| Litchi genus belongs to the Sapindaceae family and has two species,Litchi chinensis Sonn. and L. philippinensis Radl.. L.chinensis Sonn. is the only cultivated species and two Litchi varieties,L. chinensis var. fulvosus YQ Lee and L. chinensis var. spontaneous Pei were found in Yunnan. China is the center of Litchi's origin and demostication,the main production country recently in the world,produced 95% of the total production in the world,cultivated more than 600000 ha .Based on the investigation of Litchi cultivar resource in FuJian Province,in this study we took advantage of ISSR molecular marker,researched the genetic diversity of 78 Litchi samples,provided scientific basis in effectivet protcetion and rational ultilization for Litchi gernplasm resource in FuJian Province and genetic background for the breeding of Litchi new variety. Main study results are as follow:In this study,inter-simple sequence repeat (ISSR) method was applied to detect genetic variation of cultivated Litchi from 78 samples. The results could provide scientific basis for making right protection strategy and help to foster new cultivars. The main results were as follow:1. Because Litchi is rich in Phenolic compounds and polysacchrides which resulted in the difficulty in the DNA extraction and purification,improved method of SDS is used to ectract Litchi DNA,the amount and purity of DNA can meet the demand of ISSR analysis,and DNA extraction method for Litchi is put for forward。2. The technological system of ISSR-PCR reaction of Litchi has been built up. In the 20μL reaction system,The results showed that the optimum reaction condition of ISSR was 20 ng DNA template, 0.15μmol/L ISSR primer, 1.25 UTaq DNA polymerase,0.15μmol/L dNTPand annealing temperature of 54~56℃in each reaction system of 20μL.According to the system,the experimental steps are as follows. 5 min predenaturation at 94℃,30 seconds denaturation at 94℃,60 seconds annealing,90 seconds extension at 72℃. The cycle repeats forty times and ends in 7 min extention at 72℃.3. A total of 11 ISSR primers were employed on 78 individuals of cultivated Litchi from 96 primers,and 127 scorable amplified polymorphic were detected,of which 122(96.06%) were polymorphic loci. And this research found that primers containing(AG)n,(CA)n,(AC)n sequence resulted in of amplified polymorphism of Litchi. So (TC)n,(GT)n,(TG)n sequence is higher levels in Litchi genome.4. According to the clustering analysis of ISSR results,thess 78 samples were clustered, it proved that the genetic similarity index was 0.454～0.985. The basis of ISSR analysis for the trial of 78 varieties of cluster analysis results showed that: among them in the genetic similarity coefficient between 0.454 ~ 0.985, the genetic diversity ,genetic similarity and genetic relationship between different species are revealed,and it is a theoretical basis of distant hybridization litchi, litchi varieties access to quality provides the basis to improve the breeding efficiency .5. They explanated the relationship between the ancient settlement of litchi and the cultivation now, explained varieties homonym with the problem of synonyms, and explained the production traits of some breeds instability.
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