Crop plant evolution either natural or human-directed, is primarily based on existing genetic diversity in the population. Diversity can be described as the degree of differentiation between or within species. Genetic diversity becomes more important in context of climate change and associated unforeseen events as it may serve as the reservoir of many novel traits conferring tolerance to different biotic and abiotic stresses. Genetic diversity is the underlying cause of many agriculturally important phenomena like heterosis and transgressive segregation. Diverse lines are needed for defect correction of commercial varieties and development of novel varieties. Hence, identification of diverse lines (if available), creation of diversity (if not available or limited) and its subsequent utilization are the major goals of any crop improvement programmes. The genetic diversity of agricultural crops is represented by land races, modern cultivars, Obsolete cultivars, wild forms of cultivated species, wild relatives, mutants, advanced breeding lines.4

The genetic diversity of improved rice varieties has been substantially shaped by breeding goals, leading to differentiation between indica and japonica cultivars. Taiwanese landraces with different origins possess various and unique genetic backgrounds and provides diverse genetic variation for association mapping to unveil useful genes and is a precious genetic reservoir for rice improvement.3 Several traits including pest resistance, productivity traits, higher nutritional value, and salt stress tolerance have been introduced from wild Solanum pimpinellifolium to the cultivated tomato. Like wild species, landraces also contain valuable traits that are absent from modern cultivated gene pools. For instance, submergence tolerance contributed by the SUB1A gene in modern rice varieties originated in an Indian landrace of O. sativa, FR13A1.The core set is regarded as the gateway to unravel the diversity estimate. The core set will prove useful in different crop improvement programs including gene discovery through association mapping. In addition, the diverse lines will be utilized in crossing programs for the improvement of different traits in chickpea.2 Genetic diversity has now been acknowledged as a specific area that can contribute in food and nutritional security. There is a need of paradigm shift in plant breeding focusing on diverse genetic resources. Genetic diversity of crop plants is the foundation for the sustainable development of new varieties. So there is a need to characterize the diverse genetic resources using different statistical tools and utilize them in the breeding programme. The diversity indicated by different analysis can further be utilized in heterosis breeding, transgressive breeding and introgression of alien genes for specific traits.4

 REFERENCES:

 1. DWIVEDI, S.L., CECCARELLI, S., BLAIR, M.W., UPADHYAYA, H.D., ARE, A.K. AND ORTIZ, R., 2016. Landrace germplasm for improving yield and abiotic stress adaptation. Trends in plant science, 21(1),31-42. 

2. FAYAZ, H., MIR, A.H., TYAGI, S., WANI, A.A., JAN, N., YASIN, M., MIR, J.I., MONDAL, B., KHAN, M.A. AND MIR, R.R., 2021. Assessment of molecular genetic diversity of 384 chickpea genotypes and development of core set of 192 genotypes for chickpea improvement programs. Genetic Resources and Crop Evolution.1-13. 

3. HOUR, A.L., HSIEH, W.H., CHANG, S.H., WU, Y.P., CHIN, H.S. AND LIN, Y.R., 2020. Genetic diversity of landraces and improved varieties of rice (Oryza sativa L.) in Taiwan. Rice, 13, 1-12. 

4. SWARUP, S., CARGILL, E.J., CROSBY, K., FLAGEL, L., KNISKERN, J. AND GLENN, K.C., 2021. Genetic diversity is indispensable for plant breeding to improve crops. Crop Science, 61(2),839-852.