| Founder parents have played important roles for the development of wheat in China,which have produced many large-grown varieties or important breeding lines.All founder parents in different crops were found as a result of summation of the pedigrees.How are founder parents produced from various germplasm? Why many important varieties could be bred through using them? The use of Linfen 5064 as the founder parent addressed three problems in the breeding for strong-gluten wheat.The first problem is that quality is negatively correlated with thousand kernel weight(TKW).The second problem is that dwarfness is associated with late maturity.Finally,Linfen 5064 overcomes the need to have the glutenin subunit combination 5+10 for good quality,since it lacks these subunits yet still has good quality.In this study,the plant height,heading date,grain traits and genotypes of Linfen 5064 and its derived cultivars and two DH populations were analyzed to clarify the formation characteristics and genetic rules of Linfen 5064 as a founder parent.QTL mapping for phenotypic traits was conducted to explore the major QTL,which laid a foundation for fine mapping and gene cloning.The main results were as follows:1.Phenotypic traits of founder parent Linfen 5064.Linfen 5064 is an important founder parent for the combination of dwarf and early maturity.With the increase of generations,the plant height of the derived progeny gradually decreased.Plant height decreased by 10.73%from first to third generation.Linfen 5064 could advance the heading time of the first generation by 2.3 d.The yield potential of the derived cultivars of Linfen 5064 is increasing continuously,which can increase the TKW of the first generation by more than 3 g.Grain length decreased with the increase of generations,while grain width and grain thickness increased gradually.2.Important chromosomal loci and regions in founder parent Linfen 5064.32 derived cultivars of Linfen 5064 were analyzed by 90 K SNP.In Linfen 5064,there were 2621 dominant alleles with 100% genetic contribution in all derived generations,accounting for16.47% of the total effective loci.Generally,the genetic contributions of Linfen 5064 to the first,second and third derived generations were 77.03%,72.17% and 67.69%,and the contribution rata decreased significantly along with the increase of generations.A total of 250 regions with high transmission rate to Linfen5064 were found,which were distributed on 21 chromosomes of wheat with a total length of 677.41 Mb(0.10-58.74 Mb).There were 138 regions with associated QTL/ genes.3.Excellent QTL regions for plant height,heading stage and grain traits in Linfen 5064.In the present study,the genetic regions related to plant height,heading date,grain traits from the founder parent Linfen 5064 were analyzed using two haploid(DH)populations.A total of55 stable excellent QTLs were detected in Linfen 5064.Qph-LJ.5A.3 and Qph-LN.5A.2,Qph-LJ.5A.2 and Qph-LN.5A.1,Qph-LJ.2D and Qph-LN.2D,Qgl-LJ.2D.1 and Qgl-LN.2D were detected in both populations which were stable and excellent genome regions controlling plant height and grain length in Linfen 5064.The phenotypic variation rate of 8 QTLs(Qph-LJ.4B.2,Qph-LN.4B,Qhd-LJ.5A.1,Qgw-LJ.6A.3,Qgw-LJ.6A.2,Qgw-LN.4D.1,Qtgw-LJ.6A.1,and Qtgw-LN.4D.1)were greater than 20%,and the allele of Linfen 5064 had the greatest effect on the traits.Therefore,8 QTLs of Linfen 5064 were key genomic regions controlling plant height,heading stage and grain traits.38 excellent QTLs of Linfen 5064 had higher transmission rate in the derived cultivars which were continuously selected and retained in breeding and maybe important and excellent genome regions related of plant height,heading stage and grain traits of founder parent Linfen 5064.4.Excellent QTL regions for spike related traits in Linfen5064.The genetic regions related to field grain number per spike from the founder parent Linfen 5064 were analyzed using a haploid(DH)population developed from a cross between Linfen 5064 and Nongda3338.Thirteen stable QTL explaining 3.91-19.51% of the phenotypic variation were found.The effect of six of these QTL,Qtss.saw-2B.1,Qtss.saw-2B.2,Qtss.saw-3B,Qfss.saw-2B.2,Qbsss.saw-5A.1,and Qgns.saw-1A,were verified by another DH population(Linfen 5064 /Jinmai 47),which showed extreme significance(P<0.05)in more than three environments.No homologues of reported grain number related genes from grass species were found in the physical regions of Qtss.saw-2B.1 and Qtss.saw-3B,indicating both of them are novel QTL,or possess novel related genes.The positive alleles of Qtss.saw-2B.2 from Linfen 5064 has the lager effect on TSS(3.30%,0.62)and has 66.89% percent in Chinese landmark cultivars under selecting.This study revealed three key regions for GNS in Linfen 5064 and provides insights into molecular marker assisted breeding. |
PDF Full Text Request