Evaluation of genetic diversity using biochemical markers in sugarcane germplasm collection

Sugarcane (Saccharum spp.) is a genetically complex crop of great economic importance in tropical and subtropical countries around the world. Currently, main concern is to characterize sugarcane germplasm based on protein profiling which provide key information on genetic diversity that can be used in breeding for yield and quality traits. The present study aimed to evaluate complement of leaf proteins using SDS-PAGE technique in sugarcane accessions as an alternative biochemical marker system for DNA-based markers used in genetic diversity analysis. DNA-based molecular markers are usually employed in genetic diversity analysis, but assays based on these markers are relatively expensive, time-consuming and tedious operations than alternative protein-based biochemical markers. To conduct experiment, the protein extract was subjected to SDS–polyacrylamide gel electrophoresis using a rapid and economical Experion automated electrophoretic resolution system. The germplasm accessions represented different origins in the Indian subcontinent and four clones from Jawa, Indonesia. A total of 748 protein bands were obtained, of which 452 (54.0%) bands were found polymorphic in the entire set of 50 accessions used in the study. The dendrogram constructed using UPGMA algorithm divided all the accessions into two major groups consisting five clusters. The clustering pattern indicated that genetic diversity among Saccharum spontaneum and subtropical accessions was greater, which could be due to their unique genetic constitution. Genetic diversity between S. spontaneum and UPCSR or S. officinarum or S. robustum accessions was less that indicates shared protein pool, which may be due to common ancestry and exchange of germplasm among different breeding groups. Analysis of the dendrogram was not allowed to distinguish interspecific hybrids from foreign commercial hybrids originated in India and Indonesia. Accessions from extensive geographic sources differed considerably, but it was difficult to establish any relationship between the place of origin and the nature of clustering. The obtained protein profiling data indicated a biochemical polymorphism and segregating clustering pattern that may be informative for phylogenetic studies. The degree of genetic diversity assessed using biochemical/protein markers will be useful in future sugarcane breeding programs to select promising parental lines.