| Banana wilt disease, also known as the Panama disease or yellow leaf disease, is a kind of soil-borne disease caused by Fusarium oxysporum. fsp. Cubense FOC infecting the banana plant vascular tissue, leading to a devastating vascular necrosis rotten. It has been considered as a serious threat to banana industry of the world. Due to lack of effective resistance varieties and chemicals, safe, effective and environmental friendly biological control becomes the most potential method. Endogenous actinomyces in banana is one important part of the micro ecological environment and has played an important role in banana plant growth and development as well as resistance to pests and diseases. This research adopts the microbiology and plant physiology research methods, screening and identification of the endogenous antagonism of defense bacteria in the leaf and soil from different areas of health and disease of banana and the determination of colonization ability, analyzed the inhibitory action of prevention and control as well as the determination of plant induced resistance. Results are as follows.1. We collected3healthy and Furarium oxysporum f. sp infected banana samples from Lingao and Huangtong in Hainan province. After surface disinfection,142endophytic actinomycetes strains were isolated by means of tissue homogenates method. Using Furarium oxysporum f.sp cubense race4as target strain,6antagonistic actinomycete strains were screened by plate confrontation tests. Among them, Strain NJQG-3A1has the strongest inhibitory effects on mycelia growth and spore germination to FOC4. The inhibition rates can reach83.3%and100%, respectively. By cultivating character and bacteria morphology observationã€physiological and biochemical testã€16SrDNA sequencing, NJQG-3A1strain was identified as Streptomyces phaeoluteichromatogennes.2. Determination of broad spectrum antimicrobial properties of NJQG-3A1by using the tablet confrontation and drug-containing medium activity, the results show that the NJQG-3A1showed inhibition effects on Curvularia lunata, Curvularia fallax, Corynespora cassiicola (Berk&Curt) Wei, Fusarium oxysporum f. sp. Cubense No.1, Fusarium.sp. Deightoniella troulosa, etc. Especially for Curvularia lunata, bacteriostatic rate can reach88.33%.2. Determination of broad spectrum antimicrobial properties of NJQG-3A1by using the tablet confrontation and drug-containing medium activity, the results show that the NJQG-3A1showed inhibition effects on Curvularia lunata, Curvularia fallax, Corynespora cassiicola (Berk&Curt) Wei, Fusarium oxysporum f. sp. Cubense No.1, Fusarium.sp. Deightoniella troulosa, etc. Especially for Curvularia lunata, bacteriostatic rate can reach88.33%.3. The strain of NJQG-3A1was marked by antibiotics and it exhibits stable resistance. Pot experiment showed that the strain can colonize in the soil and the colonization can reach to104cfu/g soil; It can also colonize in banana plant within a certain time, and the colonization is102-103cfu/g tissue. The tissue measured quantity of living bacterium: root> bulb> stem> leaf.4. The control effects of the different concentrations of fermentation fluid with stain NJQG-3A1on banana wilt disease show that50times diluted fermentation fluid have the best control effect, the control efficiency of leaf and root-stems reached81.82%and88.98%, respectively; its role in the growth is most obvious:the processing of banana plants under the average plant height, stem circumference, fresh weight were2.00,1.47,3.31times that of the other controls, respectively; at the same time, five kinds of enzyme activity are higher than that of the other controls. Combined with the control effect results, suggesting that induced resistance may be one resistance mechanism of antagonistic bacterium fermentation liquid on control of banana fusarium wilt disease.This study provides high-quality strains for banana wilt disease biological control, and lay a theoretical foundation for the development and application of the strain. |
