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 Printable version |
Cotton improvement through interspecific hybridization |
Cahiers Agricultures. Volume 15, Number 1, 135-43, Janvier-Février 2006 - Le coton, des futurs à construire, Synthèse
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 Résumé
Article gratuit
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Author(s) : Guy Mergeai |
Summary : For more than forty years, investigations have been carried out at the Gembloux Agricultural University, Belgium, to genetically improve the main cultivated cotton species (Gossypium hirsutum L.) through interspecific hybridization. This work has led to the development of one of the largest collection of cotton interspecific hybrids in the world made of 21 bispecific diploids, 12 bispecific triploids, 6 bispecific synthetic allotetraploids, 8 trispecific synthetic allotetraploids, 11 bispecific synthetic allohexaploids, 11 bispecific pentaploids and 13 monosomic alien addition lines involving species of A, B, C, D, E, F and G genomes of genus Gossypium. Cytological analyses were carried out on some of these hybrid genotypes to determine the genetic relationships of the different species involved in their development and to assess the possibility to exploit them in breeding programs. During the first thirty years, the priority of the investigations was to improve the technological quality of the lint (strength, length, fineness and elasticity). Two recurrent selection programs were carried out in collaboration with l’Institut national pour l’étude agronomique au Congo (Ineac) and now the Institut National pour l’Etude et la Recherche Agronomiques (Inera) in the Congo Democratic Republic to develop improved cultivars from G. arboreum L. x G. thurberi Tod. x G. hirsutum trispecific hybrid, and from G. hirsutum x G. anomalum Wawra, G. hirsutum x G. thurberi and G. hirsutum x G. raimondii Ulb. bispecific hybrids. Complementary work in this field was realized to assess the possibility to use a G. hirsutum x G. areysianum Hutch. hybrid to simultaneously improve the strength and the elasticity of the fiber. Over the last ten years, researches have been focused on the improvement of the quality of the seed, by trying to develop upland cotton commercial varieties presenting the glanded-plant and glandless-seed trait of G. sturtianum Wil. and on increasing the resistance of cotton to reniform nematodes (Rotylenchulus reniformis Lind. &\; Oliveira) by exploiting the immunity to this pest presented by G. longicalyx Hutch &\; Lee. A last program concerns the assessment of the possibility to exploit Australian diploid species (C and G genome species) through the development of bi-specific hybrids with G. hirsutum. DNA marker-assisted (RAPD, RFLP, AFLP, SSR) selection methods and in situ hybridization techniques were introduced in these new programs in collaboration with the Centre de coopération internationale en recherche agronomique pour le développement-Département Cultures annuelles (Cirad-CA (Cirad-CA, France). The main achievements of this research work are presented and the prospects of using interspecific hybrids in the future to improve cotton are discussed. |
Keywords : vegetal productions, tools and methods |
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