ANALYSIS OF GENETIC SIMILARITY AMONG 48 SUGARCANE VARIETIES USING MICROSATELLITE DNA SEQUENCES

摘要

Genetic diversity is an important factor in sugarcane breeding programs since, if there is sufficient variability to identify genetically diverse parents, specific crossing plans may be designed. In the selection of parents for crosses, it is important to combine dissimilar genotypes in order to get a high level of hybrid vigour. Microsatellite DNA sequences or simple-sequence repeats (SSRs) are useful as descriptors of plant genetic variation. The objective of this research was to analyse the genetic similarity of 48 sugarcane varieties by means of SSR markers to identify contrasting parents to be used for crossing in the breeding program. Six primer pairs developed by CIRAD were used to amplify microsatellites. Data of the bands (presence-absence) were used to quantify genetic similarity by the Dice coefficient and cluster analysis by the UPGMA method. According to similarity, the values between each pair of varieties ranged from 0 to 0.52, with an average of 0.11. It indicates that there is diverse DNA among the 48 varieties. The highest values in similarity were between the combinations PR75-2002 and PR78-3025 (0.52); Co421 and CP57-603 (0.48); Ja64-20 and L68-40 (0.47); PR75-2002 and PR87-2048 (0.45); PR78-3025 and PR87-2048 (0.43); and L68-40 and L80-38 (0.41). Cluster analysis detected 25 groups with a similarity coefficient of 0.28. In the crossing campaign 2003-2004, crosses were made taking into account the information obtained in this study. SSR markers provide a useful tool for analysis of genetic similarity in sugarcane varieties.