Construction Of High Density Genetic Map For Multi-kernel QTL In Common Wheat-Agropyron Cristatum(L.)Gaertn Derivative Line Pubing3504

Wheat is one of the most important grain crops,but the narrow genetic basis has seriously restricted the high yield,stable yield breeding and product development.Based on the analysis of the evolutionary history and breeding process of wheat,a large number of studies have found that distant hybridization can effectively solve this problem.Grain number per spike is one of three factors of wheat yield,so effectively increasing the grain number per spike plays an important role in the further improvement of wheat yield.Our lab created lots of offspring lines through distant hybridization between common wheat Fukuho(Triticum aestivum,2n=6x=42,AABBDD)and tetraploid Agrppyron cristatum Z559(Agrppyron cristatum(L.)Gaertn.,2n=4x=28,PPPP),including Pubing3504 whose average of grain number per spike reached 102.66 was significantly higher than that of the modern commercial varieties by planted them in 5 ecological areas at 2 years.In order to explore the related genes controlling high grain number per spike and clarify the genetic relationship between high grain number per spike and the P genome,this study used Pubing3504 and its Pubing3504×Jing4839 RIL population as study materials,through the development of new molecular markers and the investigation of the field character in 3 years,the main effect QTL controlling high grain number per spike was mapped in the end of 1AS;It was also found that the QTL and the P genome specific marker CDs29 were co-segregation,so the alien introgression of 1AS results in the high grain number per spike.1.Construction of high density genetic map: According to the A genome sequence of triticum urartu and SNP position information of wheat 90 K chip,we developed 380 pairs of SSR markers and 126 pairs of SNP markers;Polymorphic markers were used to detect RIL population,and a high density genetic linkage map of wheat 1AS was constructed including 30 pairs of SSR markers and 26 pairs of SNP markers2.Mapping of QTL controlling high grain number per spike: Through investigating Kernel number per spikelet,Spikelet number per spike and Grain number per spike of RIL population at 3 years(2012-2013,2013-2014 and 2014-2015),a main effect QTL was mapped in the end of 1AS,between snp26 and snp45 whose genetic distance is 7 cM.Explained variation of Kernel number per spikelet,Spikelet number per spike and Grain number per spike were 15.15%,11.38% and 22.68%,so the QTL was a major QTL.3.Identification of alien introgression of Pubing3504 and molecular marker tracking: we obtained residual heterozygous line from RIL population by 1AS marker detection,and we further obtained NILs only different in the end of 1AS from the residual heterozygous lines;these NILs was used to identify P genome introgression by transcriptome sequencing using young spike at double ridge stage;we found 90 gene sequences specific expression in NIL with Pubing3504 genotype,and these sequences were used to develop markers;we found a gene sequence came from P genome,a specific molecule primer named CDs29 were developed to trace the alien introgression;CDs29 was mapped in main effect QTL.4.Genetic relationship between the high grain number per spike and P genome: the P genome specific marker CDs29,can be divided RILs into two kinds of line,the first kind with 1AS alien introgression(64.14 grain per spike)and the second with no 1AS alien introgression(42.89 grain per spike);The statistical analysis showed that the high grain number per spike of the first kind was significantly higher than that of the second kind;Through the marker CDs29 detecting other common wheat-Agropyron cristatum(L.)Gaertn derivative line Including additional lines(98.89 grain per spike),translocation line(82.27 grain per spike)and introgression line(88.95 grain per spike)with high grain number per spike created in our lab,we found the high grain number per spike and the P genome specific marker CDs29 were co-segregation,so the high grain number per spike came from P genome.5.Analysis of segregation distortion in RIL population: Through 1AS markers detect of RIL population,we found that the number of offspring lines with Pubing3504 genotype in RILs(about 223:336)was significantly higher than the theoretical value of 1/2.Research results show the alien introgression of 1AS may results in segregation distortion in RIL population.The major QTL controlling Kernel number per spikelet,Spikelet number per spike and Grain number per spike and its specific molecular markers can be used to wheat high yield breeding in the future.