Investigation, Characterization And Genetic Diversity Study On Early Mature Seedling Litchi Resources In Southwest Guangxi

Guangxi is one of the originating regions of litchi in china and has plenty of seeding litchi germplasm, especially early maturity characters are obvious in southwest Guangxi. However, these early mature seeding litchi resources are destroyed gradually, and the quantity is decreasing because of less protection and excessively hewing. It is very necessary to perform further study on early mature seeding litchi resource in southwest Guangxi. Based on this, field survey, morphological identification, ISSR analysis and karyotype analysis were applied to characterize the early mature seeding litchi resources and to assess their genetic diversity. The results were summarized as follows:1. The early mature seeding litchi resource mainly distributed in Longzhou, Daxin, Tiandeng, Jingxi, Debao, Tiandong, Tianyang, Dahua, Du'an, and centralized the place that people activity more frequently. The 69 seeding plants were morphological identified, and the results showed that the early mature seedling litchi resources of southwestern Guangxi were abundant genetic diversity. The average tree age was 69.6, height was 6.6m～20.5m; five types of leaf shape; long inflorescence, the average was 25.1cm; eight types of fruit shape, the weigh was 7.0g～29.2g, the soluble solid content was 10.1%～18.2%, the edible rate of the pulp was 31.8%～69.0%. The pulp was crisp, no flow juice, but the flavor was acid. They matured in early or middle of May.2. The 69 seeding plants were used to analyze based on Q-style cluster. At the Euclidean distance 16.5, the 69 seeding plants were divided into three groups. Group one included 34 seeding plants, which belonged to sharp-protruding tortoise-shaped lobe and sharp pointed tortoise-shaped lobe tip; Group two included 20 seeding plants, which belonged to sharp-protruding tortoise-shaped lobe and obtuse tortoise-shaped lobe tip; Group three included 15 seeding plants, which belonged to nipple-protruding tortoise-shaped lobe and sharp pointed tortoise-shaped lobe tip. 3. Fruit characteristics of 69 early mature litchi seedling plants were evaluated with Fuzzy comprehensive analysis methods. The NO.1 was DB20 that was middle-sized, bright red pericarp, crisp and no acerbity, sweet and honey fragrant. It had some edible value, but edible rate of the pulp was was low because of its big seed. So it couldn't used to commercial cultivation.4. Ten pairs of ISSR primers were used to analyze 83 early litchi (variety) plants. The results showed that the early mature seeding litchi resource in southwest Guangxi had abundant genetic diversity, and there were hereditary difference among different areas.5. The genetic diversity and genetic structure about 6 wild populations of the early mature seeding litchi resources in southwest Guangxi were studied by ISSR markers. The genetic variation came from both inside and outside populations, and mainly from inside population.6. The results showed that the chromosome was composed of the m, sm, st and t chromosome by karyotype analysis. The diversity mainly display the number of different chromosome types and its site in the karyotype. The mean of ratio (longest/shortest), main ratio of arm, asymmetric coefficient value were 2.17～4.85,1.81～3.43,60.95%～68.36%. The karyotype were mainly indentified as symmetry type of 2B or 2C.7. Morphological identification, ISSR analysis and karyotype analysis were applied to assess their genetic diversity. The results of the first two methods showed that the early mature seedling litchi resource of southwestern Guangxi were abundant genetic diversity by before two kinds method, but karyotype analysis method was not.