| Wheat(Triticum aestivum L.)is one of the major food crops in the world and has a vital role in food security in our country and in the world.It plays a key role in agricultural production,Seed quality is an important guarantee for agricultural production,it directly affects the effectiveness of agricultural production.Seed vigor is one of the indicators to measure seed quality,which affects the quality of seeding and emergence.Tamyb10-1 gene has an important effect on the seed vigor of wheat,it is very important to study and explore its allelic variation to improve the seed vigor of wheat in China.QTL mapping and association analysis is an important method to study the quantitative traits of wheat.In this study,the characteristics and allelic variation of Tamyb10-1 gene were studied by using the germplasm resources of Huanghuai wheat area and some Landraces and the Aegilops tauschii accessions collected from all over the country.The QTLs of wheat seed vigor related traits were mapped with two recombinant inbred line(RIL)populations of PC and UP.Based on the natural population of 163 wheat cultivars,the association analysis was conducted to the genetic traits related wheat seed vigor by 90 K SNP chip.The molecular mechanism of wheat seed vigor was clarified to provide theoretical basis and gene resources for further improved wheat variety selection,and to provide reference for molecular assisted selection.The main results were as follows:1.The allelic variation of Tamyb10-1 gene and its relationship with grain color were studied in 582 Chinese bread wheat cultivars.The results showed that there were 313 cultivars with Tamyb10-A1a(Chinese spring type)and 269 cultivars with Tamyb10-A1 b in Tamyb10-A1 locus,accounting for 53.8% and 46.2% respectively in 582 Chinese wheat cultivars.There were 564 cultivars with Tamyb10-B1 a and 13 cultivars with Tamyb10-B1 b,accounting for 96.9% and 2.2%,respectively,and novel Tamyb10-B1 alleles were discovered in five materials in Tamyb10-B1 locus.In Tamyb10-D1 locus there were 417 cultivars with Tamyb10-D1 a,and 165 cultivars with Tamyb10-D1 b,accounting for 71.6% and 28.4%,respectively.In the study of the relationship between the Tamyb10-1 gene and the grain color,a total of 8 genotype combination were found in 582 bread wheat cultivars.The grain color with Tamyb10-A1 a / Tamyb10-B1 a / Tamyb10-D1 a genotype combination was white,and the other seven genotype combinations were red.2.A total of 194 Chinese cultivars were planted in 2011-2012 and 2013 – 2013 cropping seasons and 368 wheat materials including landraces,historic cultivars and currently popular cultivars were planted in 2013-2014 cropping seasons,which were used for the germination experiment.The traits of seed vigor were calculated.The results indicated that for the grains in the period of dormancy the germination percentage(GP)of the grains was not significantly different,but the germination index(GI)and the 2nd-day germination percentage were significantly different.The genotype combination of Tamyb10-A1a/Tamyb10-B1a/Tamyb10-D1a(white grain)had the highest germination value,and then the genotype combination of Tamyb10-A1b/Tamyb10-B1a/Tamyb10-D1 a and Tamyb10-A1a/Tamyb10-B1 a / Tamyb10-D1 b.The genotype combinations with two mutant loci were the smallest germination value,and significantly different with the wild genotype,indicating that the genotype of grain was more deeply dormant and less prone to sprouting.For the grains with breaking dormancy the germination percentage(GP)and the germination index(GI)of five genotype combinations with red grain were significantly higher than those of the genotype combination with white grain(Tamyb10-A1a/Tamyb10-B1a/Tamyb10-D1a),the genotype combination of Tamyb-A1b/Tamyb-B1b/Tamyb-D1 b had the highest 1st-day germination percentage,while the genotype combination of Tamyb-A1a/Tamyb-B1a/ Tamyb-D1 a with white grain had the lowest germination percentage.3.The allelic variation of Tamyb10-D1 in Aegilops tauschii was studied by using 110 materials from all over the country.The results showed that there were three novel allelic mutants cloned which not in bread wheat cultivars,named Tamyb10-D1 c,Tamyb10-D1 d and Tamyb10-D1 e,respectively.And two pairs of co-dominant markers(T3D-3 and T3D-4)capable of identifying these three allelic variants were designed.There were 40 materials with Tamyb10-D1 c gene identified by marker T3D-3,and 60 materials with Tamyb10-D1 d gene and 9 materials with Tamyb10-D1 e gene by marker T3D-4 in the surveyed 110 Aegilops tauschii accessions.4.QTL mapping and QTL epistasis analysis were carried out in two recombinant inbred lines(RIL)populations of PC and UP,which were planted in Zhengzhou and Anyang,respectively.Eight QTLs were found in the single additive QTL analysis with threshold of LOD ? 2.5 in the PC population.The LOD ranges of these QTLs were 2.6-4.7,and the phenotypic contribution rate was 10.2-14.8%,which was located at 1B,1D,2D,4B,6D chromosomes.Two epistatic QTLs were found in the QTL epistatic analysis.The LOD values were 5.7 and 5.5,and the phenotypic contribution rates were 14.8% and 31.2%,respectively.There would be a epistatic QTL with an important effect on the phenotype.In the multi-environment QTL analysis,10 additive QTLs were found in four traits of seed vigor and two environments.The range of LOD was 2.9-4.8 and that of the phenotypic contribution rate was 6.2-11.5%.Six additive QTLs were found in the UP population,the range of LOD was 2.5-91.9,and that of the phenotypic contribution rate was 0.1-18.0%.Six QTLs distributed in 1D,3B and 5B chromosome.The LOD value of QTL on 3B chromosome was 91.9,and the phenotypic contribution rate was 18%,which was a major QTL.The QTL affected germination percentage and germinability simultaneously.Many epistatic QTLs were found in the epistatic analysis,but the phenotypic contribution rates of these QTLs were small,indicating that epistatic interaction had little effect on germination value.There were 19 QTLs in the multi-environment additive QTL analysis.The LOD value of these loci ranged from 2.7 to 90.3,and the phenotypic contribution rate range was 0.3-25.3%.5.Genome wide association analysis was carried out using TASSEL software for the traits of seed vigor based on 90 K SNP chip in natural populations of 163 Chinese bread wheat.The results indicated that the five SNPs were closely related to the germination percentage,The SNPs of these loci were located on 1A,2B(2 SNPs),5A and 5B chromosomes,respectively.The contribution rate of these sites was 17.7-21.8%.Further analysis showed that there was no linkage disequilibrium in the five loci,but the germination percentages of these genotypes was significantly different. |
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