*3.4. Construction and Characterization of Intra Specific Linkage Map*

Among the 1450 SSR primer pairs tested on parental lines, 175 markers were found to be polymorphic. These markers were applied on population. Using a LOD score > 3.0, these markers were assigned to 26 chromosomes for population based on the information on the cotton SSR map [47]. The linkage map was constructed for the F2 population. Each linkage group was assigned to specific chromosome (Figure 4). The linkage maps covered approximately 4402.7 cm (Table 5) with an average distance of 20 cm within the markers which, according to the position of SSR markers, is common with the cotton map [48]. We estimate that we surveyed close to 70% of the cotton map, comparing the length of our map with that of the cotton map. The genetic map for the population was generated by MAPMAKER/version 3.0. Genotypic frequencies deviation from the expected segregation ratio of 1:2:1 for the co-dominant locus or 3:1 for the dominant locus was detected with the legitimacy of the additive-dominance model by means of the Chi square (χ2) method [49].

**Figure 4.** Linkage map and QTLs for heat stress tolerance determined in an F2 population made from cross among Intraspecific MNH-886 and MNH-814 (*G. hirsutum*). The gap indicates that the linkage distance of the primer loci > 50 (cm) indicate significant QTLs (Kosambi).


**Table 5.** Basic characteristics of the genetic map.
