also produced ethylene in planta. It could be shown that the enhanced ethylene production in diseased tissue was due to the production of ethylene by the inoculated bacteria. Ethylene production in vitro and in planta was strictly growth associated. Ethylene is a well-studied gaseous plant hormone. It is involved in the regulation of numerous physiological processes,