The Genetic Diversity Of Forty Eighty Accessions Of Allium Cepa Var. Aggregatum

Potato onion (Allium cepa var. agrogatum Don.), which belongs to the Allium genera ofLiliaceae family, is an annual cultivation herbaceous plant. It is an important vegetable worldwideand condiments because of it rich nutrients and high medicinal value, and widely cultivated in thenortheast area of China, such as Heilongjiang and Jilin Provinces. Because it has short growthperiod, not easy to be affected by diseases or pests, and can effectively enhance land cropping index,reduce pesticide uses, potato onion is suitable for the development of green-foods and has goodmarket prospect. However, the work of the screening and identifying of potato onion resources islacking, its classification is not clear, the synonym and homonym might exist. All of these goagainst the popularization and application of potato onion.In this study, ISSR, SSR, AFLP markers and agronomic traits were analyzed to observe thegenetic diversity of48accessions of potato onion from Heilongjiang and Jilin Provinces in China,which can help us to reveal their ecological genetic relationships and the synonym and homonymthat might exist in potato onion accessions. Moreover, we compared the three molecular markermethods in order to find the method suitable to analyze the genetic diversity of potato onion. Ourwork can provide theoretic basis for the evaluation and identification potato onion resources. Mainresults of this study are as following:1. In the field, the agronomic traits, including bolting, leaf color, seed coat color, wereinvestigated. The genetic similarity coefficients among potato onion resources were calculatedbased on the phenotypic data. Results showed that the genetic similarity coefficients among the48accessions of potato onion were among0.38~1.0. The UPGMA dendrogram based on agronomictraits showed that the48accessions of potato onion can be divided into three classes at the geneticsimilarity coefficient of0.60.2. Thirteen ISSR primers with rich polymorphism, stable amplification and good repeatability were screened from96ISSR primers. With these screened primers,132bands were identified, ofwhich109bands were polymorphic. The ratio of polymorphism is86.2%. On average, each primercan reveal8.4polymorphic sites. The genetic similarity coefficients among the48accessions ofpotato onion were among0.59~0.94, with an average of0.75. The UPGMA dendrogram showedthat the48accessions of potato onion can be divided into three classes at the genetic similaritycoefficient of0.75. The clustering results had obvious connection with their geographic origins.3. Thirty one SSR primers with stable amplification were screened from101pairs of SSRprimers. With these screened primers,116bands were identified, of which66bands werepolymorphic. The ratio of polymorphism is56.9%. On average, each primer can reveal2.9polymorphic sites. The genetic similarity coefficients among the48accessions of potato onion wereamong0.61~0.91, with an average of0.76. The UPGMA dendrogram showed that the48accessions of potato onion can be divided into three classes at the genetic similarity coefficient of0.75. The clustering results had obvious connection with their geographic origins.4. Ten AFLP primer sets were screened from64AFLP primers. With these screened primers,470bands were identified, of which288bands were polymorphic. The ratio of polymorphism is61.3%. On average, each primer can reveal28.8polymorphic sites. The genetic similaritycoefficients among the48accessions of potato onion were among0.59~0.94, with an average of0.72. The UPGMA dendrogram showed that the48accessions of potato onion can be divided intothree classes at the genetic similarity coefficient of0.73. The clustering results had obviousconnection with their geographic origins.5. The clustering results of these three molecular methods were basically identical, but hadgreat differences with the result of agronomic traits analysis. All of the four methods showed thatthe clustering results had obvious connection with their geographic origins. However, someaccessions with long distance geographic origins grouped together. For example,‘Shuangcheng2’from Heilongjiang Province and ‘Baicheng1’ from Jilin Province clustered together, whichindicated that potato onion resources exchanged between Heilongjiang and Jilin Provinces.Moreover, clustering results showed that the relationship between ‘Binxian1’ and ‘Binxian2’,‘Baicheng1’ and ‘Shuangcheng2’,‘Lanxi’ and ‘No.4’ were the closest, but the entire geneticsimilarity coefficient was not1.Based on the evaluation of the genetic diversity of forty eighty accessions of potato onion, we found that the forty eighty accessions of potato onion had rich genetic diversity, the clusteringresults had obvious connection with their geographic origins, and no synonym or homonym wasfound. By comparing the three molecular methods (ISSR, SSR and AFLP), we found that AFLPmarker is the most suitable method when evaluate the genetic diversity of potato onion; ISSR isalso suitable for rapid identification.