Effect of volatile compounds produced by bacterial biocontrol agent Pseudomonas chlororaphis strain PA23 and its transposon mutants against Sclerotinia sclerotiorum
Pseudomonas chlororaphis strain PA23 has been found to produce three main volatile compounds, (nonanal, benzothiazole,2-ethyl-1-hexanol), which have inhibited mycelial, sclerotial and ascospore germination of Sclerotinia sclerotiorum. This study was initiated to understand whether phenazine biosynthetic genes or specific regulatory genes would have a negative or positive effect on the production of these compounds. Tn mutants of PA23 including PA23-63 (phzE-deficient), PA23-754 (phzC-deficient), PA23-314 (gacS-deficient), PA23-314 (gacS) (gacS complemented strain), PA23-443 (ptrA; transcriptional regulatory mutant) and PA23-443 (ptrA complemented strain) were tested for production of volatile compounds and their ability to inhibit the mycelial growth, sclerotial germination and ascospore germination of S. sclerotiorum. PA23, PA23-314, PA23-314(gacS), PA23-63, PA23-754 and PA23-443 (ptrA) showed a significant reduction (P=0.05) of mycelial growth and sclerotial germination ofS. sclerotiorum compared to PA23-314, PA23-443 and control. Strain PA23-754 (phzC mutant) exhibited the best inhibition of mycelial growth and sclerotial gennination, 25.56％ and 98.73％, respectively, followed by PA23-63 (phzE mutant),13.33％ and 84.84％. Except for PA23-314, all other strains were able to inhibit ascospore germination completely after 48 h. The results highlight the fact that the gacS regulatory gene plays a major role in PA23 antibiotic production. Furthermore, the phenazine-deficient mutants PA23-63 and PA23-754, showed enbanced antibiosis, which has been previously observed for production of organic non-volatile compounds. Volatiles produced by each nutant were collected for 120 h in a nutrient rich medium (Tryptic Soy Broth) and in a minimal medium (M9) to investigate whether the production of volatiles is medium dependant. All strains produced the compounds nonanal, benzothiazole, 2-ethyl-l-hexanol regardless of the medium used. We hypothesize that the relative intensity of these compounds may have an effect on the level and rate of inhibition. Our findings do not resolve the exact mechanism underlying regulation of organic volatile production in PA23; comsequently, additional studies are underway to elucidate their control.
Pseudomonas chlororaphis (PA23) Sclerotinia sclerotiorum Tn mutants antimicrobial organic volatiles GC MS
S.N.P.Athukorala W.G.Dilantha Fernando T.de Kievit K.Y.Rashid
Department of Plant Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada Department of Microbiology, University of Manitoba Winnipeg, MB R3T 2N2, Canada Cereal Research Centre, Agriculture and Agri-Food Canada, Morden Research Station, Morden, MB R6M 1Y
国际会议
第十二届国际油菜大会( The 12th International Rapeseed Congress)
武汉
英文
1441-1443
2007-03-26（万方平台首次上网日期，不代表论文的发表时间）