Toward Developing a Complete Set of Monosomic Alien Addition Lines of Gossypium australe Chromosomes in G. hirsutum

Gossypium australe, a diploid wild species (2n=2x=26, GG) native to Australia, possesses many desirable traits, such as resistance to pest insects (such as aphids and mites) and diseases (Fusarium and Verticillium wilts), but it is very hard to transfer these favorable traits into cultivated upland cotton through conventional gene recombination due to no pairing and crossover between chromosomes of G. australe and G. hirsutum (2n=4x=52, AADD). To transfer favorable genes from Australia diploid wild species into tetraploid cultivated cotton, we report the development and identification of a set of chromosome addition lines hirsutum-australe by the combination of morphological traits, marker-assisted selection and molecular cytogenetic method.

Here the amphiploid (hexaploid F₁, 2n=6x=78) of G. australe and G. hirsutum kindly provided by Curt Brubaker were used as female parents to cross with Upland cotton and obtain pentaploid BC₁F₁ (5x=65) which were backcrossed consecutively to develop a complete set of alien addition lines of G. australe individual chromosome in G. hirsutum. From the above backcrossing progenies, we generated a complete set of chromosome addition lines, of which 10 lines are monosomic additions except chromosomes 1,7 and 13. These chromosome addition lines can be used as efficient bridges to transfer desired genes from G. australe to G. hirsutum, as well as for gene assignment, isolation of chromosome-specific probes, flow sorting and microdissection of chromosome, development of chromosome-specific ‘‘paints’’ of Fluor chrome-labeled DNA fragments, physical mapping, and selective isolation and mapping of cDNAs of a particular chromosome of G. australe.