Cotton research in Uzbekistan: Elite varieties and future of cotton breeding

Annually up to 500 thousand ha of cotton is sown in Uzbekistan with Institute varieties. The development of early-ripening, saltand drought-tolerant, insect and disease resistant cotton varieties with superior fiber quality is the priority of our cotton research program. A negative correlation between favorable traits in cotton and a narrow base of cotton germplasm used in breeding programs made it very difficult for breeders to develop such elite varieties of cotton for different regions. However, conventional breeding methods combined with radioactive mutagenesis have been successfully used to overcome breeding problems and succeed in development of elite, productive and highly adapted cotton varieties for past century. Highly productive and resistant varieties with superior fiber quality such as AN-Bayaut-2, Yulduz, Toshkent6, AN-402, AN-Uzbekiston-4, Sharaf-75, Armugon, Gulbahor, Navbahor, Ilgor Mekhnat, Mekhr, Khazina, Diyor, Zangi-Ota, Durru-gauhar, Dekhqonbob, AN-512U, and AN-513 were developed using conventional breeding methods. Moreover, the development of early leaf defoliating varieties presents a big interest for cotton growers in Uzbekistan. Some early leaf defoliating forms from populations of trigenomic hybrids of G. hirsutum x (G. harknessi x G. trilobum) have been selected. Selected trigenomic hybrid forms have inherited from G. hirsutum fruitfulness and earliness, from G. harknessi -droughtand wilt-resistance and from G. trilobum-early defoliation. These forms are being used to introgress leaf defoliation into the widely used elite varieties of the Institute. Ultra early-ripening lines L-171 and L172 have been developed using interspecific hybridization of G. barbadense and Australian species G. bickii. Detail characterizations and description of some of these varieties and lines will be presented. Development of science and technology to the higher level in particular, appearance of genomics made great promises for cotton breeders to rapidly produce elite cultivars, opening new era in cotton breeding  markerassisted selection (MAS). Modern molecular marker technologies make it possible to quickly and reliably identify chromosomal regions containing genes that control agronomic traits and orchestrate the introduction of these genes into elite cultivars. Marker-assisted selection (MAS) allows the selection of superior genotypes in early generaIntroduction Annually, Uzbekistan produces nearly 3.5 million ton raw cotton. Interest in developing elite cotton varieties with superior fiber quality, resistant to various diseases and agricultural pests, tolerant to multi-adversity environmental stresses, and adapted to various extreme growing conditions within the Republic has always been high since Uzbekistan is the main cotton producing country in the Central Asia region, and the fifth cotton producing country in the world. Moreover, being main cotton fiber supplier for a whole former Soviet Union during more than 70 years (Uzbekistan produced 65% of total raw cotton material for Soviets), Uzbekistan had to accelerate all cotton breeding programs and grow more cotton year to year to cover needs of all Soviet Republics. In the result of this, cotton became monoculture in the agriculture of Uzbekistan and cotton monopoly was established in the Republic. Although cotton monoculture caused a lot of ecological problems (soil exhaustion, accumulation biohazard chemicals in the soils because of extensive use of pesticides, increase of soil salinity, decrease in Aral Sea basin, pollution of drinking waters because of extensive irrigation of cotton plantations and etc.) in the region, science of cotton breeding was highly developed and a lot of productive elite cultivars were created. Currently, many Research Institutes are involved in cotton research investigations in the Republic, and the main focus on cotton breeding programs is improvement of yield, fiber quality and disease and pest tions, accelerating the development of new cotton cultivars with high yield potential and superior fiber quality. Marker assisted selection program of cotton have been developing for decades in our Institute. Several protein and secondary metabolite markers associated with wilt resistance, salt and drought tolerance, fiber quality have been developed and being successfully used to evaluate cotton varieties for traits of interest. Moreover, molecular mapping of agronomically important traits using DNA markers such as RFLP, AFLP, SSR and CAP markers is successfully progressing to accelerate breeding programs. Newly initiated linkage disequilibrium mapping of agronomically important traits from Uzbek cotton germplasm resources is also under way to quickly identify new genes potential to contribute important traits of cotton, accelerating breeding programs in Uzbekistan. Besides, in the Institute the development of transgenic cottons is being successfully carried out. Transformation methods for genotypes of elite cotton varieties of the Institute have been developed and transgenic lines resistant to BASTA have already been obtained.