Genetic diversity within sucrose rich parental pool of sugarcane and its application in sugarcane breeding through hybridization and selection

摘要

Genetic diversity in 82 high sucrose genotypes of sugarcane was estimated using 30 sugarcane specific STMS primers. The overall SI values using three diversity measures viz., Dice, Jaccard's and simple matching methods were 0.69, 0.54 and 0.74 respectively, indicating the existence of moderate diversity among the clones and the scope of improving sucrose content through breeding. The dendrogram analysis among the 82 sugarcane types showed that two pairs of clones (Co 200002 and Co 86005 and, Co 91017 and 89005) were identical. Though the clustering of clones reflected the pedigree relationship between the cultivars, deviations from this were observed and could be attributed to the high heterozygosity and polyploidy of the genus Saccharum that lead to gross differences in phenotype and genotype. The more diverse clones were Co 87009, Co 86002, Co 90006, Co 86014, Co 775, Co 87011 and Co 85037. Out of 3321 possible combinations, 443 combinations were genetically more similar (SI = 0.83) which might not provide incremental gains through hybridization, while 813 combinations (SI = 0.69) were genetically more diverse and 2206 combinations showed moderate diversity (SI = 0.70-0.82). Such diverse clones and combinations have immediate application in breeding for improving efficiency and precision in sugarcane breeding. Based on diversity estimates, hybridization involving four genetically diverse, three genetically similar and three with intermediate similarities were affected and progeny performance correlated with genetic diversity. A strong correlation (-0.7265) between genetic diversity and cross performance and cross selection rate from crosses with high and medium diversity indicated the importance of diversity estimates in the choice of parents and to estimate genetically more similar crosses.