Isolation,Screening,Identification Of Antagonistic Bacillus Against Wilt Disease Of Bambusa Pervariabilis×Dendrocalampsis Daii And It's Bio Control Effect

In recent years,with the widespread cultivation in the southwest region of China,Bambusa,Pervariabilis×Dendrocalampsisdaiihas become one of the most important economic timber stands and plays a significant role in the development of the bamboo.At the same time,BambusaPervariabilis×Dendrocalampsisdaii is also facing a variety of pest infestations particularly the hybrid bamboo blight caused by Fusarium oxysporum,which has caused large area of death and seriously hindered the development of the hybrid bamboo industry.Bacillus subtilis is widely distributed in nature,it can produce spores with strong resistance,and it requires simple nutrition,grows rapidly,produces a variety of metabolites,rhizosphere colonize easily,so it has been widely researched and used in the biological control of plant diseases.In order to obtain a set of compound Bacillus preparation with high efficiency and stable antagonistic effect.In this study,we collected soil samples from different areas,screened bacillus of antagonistic effect on Bambusa pervaria bilis Fusarium Wilt,and did classification and identification the genus of Antagonistic Bacteria's,then compound two strains of antagonists which were of obvious antagonism and good affinity,followed by exploring the bio control effect of single strain and mixed strains and studying the resistance physiology influence of the hybrid Bamboo after inoculating.In this experiment,179 strains of Bacillus were isolated from 12 collected soil samples using the tablet daub method.Among there strains,we screened 9 Bacillus strains with antagonistic effects on pathogenic bacteria using the plate confrontation method.Then filter paper method were used for secondary screening,isolated and cultured,finally got two strains of Antagonistic Bacillus B23-1 and B01-2 with good antagonistic effects.B01-2was initially deducted belonged to Bacillus amyloliquefaciens and B23-1to Bacillus subtilis by morphological observation and physiological and biochemical identification and ultimately verified the result above via 16S rDNA sequence analysis.By plate streaking cultivation and mixed liquid culturing,we found that B01-2 and B23-1 could grow on the same plate and the growth states were not significant difference compared with single strain cultivation.Then we discovered the number of cells in this case that two stains were put in liquid medium was higher than that in single strain fermentation liquid treatment group in the compound of Bacillus.The lab antagonistic bacteria test showed that the pathogen colony diameter was 1.94cm on average,which was smaller than the single strain controls.With carried out by 2%fermentation filtrate of Bacillus,the spore germination rate at 8.8%was lower than the single strain.The results as following:B01-2 and B23-1 stains had good affinity,the growth could be promoted,antagonistic effect on pathogens could be improved through compound cultivation.In the indoor pot experiment,the disease index of compound Bacillus subtilis fermentation liquid treatment group with 12.5%was lower than that of single strain treatment group,while the incidence of both groups were over 50%.As for control effect of Bambusa Pervariabilis×Dendrocalampsisdaii wilt disease,compound treatment group reached 81%,which was higher than that of single strain treatment.The results showed that:the synergistic effect between B01-2 and B23-1,made it more easily to colonize and grow in the root of hybrid bamboo,thus reduced blight pathogen invasion and suppressed the occurrence of disease.The declined rate of chlorophyll content in the leaves decreased obviously in treatment group with inoculating of compound Bacillus aseptic filtration,and was stable at about 40 SPAD finally,which was higher than that of single Bacillus treatment groups.The PAL,POD,PPO and CAT activities were increased in Hybrid bamboo leaves with all kinds of treatments among which the most significant effect happened in the compound Bacillus treatment which the disease index of Fusarium wilt was lower compared to the single strain treatments.The content of MDA in the foliage of diseased Hybrid bamboos declined at different levels,especially in compound controls,the decreasing effect is obvious.Thus we got a conclusion that the antagonistic Bacillus aseptic filtration was able to reduce the membrane lipid peroxidation in hybrid bamboo leaves,reducing plant tissue damage from MDA and improving the disease resistance of plants.