Construction of Genetic Linkage Map Showing Chromosomal Regions Associated with Some Agronomic Traits in Cotton.

Cotton is the world's leading fiber crop and the second most important oil seed crop. In Egypt, plant breeders have made major contributions to the productivity of this crop\\; however, this has led to decreasing the genetic variation among Egyptian cotton varieties. Enhancing the productivity of cotton could be addressed through improving different agronomic traits including early flowering and maturation. In the present investigation, an interspecific cross (G. barbadense x G. hirsutum) was performed between two genotypes, Giza83 (late flowering) and Deltapine (early flowering) to develop F2 segregating population. Analysis of segregation among the 71 F2 individuals was performed using 3 RAPD, 10 SSR, 6 AFLP primer combinations. Twenty four AFLP primer combinations were used in bulked segregant analysis for flowering time. Linkage analysis and map construction were performed using Map Manager. The map showed 22 linkage groups with 140 markers covered a total length of 1556.7 cM. The average length of linkage groups ranged from 1.4 to 649.5. Single point analysis was used to identify the genomic regions controlling traits for plant height, number of nodes at flowering time, bolling date, days to flowering and number of bolls. In total, 30 significant QTL were identified for the five traits on ten linkage groups, among these 11 QTL for plant height, 8 for number of bolls, 4 QTL for each of days to flowering and bolling date and 3 QTL for number of nodes at flowering time. This work represents the first linkage map for the intercross between Giza83 and Deltapine showing chromosomal regions associated with some agronomic traits.