DNA Markers in Diversity Analysis

Abstract

The study on genetic diversity is critical to success in plant breeding, as it provides information on the quantum of genetic divergence, which serves as a platform for specific breeding objectives. Parental combinations likely to create segregating progenies with maximum genetic potential for further selection, designing introgression program, and selection of parental combinations toward maximization of heterosis are dependent on diversity analysis. Genetic diversity may be assessed using different marker systems, which encompasses morphological, biochemical, and molecular (DNA) markers. With recent advances in genomics research, DNA markers assume much more significance. Using different marker systems, genetic diversity in crop plants may be accessed at species level, at the population level, among germplasm accessions, at an individual genotype level like among pure lines or clones, etc. Intra- and inter-population diversity is measured by various statistical measures, which depend on the type of data set and objective of the study. The relationship between individuals may be displayed using cluster analysis, principal component analysis, principal coordinate analysis, and multi-dimensional scaling. Large array of statistical packages are available to conduct diversity analysis, and a considerable progress has been made with sorghum in analyzing diversity using morphological and molecular markers alone or in combination. In recent past, functional diversity is being assayed using gene and EST-based markers. Using various strategies, core and mini-core collections have been established in sorghum, which are a very important resource for genomic studies in the crop.