In a previous phylogenetic analyses of Gossypium based on cpDNA restriction site variation (Wendel & Albert, 1992) an unexpected association of one population of G. aridum from Colima (Mexico) with the accessions of G. davidsonii and G. klotzschianum was observed, indicating the existence of cytoplasmic introgression in the Colima’s population. The two latter species are from Baja California and Galapagos Islands respectively, while G. aridum is distributed in western Mexico, very distant from the Baja California and Galapagos Islands. Morphologically G. davidsonii and G. klotzschianum are very similar (i.e.: shrubby habit, rotate corollas, and large laciniate or dentate involucral bracts) and both together represent the subsect. Integrifolia (sect. Houzingenia). In contrast, G. aridum, as well as G. lobatum, G. laxum, and G. schwendimanii, all of them belonging to the subsect. Erioxylum (sect. Erioxylum), presents arborescent habit, funnelform corollas, and scale-like entire involucral bracts.
To assess the genomic introgression in G. aridum and its relatives we are carrying out an analysis of AFLP markers including a total of 147 individuals from 58 populations of G. aridum, G. davidsonii, G. klotzschianum, G. lobatum, G. laxum, and G. schwendimanii.
We are using EcoRI and MseI as restriction enzymes to digest the total DNA from every individual. Adaptors for the ligations, primers for the PCR, and reactions conditions are described in Wendel’s lab protocols. A total of 8 primer combinations (i.e.: Eco+AGC/Mse+CAA, Eco+ACG/Mse+CAA, Eco+AGC/Mse+CAC, Eco+ACG/Mse+CAC, Eco+AAC/Mse+CAA, Eco+ACA/Mse+CAA, Eco+AAC/Mse+CAC, and Eco+ACA/Mse+CAC) are yielding between 75-50 markers per combination, expecting a total of 400 to 600 markers.