Studies On Endophytic Microbe From Musa Genus Plants

Musa genus involved many species of important ornamental plants or fruit trees in southern China. Fusarium wilt disease of banana was a destructive soil-borne disease. Due to the difficulty of preventing and controlling the disease, more attention had been paid on the biocontrol in many countries. As a new kind of microbial resource, the endophytic microbe show great attraction to researchers. There were a lot of advantages to find some endophyte used as antagonistic bacteria for Fusarium wilt disease of banana, while compared to other biocontrol factors concerned. Therefore, the possibility of using some endophyte existing in healthy banana plants and being in resistance to Fusarium wilt disease of banana was investigated. First, endophytic microbe in four species of Musa genus plants from different areas were isolated and identified by fatty-acid analysis in this study. Then the quantity distribution of endophytic bacteria species was studied. At the same time, endophyte bacteria from Musa genus plants were screened for inhibiting four kinds of pathogens. And then, an antagonistic bacterium was screened for Fusarium wilt disease of banana. Further, the antagonistic bacterium was inoculated into banana seedlings, and its colonization was also studied. The main results are as follows:1. Isolation and quantity distribution of endophytic bacteria from Musa genus plantsThe results of statistical analysis showed that a great difference was found in the amount of endophytic bacteria among different species of Musa genus plants. The amount of endophytic bacteria in wild banana was the highest, and those in Musa uranoscopos and Musa basjoo were lowest. The amount of endophytic bacteria in the roots of Musa basjoo and'Williams'banana were much higher than that in the leaves and the stems. The amount of endophytic bacteria in the wild banana's leaves was higher than that in the roots. Those endophytic bacteria were gathered in multi-conduit systems. This study was conducted on different organs with the sort descending orders as follows: the mesophyll, the leaf, the petiole, the stem at the top, the central stem, the basal stem and root. Then, it was found that endophytic bacteria were not distributed in each organization of various parts.2. Identification and distribution of endophytic bacteria species from Musa genus plantsSalmonella spp., Pseudomonas spp., Enterobacter spp., Rhizobium spp., Bacillus spp., Klebsiella spp. and other 16 genera of endophytic bacteria were isolated, and 14 strains were identified to species'level. Salmonella spp., Klebsiella spp. and Pseudomonas spp. existed in different species of Musa genus plants and different plant organs. At the same time, they dominated in those plants. The distribution of the 14 bacterial species showed that there were differences in the amount distribution of different species of endophytic bacteria.3. Screening of antagonistic bacteria from Musa genus plants for several pathogensSixty-five endophytic bacteria from Musa genus plants were screened for antagonists against Ralstonia solanacearum, Fusarium oxysporum f. sp. Cubense, Colletotrichum orbiculared and Escherichia coli through the confrontation on the test plate. Pseudomonas aeruginosa H4-3-1 could inhibit three kinds of pathogenic bacteria in vitro for better results.4. Colonization of antagonistic bacteria, Pseudomonas aeruginosa H4-3-1, in banana seedlingsThe colonization of H4-3-1 anti-rifampicin mutant on banana's seedlings in the sand bed showed that, the lethal concentration of H4-3-1 was 107 to sand-bed banana seedlings after 7 days or 14 days. H4-3-1 strain was diluted with 10000 times and inoculated into 20-days tissue culture banana seedlings. The results showed that the bacterium could also colonize well in the seedlings after 20 days and the amount was still on a high level in the roots and stems, while the concentration of the endophytic bacteria was lower and the mortality rate of banana seedlings was small relatively.