Biocontrol of tomato bacterial wilt and biofilm formation by Bacillus subtilis strains GAPB2 and GAPB3

• Main Authors: Grimar A. Perez, 古晶格
• Other Authors: Tzu-Pi Huang
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/13644991421314561751

碩士 === 國立中興大學 === 國際農學碩士學位學程 === 104 === Plant growth-promoting rhizobacteria (PGPR) are microorganisms that can colonize plant roots and promote plant growth. Moreso, application of certain PGPR may suppress plant diseases. The goal of our study was to isolate strains of Bacillus subtilis from natural environments in Taiwan that show significant antagonistic activity against various plant pathogens including Ralstonia solanacearum PS152 and to evaluate the potential of isolated strains as biocontrol agents against tomato bacterial wilt. We screened a total of 123 isolates from various locations in Taichung county, Taiwan. Two strains, GAPB2 and GAPB3 isolated from rhizosphere soils at Taiping District, Taichung City showed significant antagonistic activity against R. solanacearum PS152. These wild strains tested positive for 2,3-butanediol, a known volatile for growth promotion, biofilm formation in defined medium as well as on tomato roots and leaves, and showed strong antagonistic activity against other plant pathogens including Fusarium oxysporum f. sp. niveum F182, Colletotrichum gloeosporioides GH-A, Phytophthora capsici PC213061, Xanthomonas axonopodis pv. citri XW19, and Xanthomonas euvesicatoria XPN37. Under greenhouse conditions these strains reduced disease incidence by 60-70% and 50-60% in infested soil containing 106 CFU per g and 107 CFU per g of R. solanacearum PS152, respectively. The strains were also able to promote plant growth as observed in a significantly higher shoot fresh mass, shoot dry mass, root fresh mass, root dry mass, number of nodes, plant height and stem diameter of tomato when compared to the control treatments. Results indicate that B. subtilis strains GAPB2 and GAPB3 provide promising biocontrol efficacy on tomato bacterial wilt as well as plant growth promoting activity. AtSWEET2 was shown to be important for B. subtilis strain GAPB2 root colonization, but not necessary for Arabidopsis leaf colonization.