Mapping Of Thousand-Grain-Weight Genetic Loci In Wheat And The Effect Of Dwarfing Genes On Plant Shape

The plant type of wheat is closely related to the wheat yield.The ideal wheat plant type can better serve the production and increase the wheat yield.The plant height is one of the main factors that affect the plant type of wheat and thus the yield.Studies have shown that appropriately reducing the plant height can effectively enhance the lodging resistance of wheat,thereby increasing the yield of wheat.Thousand-grain-weight is one of the indicators to measure wheat yield.Effective research on thousand-grain-weight is of great significance to improve wheat yield.Based on the previous research,this paper uses the recombinant inbred line population（F₈）derived from Zhou 8425B×Xiaoyan 81 and 479 wheat materials collected in the laboratory from home and abroad.The genetic map performed QTL mapping for thousand-grain-weight,grain length,grain width and grain thickness in the three environments.Cluster analysis was carried out according to the location results to determine the dominant groups in the germplasm materials of Shaanxi,Henan and Shandong in the Huanghuai wheat area.Provides genotype reference for molecular assisted breeding.At the same time,KASP markers were used to identify the natural population materials,and the plant height traits obtained from multiple points over many years were analyzed.The main results are as follows:Through QTL mapping,a total of 22 QTLs on 8 chromosomes were detected,the variation explanation rate（PVE）ranged from 4.77%to 19.95%,and 12 loci were major QTLs（PVE>10%）.Among them,Qkgw.nwafu-6B is a new QTL.QTLs at chromosomes 4A,6A,6B,and 7D were detected in multiple settings,where QTLs at chromosomes 4A and 7D were located at the same or close to the reported relevant loci.The QTL on chromosome 6A is located in the exchange cold spot area of wheat.According to the results of KASP and cluster analysis,there are different groups on chromosome 6A,which may be new QTL loci.A KASP marker co-segregated with Qkgw.nwafu-6B was developed with reference to the RIL population mapping results,and it was proved that this locus was significantly associated with the 1000-grain weight phenotype in 479 natural population significance tests.Cluster analysis was performed on the identified major QTL intervals based on 106 wheat materials in Huanghuai wheat area,and four groups with at least 20%frequency in different production intervals were found.One major site,Qkgw.nwafu-6B,was detected,which was a new QTL,and a molecular marker KASP＿IWA349,which was co-segregated with this QTL,was developed.Through the statistics of wheat plant height after molecular marker detection,it can be clearly seen that the dwarf gene has a significant effect on reducing wheat plant height and increasing wheat 1000-grain weight.By comparing the distribution frequencies of the three dwarf genes in Shaanxi,Henan,Shandong,Shanxi and Jiangsu provinces in the Huanghuai wheat area,it can be arranged that Rht24（90.83%）is higher than Rht-D1b（63.33%）higher than Rht-B1b（23.33%）.The distribution frequency of Rht24 was the highest,but the single culm reduction effect was not prominent.After interacting with Rht-B1b and Rht-D1b,the culm reduction effect could reach 19.6%,and the 1000-grain weight increased by 7.3%.The Rht-B1b gene in Shaanxi has a high distribution,and most of the other provinces appear in its wild type,which may be related to the fact that the main popular variety in Shaanxi is Xiaoyan6 containing Rht-B1b.On the whole,it can be seen that different dwarf genes Rht-B1b,Rht-D1b and Rht24 have obvious preferences in the utilization,which may be related to the breeding goals such as climate and disease resistance in different provinces and production areas,as well as most materials.The selected dwarf source is relevant.