Study On Microbial Ecology And Jujube Fruit Shrink Disease

As the growing area increase jujube tree in recent years, various kinds of diseases of jujube have been exposed, especially Jujube-Fruit-Shrink-Disease, which symptom just performant on date fruit and more complex, has become a significant problem in jujube industry. The disease always outbreak in mature period of the jujube, had a serious impact on the jujube quality and value for goods, even made a disaster. Therefore, the research on fruit shrink disease prevention and select disease-resistant varieties is extremely important.The paper have studied common jujube cultivars, the main materials are Qiyuexian、 Junzao、 Lizao and Muzao.We isolated, purified, culture and determine the pathogenicity of JFSD pathogens, identified the pathogens by morphology and molecular biology identification; explore the microeconomic factors which affect fruit shrink disease from jujube microbial ecology point; and study the enzyme activity between pre and post JFSD infection. The results are as follows:1. The investigation of JFSD infection in field showed:The rate of infected fruit was increasing year by year in the same orchard. The susceptibility of Zizyphus jujube Mill. cv."Muzao" was the lightest, followed by "Jinzao","Fengmiguan","Zanhuangdazao","Goutouzao","Lizao","Junzao" and "Qiyuexian" was the heaviest.2. Using conventional tissue isolation methods, isolated, purified, culture and determine the pathogenicity of JFSD pathogens, we got three fungal species and one bacterial species:F1, F3, F4and B2, they can cause the typical JFSD symptoms by inoculation alone or mixed, fitting Koch’s postulates, These results proved that the strains Fl, F3, F4and B2were pathogens of JFSD. Combining classical morphological and molecular identification methods, F1was identified as Alternaria, F3was identified as Phoma spp, F4was identified as Coniothyrium spp, B2was identified as Bacillus amyloliquefaciens.3. There were969strains of endophytic microorganism, including492strains of fungi,418strains of bacteria and28strains of actinomycetes. By morphology and16S-ITS-PCR amplification methods, they were classified into20genera, the dominant genus are Alternaria, Phoma spp and Fusarium. By16SrDNA amplification method, bacterias were identified classified into10genera, the dominant genus is Bacillu. Pathogens were mostly dominant microorganism. So we can confirm thar the pathogen may have long-term latent infection in Jujube, and laid the foundation for reseaching JFSD infected law. 4. By studying microflora of different parts for jujube (inside, medium, outside), it was showed that the largest number of fungi is the part of outiside, followed by the middle part,the fewest number of fungi is the part between the pit and peel of date. The distribution of bacteria and actinomycetes is same as fungus.5. By determining enzyme activity of SOD、POD、CAT、PAL and MDA content in different parts of the health and diseased jujube, the results showed that:The enzyme activities changed differently in different varieties of jujube after infected JFSD, after infection, SOD activity and MDA content was negatively to disease resistance, POD activity was positively to disease resistance, PAL and CAT activities increased after infection, the increases of PAL activity was negatively correlated with disease resistance; The enzyme activities and MDA content were different after infected JFSD in different parts of the same species. For Qiyuexian, the four physiological activities and MDA content in the part of outside were highest in healthy fruit, the activities and MDA content in medium part was close or slightly higher than in internal part. However, in diseased fruit, the four physiological activities and MDA content in the part of outside were highest, followed by the internal part, the mediun part was lowest.