Research On The Genetic Diversity And Angular Leaf Spot Disease Resistance Of Persimmon Germplasm Resources In Guangxi

Guangxi is one of the biggest persimmon production areas in China, it possesses ample persimmon germplasm resources due to its long histry of persimmon production and special geographical climate. The basis of research on persimmon resources in Guangxi is weak and the germplasm information is lack, which affects the exploitation, utilization and protection of persimmon germplasm resources in Guangxi. In order to reveal the situation, genetic background and diversity information of germplasm resources and provide the scientific basis of classification, preservation, utilization, introduction, early identification of disease resistance and breeding of persimmon germplasms in Guangxi, the study was conducted to investigate persimmon resources in Guangxi and their utilization condition. The persimmon germplasm resources from different eco-climatic zones were collected and preserved at the persimmon germplasm repository. Morphologic system cluster and fuzzy comprehensive evaluation analysis methods were used to analyze the diversity and comprehensive characters of the gernplasms. SCoT and SSR molecular markers technologies were used to study the diversity of the persimmon germplasm resources as well. Mean while, the effect of SOD, POD, CAT, PAL, MDA and GSH of persimmon leaves on the resistance of angular leaf spot disease were studied on the basis of survey of natural occurrence and artificial inoculation. cDNA-SCoT method was firstly used in persimmon germplasm research and studied the different expression of genes between the susceptive and resistant germplasms; the purpose of the study is to provide scientific basis of classification, preservation, utilization, introduction, early identification of resistance and breeding of persimmon germplasms. The Main conclusions are as follows:1. The Investigation of persimmon germplasm resources in Guangxi and its development and utilization stateIn order to provide materials and basis for persimmon resources utilization, introduction and domestication, conservation and breeding, the persimmon germplasm resources from different eco-climatic zones in Guangxi were surveied and investigated,104accessions of germplasms which belong to Diospyros. kaki Thunb., Diospyros.lotus Linn, Diospyros. oleifera Cheng., Diospyros. glaucifolia Mete, Diospyros. Virniana Liun. and Diospyros. rhombifolia Hems were collected, they were preserved in the persimmon germplasm repository in Guangxi university. The investigation indicated that the persimmon industry in Guangxi have got a rapid development in recent years, the change of persimmon planting area and production area was small, but the total yield and average yield per unit were increasing yearly. Meanwhile, there were some problems in the persimmon industry in Guangxi, such as the exploitation and utilization of persimmon germplasm resources was insufficient, and with single variety, unreasonably growing structure, low degree of cultivation standardization, the storage and processing was not deep and the processing products were few; for thess reasons, countermeasures to promote the development of persimmon industry in Guangxi were put forward.2. Analysis and comprehensive evaluation of the genetic diversity of persimmon Germplasm resources in GuangxiThe persimmon germplasm resources in Guangxi possessed ample diversity in phenotype, the Euclidean distances between44phenotypic traits used in the study were far, which indicated that these traits were independent and could distinguish the persimmon germplasms well. Phenotypic cluster analysis could cluster some germplasms which possessed some similar characteristics together, it could be important basis for classification of persimmon cultivars. Owing to the shortcoming of the phenotypic cluster analysis, it had better combined with some other identification methods to further distinguish the relationship, such as molecular markers. The result of fuzzy comprehensive evaluation analysis showed that the fuzzy comprehensive evaluation index of persimmon cultivars Yueshi, Niuxinshi, Dafangshi, Jingshi, Jixinshi, Xiaofangshi Huoshi and some seedlings were high, their fruit comprehensive characters were excellent, it’s suggested that these excellent varieties and seedling should be used in the persimmon exploitation and utilization. Some excellent seedling which possessed excellent single trait was not suitable for direct planting, but they could be used as materials in persimmon cultivar improvement.3. The genetic diversity of persimmon germplasm resources in Guangxi revealed by molecular markersThe persimmon germplasm resources collected from different eco-climatic zones in Guangxi were analysized and identified by start condone targeted (SCoT) polymorphism molecular marker; they were compared with SSR molecular markers. The result showed there were some differences between SCoT and SSR molecular markers, but the results of the two methods are consistent in whole; two molecular markers methods could distinguish the germplasms from each other, they could be used as powerful tools in the classification of persimmon germplasm resources. The cluster analysis conducted by UPGMA showed that the genetic diversity of persimmon germplasm resources in Guangxi was ample, the germplasms belong to Diospyros. kaki Thunb., Diospyros. oleifera Cheng, and Diospyros.lotus Linn were clustered into different groups, there was a crossover among Diospyros. kaki Thunb. and Diospyros. Virniana Liun. Guangxi natural persimmon germplasm resources possessed broad background and the genetic diversity was abundant; a great degree of genetic differentiation happened among the populations, it might due to the destruction of inhabit environment and the gene flow being blocked.4. Research on the resistance to persimmon angular leaf spot diease of persimmon germplasm resouces in GuangxiThere was ample diversity of resistance to persimmon angular leaf spot disease among different persimmon germplasms. Germplasms of Diospyros. kaki Thunb and some Diospyros. Virniana Liun seedlings had good resistance to angular leaf spot disease. The content or activity of SOD, POD, PAL, MDA in leaves of each persimmon germplasms increased and showed certain patterns, which indicated that the changes of activity or content of these enzyme was related to the resistance to angular leaf spot disease. The changes of CAT activity and GSH content also had some certain regularity, but they weren’t related to angular leaf spot disease resistance of susceptibility and resistance persimmon germplasms. Gene differential expression of susceptive and resistant persimmon germplasms was studied by cDNA-SCoT technology, the result showed that SCoT molecular marker technology could be associated with persimmon leaf spot disease stress response,13gene fragments related with persimmon angular leaf spot disease stress were obtained,7of them had a high homology with the known genes including some genes which played important roles in plant stress defence. The other6differential expression fragments had no homologous sequences with known function in the database.