Genetic Diversity and Potentialities of Improving Egyptian Cotton through AFLP­ DNA Proffi1ng and Hybridization with Some Imported barbadense Stocks

Abstract

resistant. Such loss of current popular cultivars would cause a temporary disruption in the industry as necessary adjustments were made. Therefore, maintaining genetic diversity among crop genotypes offers a measure of protection against potential losses from crop pests and facilitates the creation of segregating populations from which plants with superior gene combinations can be selected.

At present Egyptian cotton genetic resources are very limited meaning that cotton breeders spould focus their exertion to maintain and expand genetic diversity. Patterns of genetic and geographical variation in the cotton collections need to be analyzed in order to better screen for desirable genes. It may be possible to both increase diversity within regions and achieve greater genetic gains in yield and fiber quality by tapping genetic resources outside one's geographic area. Introgression of genes from feral/exotic cotton and through inter-intra-specific hybridization introgress desirable heritable traits (insect, pathogen, and environmental stress resistance; unique fiber properties; biochemical properties; etc.) from related races into acceptable agronomic genotypes.

Recognition and description of genetic variation is accomplished at both the phenotypic and tJ:le genotypic levels. Pedigree information and traditional breeding studies provide useful information on genetic diversity. The ability to utilize DNA technology, such as molecular markers, provides a more accurate and reliable glimpse into these genetic relationships.

Although molecular markers are not a direct product of quantitative genetics, the explosion o£ interests in their use in plant breeding is large part because of the implementations they have for helping solve problems that are common to quantitative genetics and plant breeding (Dudley, 1997). The availability of molecular markers provides an additional dimension to the use of quantitative genetics in plant breeding. Potential applications of molecular markers include marker-assisted selection, identification of the number of genes controlling quantitati_ve traits, grouping germplasm into related groups, selection of parents and marker-assisted backcrossing.

Increasing the scope of this work will assist in a better understanding of the diversity existing in Gossypium, of the heritable systems of cotton plant, and of the systematics of the genus. The DNA-based studies also have afforded the opportunity to examine genetic relationships across different pools of.........