Genetic Diversity And Classification Of Longan Germplasm As Revealed By Molecular Markers

Longan(Dimocarpus longan Lour.) originated from South China and North Vietnam with abundant germplasm. The classification of longan evolved from morphological diversity to genetic diversity.The studies on longan classification involved the fields of morphology, palynology, biochemistry and molecular biochemistry. Some classification points weren't consistant because of the different standard adopted and each kind of classification's limitation. This research work is mainly studied on the genetic diversity of longan germplasm by applying AFLP.The aim is to set up a classification system on longan and supply theoretical basis for conservation and utilization as well as technological foundation for cultivar registration, identification and protection. The main results were briefly summarized as follows:1. High molecule weight DNA and AFLP fingerprint can be obtained by using the improved methods of SDS and CTAB .The DNA extraction buffer and nuclei lysis buffer should contain different concentration of PVP and BME according to different degree of greenness.2. Two pairs of AFLP primer EcoR I ACT+Mse I CTT and EcoR I ACT+Mse I CTC were selected to analyses 46 longan materials, the number of amplified bands is 111, which is enough to distinguish the 46 materials from each other. The results showed that it is feasible for using these two pairs of primers in AFLP analysis.3. Based on the AFLP data, the tested materials were clustered into 11 groups on coefficient level 0.76.The cluster results is somewhat different from the traditional classification based on morphology, palynoloy, isoenzyme and RAPD markers.4. The similar coeffients of the 46 cultivars changed from 0.62 to 0.93, and the polymorphic rate from 0.2703 to 0.4955, most of the values lied between 0.3000 and 0.4000.The analysis of genetic diversity among longan cultivars indicated that the genetic diversity among longan cultivars are less than that of banana or litchi.5.The result showed that the Fujian Dongbi was different from Guangdong Dongbi and they were different types from Kaiyuanshi Dongbi. Shuangmamu and Qingpi, Chilongyan and Shuiyan, are different types. Zaoshu 1 was supposed to be a new type.