Genetic diversity in sugarcane hybrids (Saccharum spp complex) grown in tropical India based on STMS markers

Understanding the pattern of diversity among the commercial sugarcane hybrids is highly useful to sugarcane breeders in planning and broadening the genetic base. Genetic analysis of 22 cultivated sugarcane hybrids representing all agro-eco climatic regions of tropical India was carried out using ten sequence tagged microsatellite sites (STMS) primers. A total of 127 markers were amplified, of which 78.74% were polymorphic with an average of 10 polymorphic products per STMS primer. Jaccard’s similarity coefficient value estimated between closely related hybrids was 0.889 while the lowest coefficient value of 0.574 was detected with distantly related hybrids. The average genetic similarity among the hybrids was ~84.8%. These results indicated the existence of low level of genetic diversity among the commercial hybrids under cultivation. Unweighted pair group method with arithmetic averages (UPGMA) cluster analysis detected five major clusters. Cluster II consisted of four varieties which had Co 775 as one of the parents. Variety CoC 671 and its somaclone Co 94012 were grouped into cluster IIa. Varieties grouped in the cluster III had either CoC 671 or Co 775 in their genealogy indicating the influence of parental genome contribution to clustering. Varieties developed for east coast zone were grouped in the clusters IIb, IIIb, IIIc and IVe which indicated the influence of adaptation of varieties to particular agro-climatic condition. The study also identified 12 unique markers which can be useful in varietal identification and rouging in seed plot.