The Germplasm Evaluation And Correlation Analysis Of Mango Bacterial Black Spot Disease Resistance

Mango bacterial black spot disease is an important disease in the process of mango production.Once a mango infected,it will lose its commercial value,and even lose its harvest in severe cases.At present,this disease is mainly controlled by daily cultivation management and spraying of chemical pesticides.The efficiency of prevention and control is low and it is easy to cause environmental pollution.According to scientific research,cultivating mango bacterial black spot disease-resistant varieties is an effective way to prevent the disease,analyzing the genetic mechanism of the disease resistance of mango can provide a theoretical basis for the creation of new high-quality bacterial black spot disease-resistant varieties.In order to clarify the genetic characteristics of bacterial black spot disease resistance,the experiment evaluated the traits of resistance to bacterial black spot disease in 33 mango germplasms such as Kate and B74 by indoor inoculation method.And the genetic diversity of 33 mango germplasm materials was analyzed by SSR,a kind of molecular markers,and the genetic differences between mango germplasm materials were acquired;on the basis of analyzing the population structure of the germplasm materials and the evaluation of variety bacterial black spot resistance,combined with the simplified genome sequencing,we obtained the locus significantly associated with the resistance to bacterial black spot disease.The locus provides reference and molecular marker resources for subsequent bacterial black spot disease resistance breeding research,and accelerates the process of mango bacterial black spot disease resistance breeding.Identification of mango bacterial black spot disease resistance: 33 common mango cultivars,such as Kate,B74 and Jin Huang,were selected and the method of stab wound inoculation of mango fruit in vitro was adopted,according to the susceptibility of different mango germplasms,the mango bacterial black spot disease resistance was graded in combination with evaluation methods such as systematic cluster analysis,average spot diameter method,disease index method and so on.The results showed that among the 33 mango germplasms,B74 and KRS were high resistant to bacterial black spot disease;five varieties were medium bacterial black spot disease resistance materials such as Zillate and Ying zui;fifteen varieties were medium bacterial black spot disease sensitive materials such as 0902,0905,Shengxin,Yuwen;there were seven susceptible materials such as Guangxi No.4,Dong zhen hong mang and Datou mango;four varieties were high sensitive materials such as Keitt and Red Ivory mango.Through DPS data processing software for data processing,cluster analysis to obtain disease-resistant phylogenetic trees of different varieties.Two high bacterial black spot disease resistant varieties and four high bacterial black spot disease sensitive varieties can be used for further research on mango bacterial black spot disease disease resistance breeding.The analysis of mango genetic diversity which is based on SSR markers: 30 pairs of SSR primers with clear bands and better polymorphism were selected from 109 pairs of SSR primers.A total of 203 bands were amplified by 30 pairs of primers,of which159 bands were polymorphic,the polymorphic ratio was 79.72%.Each pair of primer can amplify 3-9 polymorphic bands.On average,each pair of primers can amplify 5.3polymorphic bands.The Molecular weight of the amplified bands is mostly between100bp-400 bp.Clustering results show that the 33 kinds of mango germplasm can be divided into 6 groups at the genetic distance of 0.63.By comparing the polyacrylamide gel electrophoresis of mango bacterial black spot disease high-resistance varieties B74,KRS,bacterial black spot disease medium-resistance varieties Zillate,Aomang et al.,and all bacterial black spot disease susceptible varieties,it was found that the mango varieties that were resistant to bacterial black spot disease were all amplified with Six different types of bands,and none of these 6 types of bands were found in the electrophoresis of susceptible varieties.Therefore,six bands with different sizes that may be related to the resistance of mango bacterial black spot disease were obtained.The stripe sizes are 100 kb,150kb,180 kb,200kb,300 kb,and 400 kb,respectively.Simplified genome sequencing of mango germplasm: Simplified genome sequencing of 33 mango samples.Based on SNP information,the distance between products was calculated,and the samples were clustered to obtain the phylogenetic evolution tree of the samples.33 mango varieties were divided into 6 groups.Using the software MISA to search all tags to find the SSR fragments in the tags.Combined with the genetic diversity analysis results of mango based on SSR markers and the evaluation results of the resistance of mango germplasm to bacterial black spot disease,a correlation analysis was conducted and it was found that there are three types of all SSR fragments,111 SSR fragments with a size of about 100 kb,150kb and 200 kb may be related to the resistance of Mango bacterial black spot disease.In this experiment,simplified genome sequencing and SSR markers were used to research the mechabism of mango bacterial black spot disease resistance,which was laid for the subsequent genome research of mango and the breeding of mango bacterial spot disease resistance.