The Enhancement Effect And Genetic Diversity Of Interspecific Germplasm In Cotton

The germplasm such as wild race, wild species and the cultivars except for Gossypium.hisutum cultivars, have abundant genetic diversities and consequently possess a lot of elite genes which can be utilized in cotton breeding due to the different environment distribution and long period natural selection for these species. They have some potential elite characters including drought-resistance, disease and pest resistance, cold-resistance, seed glandless with plant gland, male sterile, fine fiber finess and high strength etc. Domestic and foreign breeders launched interspecific hybridization among the species of Gossypium for utilizing benefit genes of wild cotton extensively, and have got more than twenty kinds of high generation offspring between wild species and Ghirsutum . A lot of elite germplasm with stable traits have been selected from them, which enlarged the current genetic base of cotton. But these germplasm has just been used very few and has not played the important roll in the application and theory research. Therefore, 155 lines of interspecific crosses between Ghirsutum and other species were collected in our research. The exogenic parents of these germplasm involved three types of cultivars, five types of Ghirsutum races, seven wild species. The exogenic components and genetic diversity of the lines of interspecific crosses between Ghirsutum and other species were identificated with SSR molecular and important agronomic traits analysis. The purpose of this paper was to evaluate the effect of Ghirsutum germplasm enhancement through distant hybridization and select the germplasm which have better value in application, so as to accelerate the application of interspecific crosses in cotton breeding. The results showed as following:1 By evaluating important agronomic traits,we found that different wild species played different rolls on the improvement of Ghirsutum. Ganomalum and Gbarbadense promoted the improvement of fiber length. Ganomalum and Gthurberi were useful for the improvement of the fiber strength, but the effect was not acquired from Gbarbadense and Garboreum. A great progress was achieved by using Gthurberi on the the improvement of fiber qualities abroad. Garboreum and Gsub sp mexicanum had some effect in improvement for salt-tolerance. It is easy to select germplasm with Verticillium wilt resistance among the progenies of interspecific crosses of Ghirsutum with Gsturtianum and Gpurpurascense, but the predominance of Gbarbadense has not been found. Gsturtianum has significant effect in the improvement of Fusarium wilt resistance, but the predominance of Garboreum has not been found. Garboreum and Ghisutum race richmondii played great roll on the breeding for pest-resistance.2 By using exogenic parents as CK, two types of 25 SSR specific alleles were found in 15 SSR loci from 44 pairs of primers tested among interspecific crosses between G hirsutum and other species. One type was the earmark for wild cotton including 9...