Evaluation Of Genetic Diversity Of Akebia Trifoliata Germplasm Resources And Identification Of Leaf Spot Pathogens

Akebia trifoliata is a plant with great potential of medicinal value,edible value,ornamental value and landscape application value.With the popularization and acceptance of various values of Akebia trifoliata,the wild resources have been unable to meet the demand,and the market demand is also in short supply.It is urgent to select and cultivate its improved varieties and cultivation,and the collection and evaluation of Akebia trifoliata germplasm resources is the basis and prerequisite for breeding and cultivation of improved varieties.In order to improve the evaluation of germplasm resources of Akebia trifoliata,select high-quality germplasm,and then provide sufficient conditions for breeding,genetic improvement and germplasm innovation,this paper uses morphological markers and molecular markers to evaluate the genetic diversity of Akebia trifoliata seed germplasm resources.In addition,according to Koch’s law,the leaf spot pathogen of Akebia trifoliata was isolated and identified,which will be used to evaluate the disease resistance of seed germplasm resources of Akebia trifoliata and select the Germplasm with strong disease resistance.It is also to improve the evaluation of germplasm resources of Akebia trifoliata and lay a foundation for innovative breeding and giving full play to its economic value.The results are as follows:1.Morphological marker results.A field investigation was conducted on the 19 characters（10 quantitative characters and 9 quality characters）of 96 provenances of Akebia trifoliata.The data were processed by descriptive statistics,correlation analysis,principal component analysis and cluster analysis.The results showed that the variation coefficient of 10 quantitative characters ranged from 12.9%to 41.4%;Shannon genetic diversity index of 9 quality characters ranged from 0.59 to 1.85,and the other 8 quality characters were all greater than 1.00 except for plant type;fruit characters were not only significantly related to fruit characters,but also leaf characters were not only significantly related to leaf characters;19 characters were integrated into 5 main components,and the cumulative contribution rate reached 70.867%.The first principal component was mainly related to fruit character,the second principal component was mainly related to leaf length and width,the third principal component was mainly related to leaf shape,the fourth principal component was mainly related to plant infection,the fifth principal component was mainly related to leaf ornamental character.It was divided into three parts by spss23.0square Euclidean distance Wald method Large group,the first and second groups had fruit,the third group had no fruit.The first was the group with larger leaves,the second was the group with better fruit disease,and the third was the evacuation type without fruit type.2.Molecular marker results.The ISSR-PCR system of Akebia trifoliata was established by orthogonal test and single factor test:DNA template was 70ng,Mg²⁺concentration was 2.5mmol/l,Taq DNA polymerase dosage was 0.75U,d NTPs concentration was 0.4mmol/L,primer concentration was 0.5μmol/l.10 ISSR primers with clear stability,good repeatability and high polymorphism were screened out.96 germplasm resources of Akebia trifoliata were expanded.The percentage of polymorphic loci was 97.42%,Shannon’s information index（I）was 0.4469,the observed allele number（NA）was 1.9742,the effective alleles number（NE）was 1.4768,and the Nei’s gene diversity index（H）was0.2902 The genetic diversity of resources is very rich,which contains a wide range of genetic variation.According to the cluster analysis of GS value by unweighted pairing arithmetic mean（UPMGA）,96 germplasm resources of Akebia trifoliata could be grouped into three groups when the genetic similarity coefficient was 0.661.3.Identification results of pathogenic bacteria.According to Koch’s law,four pathogens were isolated and purified from the leaf spots of Akebia trifoliata.Combining the results of the analysis of the genetic relationship with the morphological characteristics and culture characteristics of the colony,the pathogenic species were identified,including Colletotrichum acutatum,Botryosphaeria dothidea,Phomopsis sp.,Alternaria tenuissima.