Abstract: 【Objective】Cane sugar accounts for 92% of sugar production in China, and hybridization is the most widely used and the most effective way for developing new sugarcane cultivars. Sugarcane germplasm is essential for sugarcane breeding. Selecting parental clones and the cross combinations for hybridization contributes directly to the breeding efficiency. Aimed at providing reference for selecting parental clones and cross combinations, the genetic diversity and similarity among 98 sugarcane germplasm were studied.【Method】Good genomic DNA was extracted from young leaves of 98 sugarcane germplasm collected from 10 countries following the CTAB method, and then were amplified by sequence-related amplified polymorphism molecular markers to analyze genetic diversity and genetic similarity. Separation of the amplified fragments was performed on 5% denaturing polyacrylamide gels, the gels were stained with AgNO3, then “0,1” matrix was obtained according to the electrophoresis result. The number of polymorphic loci, percentage of polymorphic loci, quantity of polymorphic information, effective number of alleles and the indexes of genetic diversity were estimated by POPGENE version 32. The genetic similarity that estimated by NTSYS pc-V. 2.1 was used for UPGMA (unweighted pair group method analysis) and PCA (principal component analysis) to group the sugarcane germplasm. 【Result】Among 1 392 bands detected by 10 selective primer pairs proved by Yunnan Key Laboratory of Sugarcane Genetic Improvement, 1 344 (96.55%) were polymorphic. On average, each primer combination amplified 139.2 loci and 134.4 polymorphic loci. The genetic similarity of 98 sugarcane germplasm ranged from 0.484 to 0.929 with an average of 0.734, the number of polymorphic information was 0.2495, the number of effective alleles for each loci was 1.4092, the average index of genetic diversity was 0.3890. The highest genetic similarity (0.929) was found between KN90-418 and KN90-455, and the lowest (0.484) was found between Yunzhe94-375 and IS76-126. According to the genetic similarity of 0.64, 98 sugarcane germplasm were divided into 4 groups, 5 sugarcane germplasm IK76-48, IS76-126, IK76-22, SES309 and E.SARPET collected from Australia was classified as group I. 1 sugarcane germplasm IS76-199 collected from Australia was classified as group II. KN93-06, 90-110-9 and BURMA were classified as group III; other 89 sugarcane germplasm were classified as group IV which was divided into 9 subgroups (A, B, C, D, E, F, G, H and I ) at the genetic similarity of 0.79. The coefficient of Jaccard was used in PCA and indicated a similar result with cluster analysis that the germplasm with the same region shares high similarity, the similarity within Australian sugarcane germplasm was much lower, and the lowest was found within the germplasm belongs to Erianthus fulvus or Saccharum spontaneum. 【Conclusion】It was concluded that 98 sugarcane germplasm share high genetic similarity and low genetic diversity, the Australian sugarcane germplasm is relatively high in genetic diversity. 90-110-9, KN93-06 and Yuetang00-236 are 3 unique germplasm and are worth utilizing in hybridization.

Key words: sugarcane, germplasm, AFLP, genetic diversity