Of approximately 300,000 species of flowering plants, humankind is fed and clothed by only several dozen major crops. These crops were largely developed by aboriginal domesticators in ancient times from often obscure origins. Interdisciplinary studies combining the tools of evolutionary and molecular biology have provided novel insights into the origins of modern crop species, including identification of wild progenitors and patterns of genetic diversity. Plant domestication has been characterized by sequential genetic bottlenecks, whereby relatively large gene pools were repeatedly winnowed during selection of modern cultivars and breeding populations. Crop improvement has been accompanied by dramatic morphological alterations, thereby providing model systems for analyses of the evolutionary and developmental genetics underlying morphological innovation in nature. These analyses are facilitated by genomic and proteomic approaches. Because many important crops, including wheat, maize, and cotton, are polyploids, these species provide model organismal frameworks for analyzing the fate of duplicated genes and genomes following polyploid formation. Polyploidy is associated with novel genomic interactions and molecular genetic mechanisms, and is suggested to have opened up new avenues for agronomic improvement.

Key words: cotton, genetic diversity, maize, morphological evolution, Plant domestication, polyploidy