Genetic Diversity, Erosion, and Population Structure in Cotton Genetic Resources

Abstract

It is strongly believed that the wide genetic variability within the cotton (Gossypium spp.,) increases their chance for adaptation to changing harmful environments, and thus upsurge the likelihood of long-term survival of such unusual and important cash crop in the world. Given, the importance of cotton in the world economy and its usefulness to the human, cotton genetic resources should be conserved effectively and managed wisely, since such cotton genetic resources are used as the raw material for breeding new cultivars and act as a reservoir, and/or buffer against ecological and economic changes. However, the trend is reverse as there has been significant loss of genetic diversity during the past couple of decades, and the process of genetic erosion continues. Although, the narrow genetic diversity that exists in cotton has been noticed for more than two decades, there is little data on its amount and extent. Besides the threatening genetic base of future cotton breeding programs, erosion of cotton genetic resources could pose a severe threat to the world’s natural fiber production in the long-term, since loss of genetic variation may decrease the potential for a species to persist in the face of abiotic and biotic environmental changes. Future progress in the improvement of cotton largely depends on discovery, collection, and immediate conservation of genetic resources such as wild progenitors and landraces of Gossypium for their effective and sustainable utilization in the cotton breeding program. This chapter describes the challenges to cotton genetic diversity, presents the strategies that are being implemented to reverse the erosion of that diversity, outlines several gaps in our knowledge, and describes strategies that must be addressed to make such approaches more effective. Deployment of biotechnological tools in the study and conservation of cotton genetic resources are also highlighted in this chapter. Integration of the knowledge about evolution and natural population structure of domesticated Gossypium species combined with emerging sequence and functional genomics information will lead to the better management of cotton germplasm resources and more efficient utilization of natural variation for cotton genetic improvement.