Cyto-morphological and RAPD analysis of F1, F2 and BC1 generations of a cross Gossypium arboreum x Gossypium thurberi.

Cytomorphological studies and RAPD analysis was carried out in parents, F, hybrid, F, and BC1 generations of cross between Gossypium arboreum var. MPKV GMS and G. thurberi. Substantial variability for the different morphological characters in the F-2 and BC1 generations was observed. F, hybrid showed chromosome configurations 9.4(I)+8.00(II)+0.08(III)+0.09(IV) indicated sufficient degree of bivalent formation. On an average 8.43(I)+3.77(II)+2.59(III)+0.57(IV) and 8.40(I)+3.69(II)+2.69(III)+0.54(IV) chromosome configurations were observed in F2 and BC, generations, respectively. Very low trivalent (0.50) and (0.34) for quadrivalent indicated the homology between the paired chromosomes and the chances of exchange between chromatid formed two different species. Thus, the inter genomic transfer of desirable genes responsible for pink bollworm (Pectinophora gossypiela Saunders) tolerance and better fibre quality parameters from wild G. thurberi to cultivated G. arboreum is possible. There was considerable variation in the ability of individual primers to detect DNA polymorphism. The OPA 12 showed the creation of priming sites during meiosis of one of the parent leading to the generation of new amplification product in F, and most probably it is from G. thurberi. These unique markers would have originated due to recombination, mutation or random segregation of chromosomes at meiosis during hybrid formation. The F2-2 progeny showed one additional band than F, might be due to reverse recombination event happened in F, plant. Similarly, F2-1 progeny show the recombination event and in F2-5, F2-6, and F2-8 loss of priming site. Sufficient homology observed between A and D chromosomes indicated quite high chances of getting recombinations of pink bollworm tolerance because of repellent scent present in petals of G. thurberi which prevent oviposition of the moth on plant.