INTERSPECIFIC HYBRIDIZATION AND SYNTHESIS OF ALLOTETRAPLOID GENOTYPES IN COTTON
Mar 13, 2017

Breeding & Genetic improvement WCRC Breeding-Asia WCRC1
Abstract                                                                         Back to Table of contents

Cotton is an important commercial crop of the world.  It has four cultivated and 41 wild species.  The genes for resistance to various biotic and abiotic stresses along with desirable fibre quality traits exist in the wild species of cotton.  The introgression of useful genes to cultivated types can help to reduce the cost of cultivation, overcome the environmental hazards and improve the fibre quality traits.  In the present study, an embryo culture technique has been followed for hybridising diploid cultivated Gossypium arboreum cv G27 with wild diploid Gossypium thurberi to introgress genes for good fibre strength, and resistance to frost, wilt and bollworms from G. thurberi.  The in-vitro cultures of embryos excised 12 and 15 days after pollination (DAP) were employed to develop whole plants from sexually-mediated interspecific crosses.  The 15 DAP embryos produced more vigorous seedlings than 12 DAP embryos.  The embryo germination and seedling response observed was better on Murashige and Skoog's medium supplemented with Ch (250 mg/1) + IAA (1.5 mg/1) + Kin (0.5 mg/1).  The plant regeneration increased considerably if the plants were kept in the dark for the first 15 days.  After the development of roots and two young leaves the embryo derived plants were transferred to the pots containing sterilised soil mixture.  The seedlings were treated with 0.25% colchicine solution for 12 hours with the help of a cotton plug.  Large seedling mortality was observed after the application of colchicine solution.  The synthesised allotetraploid plants obtained after colchicine treatment showed bigger leaves than diploids.  The allotetraploid possessed pigmented plant body and okra type leaves, whereas G27 has pigmented plant body with broad-lobed leaves and G. thurberi possesses green stem and okra type leaves.

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