| Cotton is an important cash crop in the world. The improvement of cotton fiberquality is becoming extremely significant with the innovation of spinning technology.Although more and more QTL for fiber quality related traits have been developed, theaccuracy and validity of these QTL are not always effective in different populations, fordifferent traits, or by different method of data analysis. It is very important to obtain thereal and effective QTL, which would provide great significance for map cloning andmolecular marker assisted selection. In the present study, the main concepts were shown asfollows:(1) QTL for fiber quality related traits were tested by the first advance backcrossBC4F2segregating population derived from the cross of TM-1, a genetic standard line ofupland cotton, and Yumian1, a high quality cotton cultivar. Subsequently, these QTL forfiber quality traits were identified by the second BC4F2segregating population derivedfrom the cross of TM-1and Acala SJ.(2) BC1population with95plants from a crossbetween Gossypium hirsutum cv. CRI8and G. barbadense cv. Pima90-53was employed toreconstruct genetic linkage map by519SSRs,2CISPs and156Apo I/Taq I selectiveprimer combinations. Then, QTL for fiber quality traits was recalculated by compositeinterval mapping (CIM).(3) In order to excavate the “consensus” QTL and QTL “hotregion” in these independent experiments, QTLQTL for fiber quality traits in cotton，collected from different publications,were used to construct new QTL integrated map usingbioinformation and meta-analysis methods with BC1map as refrence.The main results were summarized as follows：1. In total,3,980SSR primers,238pairs SRAP and85pairs TRAP were used to screenthe polymorphism among Yumian1and T586，and288polymorphic primer pairs wereobtained, acconting for5.32%of the tatal primer pairs. The polymorphic primer pairsproduced119loci when they were used to genotype the158BC4F2individuals of[(TM-1×Yumian1)×TM-1]. One hundred ninteen loci were used to construct geneticlinkage groups with LOD value of8.0and maximum distance of50.0cM. The mapcomprised of119marker loci mapped into26linkage groups withan average distancebetween adjacent markers of5.5cM and covered654.1cM. Twenty-three of26linkage groups were assigned to14chromosomes and3unknown linkage groups.Based on the newly constructed genetic map of tetraploid cotton, QTL for fiber qualitytraits were identified to use composite interval mapping (CIM) method by phenotypic data from BC4F2population, BC4F2:3and BC4F2:4family lines. Thirty-one QTL forfiber quality traits were detected on5chromosomes. Six QTL for fiber elongationwere identified, explaining17.77%-24.70%of the phenotypic variance. Seven QTLfor fiber length were identified, explaining14.01%-24.67%of the phenotypic variance.One QTL for length uniformity were identified, explaining22.9%of the phenotypicvariance. Four QTL for micronaire were identified, explaining22.57%-24.19%of thephenotypic variance. Five QTL for strength were identified explaining20.43%-36.66%of the phenotypic variance. Three QTL for maturity were identifiedexplaining23.65%-24.65%of the phenotypic variance. Five QTL for short fiber indexwere identified explaining22.32%-24.37%of the phenotypic variance. These QTLwere validated by BC4F2segregating population derived from the cross of TM-1, andAcala SJ. The QTL mapped results indicated:1QTL for fiber strength as major QTLwas tested with a same interval (NAU5379-NAU1125) on chromosome24, explaining20.14%of the phenotypic variance.2. A total of358of1980SSR primers scaned polymorphism between CRI8andPima90-53, acconting for18.08%of the tatal primers. The rest358polymorphicprimer pairs amplified370loci. A total of579loci were used to reconstruct geneticlinkage groups with LOD value of4.0and maximum distance of50.0cM. A χ2-test forthe579SSR loci shown120loci (20.72%) deviated from the Mendel ratio (1:1).579marker loci mapped into56linkage groups with an average distance between adjacentmarkers of7.2cM and covered4168.72cM. The length of linkage groups rangedfrom1.25to255.79cM and the markers on the groups ranged from two to44.Forty-three of56linkage groups were assigned to26chromosomes and13unknownlinkage groups. Based on the reconstructed genetic map of tetraploid cotton, QTL forfiber quality traits were tested to employ composite interval mapping (CIM) methodby phenotypic data from BC1population and BC1F2family lines. Forty-seven QTL forfiber quality traits were detected on18chromosomes. Six QTL for fiber elongationwere identified, explaining8.91%-23.73%%of the phenotypic variance. Eight QTLfor fiber length were identified, explaining9.33%-22.58%of the phenotypic variance.Nine QTL for length uniformity were identified, explaining8.35-20.85%of thephenotypic variance. Fourteen QTL for micronaire were identified, explaining7.72%-20.94%of the phenotypic variance. Ten QTL for strength were identifiedexplaining10.44%-16.55%of the phenotypic variance. qFS9-1and qFS9-2weredetected with a same marker interval on A9chromosome in two environments (atBaoding and Xinji in2008)，explaining15.71%and14.42%of the phenotypicvariance. qFU5-1and qFU5-2were detected with a same marker (NAU3828) on A5chromosome in two environments (at Baoding and Xinji in2008). qFS14-1were detected with a TDF marker (TCG/GTT-272). Among the47QTLdetected,27alleles additive effects that decreased fiber quality traits were offered byCRI8, and furthermore,16alleles with positive additive effects and4alleles withnegative additive effects that increased fiber quality traits were offered by Pima90-53.These QTL were validated by BC1and F2segregating population derived from thecross of Han208, and Pima90-53. The QTL mapped results indicated: one QTL forfiber strength as major QTL was tested with a same interval (NAU2395-NAU1092) onchromosome9.3. The ninty-two QTL for fiber quality traits in cotton, collected from differentpopulations (BC1and BC1F2), were used to construct QTL integrated map usingbioinformation and meta-analysis methods with BC1map as refrence. The fivehundred ninty-nine marker loci mapped into26chromosomes with an average distancebetween adjacent markers of5.96cM and covered3571.9cM. Sixty-three QTL wereintegrated into refrence map. The twelve QTL for fiber length were detected on1,7,11,14,16,21and22chromosomes, respectively. The ninteen QTL for micronairewere detected on1,5,7,12,14,16and24chromosomes, respectively. The seven QTLfor fiber elongation were detected on1,9,13,19and24chromosomes, respectively.The fourteen QTL for fiber strength were detected on3,5,9,14,16,18,20and22chromosomes, respectively. The eleven QTL for fiber uniformity were detected on5,9,11,16,18,20and21chromosomes, respectively. The thirty MQTL were mapped on15chromosomes by meta-analysis method. The major MQTL9-1, located at62.16cMon chromosome9could explain17.16%of phenotypic variance to5fiber strengthtraits derived from two populations, confidence interval from45.7cM to63.1cM. Themajor MQTL16-1, located at29.92cM on c16could average explain12.28%ofphenotypic variance to10fiber traits derived from two populations, confidenceinterval from45.7cM to63.1cM. Two major MQTL18-1and MQTL24-2weremapped on chromosome18and24, respectively. The integration of research resultsfrom the same QTL, confidence interval was less than10cM, and the contribution rateis greater than10%. The other MQTL called minor-effect QTL, because confidenceinterval was more than20cM. |
PDF Full Text Request