| Banana wilt is a serious soil disease, and seriously affected banana industry development. there were some relationship between soil microbial populations diversity and the happened of banana wilt. Bacillus subtilus stain R31 and TR21 were isolated by Zhuhai Modern for banana wilt PGPR, there were good result for control banana wilt by Bacillus subtilus stain R31 and TR21 through irrigated root or spray. For research the relationship between these two bacillus application and microbial in rhizoshpere, especially bacillus in rhizosphere, we collected different soil samples of irrigated root by R31 WP and sprayed TR21 WP of different dwarf banana phenotypes. For research the effect of cultivated microbial in different phenotypes rhizosphere by R31 WP irrigated root and TR21 WP sprayed, and the effect of bacillus and fusarium community, collect the number of bacteria, fungi, actinomycetes, bacillus and fusarium in healthy and illness plant rhizosphere,at the same time, identified the isolated bacillus and fusarium, analysis the component of two microbial. Through analysed bacillus component, dominate strain and biodiversity, reveal the connected of rhizospheric bacillus and banana wilt occurrence, for more explanation the control mechanism and provide theory for control banana wilt by R31 and TR21.The results showed that control efficiency of R31 on “red stem” phenotype was higher than “green stem” phenotype of Zhongfen NO.1, biocontrol effect on “green stem” phenotype of Zhongfen NO.1 was only 23.00%, while it on “red stem” phenotype reached 56.14%. Microbial counting results indicated that after R31 applying, the numbers of cultivable rhizosphere bacteria were increased, but the numbers of cultivable fungi, actinomycetes and fusarium were decreased. Though R31 have no notable influence on the number of rhizospheric bacillus of “red stem” phenotype of Zhongfen NO.1, but it could increase the number of rhizospheric bacillus of “green stem” phenotype conspicuous.The control efficiency of TR21 on “red stem” phenotype was 69.88%,and there was no statistics on “red stem” phenotype of Zhongfen NO.1.Microbial counting results indicated that after TR21 applying, the numbers of cultivable rhizospheric bacteria in “red stem” phenotype were remarkable decreased, but increase the numbers of cultivable rhizospheric bacteria in “green stem” phenotype remarkably, the numbers of cultivable rhizospheric fungi in “red stem” phenotype were remarkable increased, but decrease the numbers of cultivable rhizospheric fungi in “green stem” phenotype remarkably. TR21 applying could remarkable decrease number of actinomycetes in both phenotype of Zhongfen NO.1. TR21 applying could remarkable decrease number of fusarium in “red stem” phenotype rhizosphere and increase number of fusarium in “green stem” phenotype rhizosphere. TR21 applying had no notable influence on the number of bacillus in both phenotype of Zhongfen NO.1. Soaked in water decrease number of bacteria, fungi, actinmycetes and fusarium, but increase number of bacillus.Isolated 33 strain cultivated bacillus and identified them by gyr B gene. 29 strains could be identified to species. Beside there were 1 strain Paenibacillus sp, 2 strains Brevibacillus sp and 1 strains Bacillus sp. could not be identified to species. There were some bio-character different between the isolated bacillus.In order to research the function of the Bacillus strains in rhizosphere, the terms “important functional Bacillus”, “weak functional Bacillus”, “no functional Bacillus” and “negative functional Bacillus” were defined. The important functional Bacillus had broadly spectrum suppressive activity to Banana Fusarium Wilt pathogens, had diffusivity on plate and could interact with R31 released bio-film formation information. The weak functional Bacillus had broadly spectrum suppressive activity to Banana Fusarium Wilt pathogens, but had weak diffusivity on plate or weak interact with R31 released bio-film formation information. No functional Bacillus were strains which had no suppressive or very weak suppressive function on Banana Fusarium Wilt pathogen. Negative function Bacillus were strains which had no suppressive function on Banana Fusarium Wilt pathogen, but had strongly diffusivity on plate and could interact with R31 released bio-film formation message.The results by cluster and biodiversity analysis suggested that rhizospheric Bacillus community structure and diversity had been changed after R31 applying, biodiversity of “red-pesudostem” and “green-pesudostem” rhizospheric Bacillus had been decreased. The results of dominant species and functional Bacillus analysis showed that R31 applying changed the rhizospheric Bacillus structure through increasing rhizospheric important functional Bacillus species, balancing all kinds of important functional Bacillus colonization number in rhizosphere and decreasing no functional or negative functional Bacillus proportion. The result of cluster analysis and biodiversity analysis suggested that Bacillus community structure in rhizosphere had been changed and diversity of rhizospheric Bacillus increased after TR21 applying. The results of dominant species and function Bacillus analysis suggested that TR21 applying also change the rhizosphereic Bacillus structure mainly through increasing rhizospheric important functional Bacillus proportion in community and decreasing negative Bacillus proportion in community. In control area, the proportion and number of negative functional Bacillus in rhizosphere had more important relationship with plant healthy.R31 treated could reduce fusarium diversity in “red stem” phenotype rhizosphere but increase fusarium diversity in “green stem” phenotype rhizosphere of Zhongfen NO.1. TR21 treated also could reduce fusarium diversity in “red stem” phenotype rhizosphere but increase fusarium diversity in “green stem” phenotype rhizosphere of Zhongfen NO.1. The cluster analysis result of cultivated fusarium and PCR-DGGE suggest that R31 and TR21 applying had notable regulated to “red stem” phenotype Zhongfen NO.1 rhizospheric fusarium community structure but regulated to “green stem” phenotype Zhongfen NO.1 was not remarkable. The regulation to rhizospheric bacillus and fusarium of R31 and TR21 correlated to banana wilt control efficiency. |
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