Genetic Analysis Of Sea Island Cotton Resistance To Cotton Fusarium Wilts And Linkage Map Encryption

The building of the high density of genetic linkage map was of great significance for cotton which was an important economic crop.This study was carried out under the result that the construction of genetic map and the preliminary QTL positioning by disease resistance investigation in the field with F2population.In the study,the resistance inheritance of sea island cotton fusarium wilt was studied intensively.What’s more.more markers were used to encrypt the gentic linkage map and further to posite the disease resistance QTL newly by way of the disease resistance survey in the field in later populations on the new encrypted map.The following aspects were mainly included in this research.1.The hybrid group of the disease-resistant sea island cotton06-146and the feeling sick sea island cotton xinhai14was studied to investigate the parents and the descendant of Fi and F2to F2:5.The effect of cotton fusarium wilt on the agronomic character and yield was achieved by significance test.The result showed that the agronomic character of the plant height and branch number was decreased with the increase of the grade of cotton fusarium wilt.Also,the same trend was showed on the index of yield.It also reflected that the fusarium wilt of cotton caused atrophy and the reduction of output.2.The correlation of the yield factor and the role playing in the cotton production was achieved by correlation and principal component analysis.The result showed that the yield of cotton had significant positive correlation with the number of the cotton boll and the weight per plant.Also.the significant negative correlation was showed between the yield and the degree of cotton fusarium wilt. What’s more, the significant negative correlation was showed between the index that had significant positive correlation with the yield.the number of the cotton boll and the plant height.This also reflected that crop failure of cotton caused by the cotton fusarium will.3. The low heritability of the cotton boll and the weight per plant was showed by the heritability analysis.lt was better to select on the later descent. Also, the heritability of pathography was low and it was suitable for the later descent selection. 4.365pairs of premiers were used to screen in the parents.and157pairs of them were gained.And then they were used to screen in its F2descent in order to construct linkage map.And then a map was constructed.it had a distance of872cM,with67markers,a13cM mean genetic distance.The map covered the nine chromosomes of the cotton genome.Also the chromosome of3,5,8,12,16.18.25.26were sited again relative to the previous map.It also confirmed that the correctness of the previous result.The Chr.l was not gained,while the Chr.20was newly sited.The number of linkage group on each chromosome had changed.Such as,the linkage group was one on the foregone map but two in the new one.Also the same in the chromosome16,furthermore,they had the same markers.5. Eight feasible QTLs were detected on the resistance QTL positioning with the software WinQTLCart V2.0by the composite interval mapping method,with the value of LOD2.5.They were sited on the chromosome of3,8,12,16,26, respectively.The contribution rate of the QTL sited on the chromosome3using the F2:5population on the heading stage in Alaer was10.88%,and the value sited on chromosome16using the F2:5population on the period of dry period profile in Alaer and the heading stage in Korla was21.73%、20.25%,respectively.The contribution rate of the QTL sited on the chromosome26and8using the F2:4population on the dry period profile in Korla was69.01%and67.53%,respectively.The value of the QTLs sited on the chromosome12,using the F2:4in Korla on the period of dry period profile and F2:5in Korla on the period of heading stage and dry period profile were61.42%,61.42%and34.33%individually.The QTLs of qFw4,qFw5,qFw6,qFw7were the major gene according to the table4-2.The value of the additive effect of them were negative value.This also illustrated that the synergia allelic genes were come from disease-resistant parents.So the four QTLs had great value in use in molecular marker-assisted breeding.