Submitted to: Managing Plant Genetic Resources
Publication Type: Book / chapter
Publication Acceptance Date: 12/2/2002
Publication Date: 12/2/2002
Citation: Kohel, R.J., Yu, J. 2002. Molecular characterization of Gossypium germplasm for cotton improvement. In: Engels, J.M.M., Rao, V.R., Brown, A.H.D., Jackson, M.T., editors. Managing Plant Genetic Resources. Cambridge, MA: CAB International Publishing, Inc. p. 67-75. Interpretive Summary: Cotton germplasm serves as a gene bank for improvement of cotton natural fiber and oilseed. There are 50 species recognized in genus Gossipium and only four are cultivated in modern agriculture. Currently over 7,000 Gossypium accessions are maintained in the U.S. National Collection of Cotton Germplasm. In addition, about 6,000 Gossypium accessions are coming from Russia and other countries. However, a vast majority of the cotton collection remains untapped because of technological limitations. With the development of DNA markers and other molecular tools in cotton, we present our new strategies on the characterization of Gossypium germplasm. Based on our experience in a pilot study, we propose a core set of reference DNA markers from each cotton chromosome or linkage group. We also propose a model plant system approach and a large-clone physical map to discover the new genes within the collection. These integrated evaluation strategies would examine DNA profiles of cotton accessions for potentially useful genes, followed with agronomic performance analysis.
Technical Abstract: Many crop germplasm collections have been assembled and evaluated with classical descriptor phenotypes and traits important in crop improvement. While their genetic variation was exploited in the 20th century, access to new variation was limited by phenotypic evaluation. In the 21th century, DNA-based genetic-descriptors are revolutionizing germplasm evaluation, and they are shifting our attention directly toward novel genes or new genotypes. Recent applications of genome mapping confirm that superior genes may be derived from the phenotypically inferior germplasm. As one of the first crop plants to which Mendelian principales were applied, cotton is an important genetic system in collection, evaluation, and utilization of the germplasm. We describe strategies for the molecular characterization of Gossypium germplasm. A core set of DNA markers selected on the basis of the genomic distribution of gene-linked tags and other most polymorphic markers represent each cotton chromosome or workable sets of Gossypium accessions across different gene pools. Accessions with DNA profiles mostly distinct from those of elite cultivars are likely to possess a large number of new genes that lie buried otherwise potentially agronomically useful.