Development And Evaluation Of Introgression Lines From Gosspium Hirsutum Race Latifolium ACC TX-34 In G. Hirsutum ACC TM-1

Cotton（Gossypium spp.）is an important commercial crop,which contains four cultivated species.Upland cotton,Gossypium hirsutum as one of the four cultivated species,dominates the world’s cotton fiberproduction accounting for approximately 90%of the total production.With long and extensive selection and improvement,current upland cotton cultivars showed high yield or resistant to diseases,however,which also lead to narrow genetic base and low genetic diversity.Primitives or landraces of cultivated species,such as G.hrisutum race latifolium native to the central America,possess invaluable characteristics unavailable in the cultivated cotton gene pool,such as high fiber quality,resistances to diseases or tolerance to drought,which are extremely useful for the improvement of tetraploid（G.hirsutum）cotton.Here,G.hirsutum race latifolium acc TX-34 was employed to introgress durable traits into a common recipient,Texas Marker-1（TM-1）,a genetic standard for future breeding.AB-QTL model was used for QTL mapping.The main results were as follows:Total of 285 markers found to be polymorphic between parents were then used to survey BC1（96）mapping populations.A total of 221 loci mapped in the genetic map which had 33 linkage groups.There were 18 groups with 142 loci in A-subgenome with full length 879.2 cM and average distance 6.2 cM.There were 15 groups with 79 loci in D-subgenome with full length 622.6 cM and average distance 7.9 cM.The total length of the map was 1501.8 cM,covering 32.23%of the cotton genome.One hundred and forty-nine chromosome segment introgression lines（CSILs）were developed.The length of the CSILs segments covered 28.82%of the whole cotton genome,ranged from 0.1 to 54.5cM and the averge length was 6.4cM.The number of the segments in CSILs ranged from 4 to 31 and the average was 17.3.QTL IciMapping 4.0 software was used to analyze on the data of yield and fiber related traits of the BC₃F₂ and BC₃F_2:3 populations.We found that 22 QTLs were associated with boll weight（BW）,lint percent（LP）,seed index（SI）,lint index（LI）,fiber length（FL）,fiber micronaire value（MV）and fiber elongation（FE）.Three QTLs for BW,5 QTLs for LP,3 QTLs for SI,1 QTL for LI,4 QTLs for FL,4 QTLs for FE and 2 QTLs for MV were mapped with the LOD>2.5 threshold.Total of 12 elite germplasms,including bigger boll size,high lint percentage,longer fiber or stronger fiber,were developed for future breeding.