The Selection Efficiency Of Molecular Markers On Cotton Single Important Traits And Its Influence On Other Agronomic Traits By Using Recurrent Selection Population

Cotton was an important industrial crop. It played a critical role in our national economic development. However, since 1990, a series of problems were arised, For example xotton high yield breed was limted,the development of genetic improvement was slowed on fiber quality and resistance to verticillium wilt. So it was urgent to breed new cotton variety of high yield,elit quality and resistance in order to change the present cotton breeding state.Traditional breeding depended on hybridization with excellent germplasm to pyramid several elite genes into one variety .But it cost lots of time and money, Moreover, the efficiency of selection was low and the development was slow.But,molecular breeding was effective which fully utilized the technology of modern molecular marker.In this paper, the research comprised two aspects:Firstly, By use of the parents:chang96 characterised as a resistant line to verticillium wilt and junmian 1 which was a susceptibile variety. A F2 population was produced to construct molecular linkage map and to tag QTLs,which was as saving to MAS of resistance to Kwilt.Secondly, a recurrent selection populations were to explore the effect of the performance of Bt gene and the major QTL of fiber strength on cotton yield and quality and to study the practical efficieny of MAS by using the SSR1521, RAPDUBC301 markers associated with the major QTL for fiber strength.At the same time, compared to the influence of different selection methods to the yield and fiber quality of cotton. Some conclusions were acquired in following aspects: 1. Constructing of molecualar linkage mapLinkage analysis with th Mapmaker programe resulted in the establishment of 22 linkage groups with 124 loci and other 16 unlinked loci were independent.Twenty-two linkage groups were associated with with 14 chromosomes ,which were 3 , 5 , 6 , 7, 9 , 10, 12, 14, 16, 17, 18, 20 , 22 s 23 of cotton genome and three groups were localized on the A or D subgenome, respectively.Another five linkage groups were not connected with corresponding any chromosome.The linkage map comprised 1128.9cM,or coveringapproximtely 22.6% of the total cotton genome,which was an elementary molecualar linkage map.2. QTL tagging of gene with resistant to verticillium wiltAccording composite interval principle to scan total cotton genome by Mapmaker/QTL programe, one resistance QTL was detected and localized on chr9 between the interval of the marker JESPR114 and NAU462,and explained 13.8% of phenotypic variance in F2 population.3. The efficiency of MAS with major QTL for fiber strengthThe efficiency of MAS was studied through two markers associated with the major QTL for fiber strength. The t test displayed that the selection gained a highly significant difference with the two markers SSR1521 and RAPDUBC301. Another selection arrivedsignificant difference between the genetype + + and--,the same result was gainedbetween the genetype H-- and--.As the two markers were used simultaneously,thedifference of them were extremely significant.The D-value was equivalent to the marker SSR1521,but the D-value was over with the single marker RAPDUBC301.4. The influence of the major QTL for fiber strength to cotton yield ,fiber qualityThe average fiber strength,elongation,micronaire,length and uniformity of plants with the marker were higher than plants with no marker.Among them,fiber strength,elongation and micronaire were extremely significant higher.But no significant changes existed between length and uniformity.Among the factor of consisiting of yield,the average boll size and seed index for plants possing the marker was extremely significant lower than the plants without marker.The lint percentage of plants having marker was higher,but no significant changes existed. Therefore,there was no harmful linkage between fiber strength major QTL and the genes of other agronomic traits. It was obvious that the major fiber strength QTL could improve other traits except micronaire.5. The influence of the insertion of Bt gene to cotton agricultural traitsIt indicated that the boll...