[Objective] This study aimed to investigate the combined control effects of endophytic bacteria at different growth stages against cotton Verticfllium wilt and pro- vide a new strategy for the biocontrol of other soil...[Objective] This study aimed to investigate the combined control effects of endophytic bacteria at different growth stages against cotton Verticfllium wilt and pro- vide a new strategy for the biocontrol of other soil-borne diseases. [Method] Endophytic bacteria with high resistance against Verticillium wilt were isolated from seedling, squaring and boll-setting cotton vascular, respectively. Their 16S rDNA se- quences were detected for comparative analysis. Three biocontrol strains were se- lected and identified, whose colonization roles in cotton plants were explored. The control efficiency was determined with indoor and field experiments. [Result] Accord- ing to the 16S rDNA sequence homology, the three strains were identified as Paeni- bacillus polyrnyxa YUPP-8, Paenibacillus xylanilyticus YUPP-1 and Bacillus subtilis YUPP-2, respectively. Results of colonization assessment showed that three strains all could be successfully colonized in cotton vascular. However, application amount had a positive effect on the number of colonized biocontrol bacteria in cotton, strain YUPP-8 had the largest number of colonized biocontrol bacteria in seedling period, strain YUPP-1 had the largest number of colonized biocontrol bacteria in squaring period, and strain YUPP-2 had the largest number of colonized biocontrol bacteria in boll-setting period. Indoor pot experiment showed that cotton plants in combined bio- control bacteria treatment group were not infected in flowing period, while Verticillium wilt morbidity rate of cotton treated with single strain in seedling period were 6.7% （YUPP-8）, 6.7% （YUPP-1） and 13.3% （YUPP-2）; however, Verticillium wilt morbidity rate wilt of the control reached 80%. Field experiment conducted during 2010-2011 showed that the combined application of three strains had better effect than separate application; specifically, Verticillium wilt morbidity rate and disease index of cotton in boll-setting period with combined application of three strains in 2010 were 9.4% and 6.5, respectively, while those in control group were 47.5% and 32.8; results in 2011 were similar to 2010, with higher disease severity. These results indicate that com- bined application of endophytic bacteria at different growth stages has great applica- tion potential in control of cotton Verticillium wilt. [Conclusion] This study preliminarily overcomes the defects in the application of biocontrol bacteria and provided reference for the prevention and treatment of other soil-borne diseases.展开更多
Bacterial adhesion is crucial to the dissolution of minerals and rocks. By employing dialysis method, we designed comparative experiments to investigate the dissolution behavior of anorthite with the mediation of both...Bacterial adhesion is crucial to the dissolution of minerals and rocks. By employing dialysis method, we designed comparative experiments to investigate the dissolution behavior of anorthite with the mediation of both adhered and non-adhered Paenibacillus polymyxa. The results show that during 10 experimental days, the dissolution of anorthite was promoted considerably by P. polymyxa and metabolites. Nanoscale precipitates were formed in contact experiment. Anorthite has a higher release of Ca and lower releases of Al and Si in dialysis experiment than in contact experiment. The difference implies that the release of Ca is controlled by mechanism of proton-exchange, whereas those of A1 and Si are controlled by ligand-complexation in which A1-O-Si bonds are destroyed first. Kinetically the release of Ca is controlled mainly by surface reaction and leached-layer diffusion. Both of them are restrained by adhered bacteria. The releases of AI and Si are controlled mainly by surface reaction, which is accelerated by adhered bacteria.展开更多
Fusarium wilt is one of the most serious diseases of banana plants caused by soil-borne pathogen Fusarium oxysporum f.sp. cubense(FOC). In this study a pot experiment was conducted to evaluate the effects of different...Fusarium wilt is one of the most serious diseases of banana plants caused by soil-borne pathogen Fusarium oxysporum f.sp. cubense(FOC). In this study a pot experiment was conducted to evaluate the effects of different bio-organic fertilizers(BIOs) on Fusarium wilt of banana, including the investigations of disease incidence, chitinase and β-1,3-glucanase activities of banana plants, and FOC populations as well as soil rhizosphere microbial community. Five fertilization treatments were considered, including chemical fertilizer containing the same N, P and K concentrations as the BIO(control), and matured compost mixed with antagonists Paenibacillus polymyxa SQR-21 and Trichoderma harzianum T37(BIO1), Bacillus amyloliquefaciens N6(BIO2), Bacillus subtilis N11(BIO3), and the combination of N6 and N11(BIO4). The results indicated that the application of BIOs significantly decreased the incidence rate of Fusarium wilt by up to 80% compared with the control. BIOs also significantly promoted plant growth, and increased chitinase andβ-1,3-glucanase activities by 55%–65% and 17.3%–120.1%, respectively, in the banana roots. The population of FOC in the rhizosphere soil was decreased significantly to about 104 colony forming units g-1with treatment of BIOs. Serial dilution plating and denaturing gradient gel electrophoresis analysis revealed that the application of BIOs increased the densities of bacteria and actinomycetes but decreased the number of fungi in the rhizosphere soil. In general, the application of BIOs revealed a great potential for the control of Fusarium wilt disease of banana plants.展开更多
基金Supported by Public Welfare Industry(Agriculture)Research Special Project of Ministry of Agriculture(nyhyzx07-052)Open Project of the State Key Laboratory of Agricultural Microbiology(AML200806)+1 种基金Major Project of Hubei Provincial Department of Education(Z20091201)National College Students Innovative Experimental Program(091048922)~~
文摘[Objective] This study aimed to investigate the combined control effects of endophytic bacteria at different growth stages against cotton Verticfllium wilt and pro- vide a new strategy for the biocontrol of other soil-borne diseases. [Method] Endophytic bacteria with high resistance against Verticillium wilt were isolated from seedling, squaring and boll-setting cotton vascular, respectively. Their 16S rDNA se- quences were detected for comparative analysis. Three biocontrol strains were se- lected and identified, whose colonization roles in cotton plants were explored. The control efficiency was determined with indoor and field experiments. [Result] Accord- ing to the 16S rDNA sequence homology, the three strains were identified as Paeni- bacillus polyrnyxa YUPP-8, Paenibacillus xylanilyticus YUPP-1 and Bacillus subtilis YUPP-2, respectively. Results of colonization assessment showed that three strains all could be successfully colonized in cotton vascular. However, application amount had a positive effect on the number of colonized biocontrol bacteria in cotton, strain YUPP-8 had the largest number of colonized biocontrol bacteria in seedling period, strain YUPP-1 had the largest number of colonized biocontrol bacteria in squaring period, and strain YUPP-2 had the largest number of colonized biocontrol bacteria in boll-setting period. Indoor pot experiment showed that cotton plants in combined bio- control bacteria treatment group were not infected in flowing period, while Verticillium wilt morbidity rate of cotton treated with single strain in seedling period were 6.7% （YUPP-8）, 6.7% （YUPP-1） and 13.3% （YUPP-2）; however, Verticillium wilt morbidity rate wilt of the control reached 80%. Field experiment conducted during 2010-2011 showed that the combined application of three strains had better effect than separate application; specifically, Verticillium wilt morbidity rate and disease index of cotton in boll-setting period with combined application of three strains in 2010 were 9.4% and 6.5, respectively, while those in control group were 47.5% and 32.8; results in 2011 were similar to 2010, with higher disease severity. These results indicate that com- bined application of endophytic bacteria at different growth stages has great applica- tion potential in control of cotton Verticillium wilt. [Conclusion] This study preliminarily overcomes the defects in the application of biocontrol bacteria and provided reference for the prevention and treatment of other soil-borne diseases.
基金supported by National Basic Research Program of China (Grant No. 2007CB815603)National Natural Science Foundation of China (Grant No. 40802015)Ph. D. Programs Foundation of Ministry of Education of China (Grant Nos. 20050284043,20050284044)
文摘Bacterial adhesion is crucial to the dissolution of minerals and rocks. By employing dialysis method, we designed comparative experiments to investigate the dissolution behavior of anorthite with the mediation of both adhered and non-adhered Paenibacillus polymyxa. The results show that during 10 experimental days, the dissolution of anorthite was promoted considerably by P. polymyxa and metabolites. Nanoscale precipitates were formed in contact experiment. Anorthite has a higher release of Ca and lower releases of Al and Si in dialysis experiment than in contact experiment. The difference implies that the release of Ca is controlled by mechanism of proton-exchange, whereas those of A1 and Si are controlled by ligand-complexation in which A1-O-Si bonds are destroyed first. Kinetically the release of Ca is controlled mainly by surface reaction and leached-layer diffusion. Both of them are restrained by adhered bacteria. The releases of AI and Si are controlled mainly by surface reaction, which is accelerated by adhered bacteria.
基金Supported by the National High Technology Research and Development Program(863 Program)of China(No.2010AA10Z401)
文摘Fusarium wilt is one of the most serious diseases of banana plants caused by soil-borne pathogen Fusarium oxysporum f.sp. cubense(FOC). In this study a pot experiment was conducted to evaluate the effects of different bio-organic fertilizers(BIOs) on Fusarium wilt of banana, including the investigations of disease incidence, chitinase and β-1,3-glucanase activities of banana plants, and FOC populations as well as soil rhizosphere microbial community. Five fertilization treatments were considered, including chemical fertilizer containing the same N, P and K concentrations as the BIO(control), and matured compost mixed with antagonists Paenibacillus polymyxa SQR-21 and Trichoderma harzianum T37(BIO1), Bacillus amyloliquefaciens N6(BIO2), Bacillus subtilis N11(BIO3), and the combination of N6 and N11(BIO4). The results indicated that the application of BIOs significantly decreased the incidence rate of Fusarium wilt by up to 80% compared with the control. BIOs also significantly promoted plant growth, and increased chitinase andβ-1,3-glucanase activities by 55%–65% and 17.3%–120.1%, respectively, in the banana roots. The population of FOC in the rhizosphere soil was decreased significantly to about 104 colony forming units g-1with treatment of BIOs. Serial dilution plating and denaturing gradient gel electrophoresis analysis revealed that the application of BIOs increased the densities of bacteria and actinomycetes but decreased the number of fungi in the rhizosphere soil. In general, the application of BIOs revealed a great potential for the control of Fusarium wilt disease of banana plants.
