Biocontrol Effects Of Marine Bacteria SH27Associated With The Coral Against Phytophthora Sojae

Eleven bacteria which obtained from corals, seaweeds and mangroves showedantagonistic effect against Phytophthora sojae. Among them, the strain SH27associatedwith corals had the strongest antagonisms against experiment pathogen. So that, the strainSH27was used as the target strain in the paper.Based on morphology, physiological and biochemical property together with16SrDNA, gyrA, yyaO/yyaR sequences analysis, the strain SH27was identified as Bacillusamyloliquefaciens.Taking advantage of resistance to Rifampin and P.sojae to determine how long theSH27strain could colonize in the soybean seedlings. Results showed that: SH27couldcolonize31days in the soybean, but didn’t be isolated from the root by daubing leaves.Total amount of endogenous bacteria and endophytic culturable bacteria in different organsof soybeans were investigated by acridine orange fluorescence microscopy and tabletseparation, respectively. The results showed as follows: a large number of endophyticbacteria were distributed in different tissues, the average number of root, stem and leafwere7.16×107ind./g,3.98×107ind./g and4.16×107ind./g. In culturable bacteria aspect,the content of bacteria in different parts were16.36×105cfu/g,7.18×105cfu/g and6.43×105cfu/g, increasing88.91%,79.95%and97.24%comparing to CK, respectively.In soybean growth-promoting aspects, SH27fermentation broth had the most effect.Based on determination results of the height, fresh and dry weight, chlorophyll and rootactivity, the fermentation broth one process, two processes and three processes weresignificantly higher than the control treatment, increasing41.90%,53.63%and57.82%in chlorophyll content,87%,106.45%and180.64%in root activity. Using Li-6400theexperiment groups had determined the Photosynthesis rate, Transpiration, Efficiency ofwater application. They were increasing47.63%,67.6%and70.1%in photosynthesisrate,9.57%,31.1%and23.2%in transpiration,34.59%,27.57%and37.84%inefficiency of water application, respectively.The strain SH27was used to prevent P.sojae. The results showed that: the controlefficacy of individuals, liquid supernatant and fermentation broth were0.77%,30.00%,52.86%,9days after inoculation of the pathogen. In ninth day, the control efficacy of1.0×108,1.0×107,1.0×106cfu·mL-1SH27fermentation broth were52.86%,34.29%,23.33%. The seedlings watered roots with SH27fermentation broth and inoculated the pathogen at0,24,48and72h, in9th day the control efficacy were23.32%,41.29%,49.94%and52.44%, respectively. The prevention mechanism of the strain SH27controlling phytophthora blight showed that: compared with the treatment P.sojae, theSH27strain could reduce the contents of the soluble protein, MDA and activities of CAT,POD and SOD. PAL activity showed a different trend, co-inoculated with the strain SH27and P.sojae at the same time on the soybean seedlings has the most activity. Inducing PALactivity may enhance the anti-disease capability of plants.