Characterization Of High-and Low-molecular-weight Glutenins From Xinjiang Wheat Landraces And Cultivars In Spring And Winter Wheat

Glutenins are one of the important storage proteins in the endosperms of wheat grains.They play a key role in determining the quality of wheat flours.Glutenins are further divided into high molecular weight glutenin subunits（HMW-GS）and low molecular weight glutenin subunits（LMW-GS）relying on their molecular weights and other biochemical characters.It is well known that the types and the numbers of functional glutenins have a profound influence on the baking quality of wheat flours.Xinjiang has a special character in geography,climate and soil type,and also near the diversity center of wheat and its relatives in Central and Southwest Asia,which has rich wheat germplasm resources.There are plenty of excellent genes/traits in Xinjiang wheat germplasms need to further exploited and utilized.For better understaning the genetic diversity of glutenin loci of Xinjiang wheat resources,we used SDS-PAGE and allele specific molecular markers to identify the HMW-GS and LMW-GS combinations in 300Xinjiang wheat landraces and 43 cultivars in spring and winter wheat.Additionally,the LMW-GS genes at the Glu-A3 of 18 landraces of spring and winter wheats were cloned and sequenced.The main results were as follows:1.A total of 26 HMW-GS combinations were identified in 300 Xinjiang wheat landraces and 43 cultivars,of which 18 combinations each was identified from landraces and cultivars.Combinations null,7+8,2+12 is the predominant combinations of the landraces and cutivars,accounting for 63.3%（190/300）and 39.5%（17/43）respectively.Three（null,1 and 2^*）,nine（7+8,7+9,6+8,17+18,14+15,20,7,8 and6^x+8^y）,and seven alleles(2+12,5+10,2.1+10.1,2.6+12,5^**+10,2+12^*and 4+12)were respectively identified from the Glu-A3,Glu-B3 and Glu-D3 loci,of which alleles null at Glu-A1,7+8 at Glu-B1 and 2+12 at Glu-D1 being the predominant type and accounting for 90.4%,86.3%,and 70.3%of the 343 Xinjiang wheats at each loci.One novel subunit,6^x+8^y,and three rare subunits,namely,2.1+10.1,5^**+10,and 2+12^*were identified from Xinjiang wheats.A pair of subunit 2.6+12,which was unique to the Glu-D1 locus of Xinjiang winter wheat,was the second predominat pairs of the total winter wheat landraces.The frequency of this subunit pairs was 46.5%.2.A total of 58 LMW-GS combinations were identified using 7,10 and 5 allele specific markers unique to Glu-A3,Glu-B3 and Glu-D3 in 343 Xinjiang wheat,of which44 and 24 combintions were identified from landraces and cultivars.Eight alleles namely,a,b,c,d,e,f,new1 and new2,and nine alleles,viz.a,b,c,d,g,h,i,new3 and new4,were respectively identified from the Glu-A3 and Glu-B3 loci,of which alleles Glu-A3c and Glu-B3i,consisting 44.9%（154/343）and 39.9%（137/343）of the total Xinjiang wheats,were found to have highest frequency at the Glu-A3 and Glu-B3.A total of seven gene haplotypes was identified from the two genes belonged to Glu-D3,with five haplotypes,namely,Glu-D3-21,22,23,new5,and new6,and two haplotypes,Glu-D3-31 and 32,being identified from the genes of Glu-D3-2 and Glu-D3-3.Of them,Glu-D3-21 and Glu-D3-31 were the predominant haplotypes for Glu-D3-2 and Glu-D3-3,and their frequency were 85.1%（292/343）and 93.9%（322/343）,respectively.Six novel types,namely,Glu-A3new1,A3new2,B3new3,B3new4,D3new5 and D3new6,were identified from Xinjiang wheats.The Glu-A3new1 was negative to any of the seven markers specific to Glu-A3,but Glu-A3new2 amplified a larger（about1100bp）DNA band for marker Ad than expected 967bp.Similarly,Glu-B3new3 was negative to any of the 10 markers of Glu-B3 except for Bbef,whereas no DNA band was amplified for Glu-B3new4 with all Glu-B3 primers.On the other side,Glu-D3new5was positive to both the primers of D21/22 and D23,but Glu-D3new6 was negative to all the 3 pairs of Glu-D3-2 primers.3.Three primers were used to amplify LMW-GS genes of Glu-A3 from 18Xinjiang landraces in winter and spring wheat.As expected,DNA bands were amplified mostly accessions.No positive clones was identified from the ligated DNA products amplified by primer GluA3-1,and no LMW-GS sequence was verified from the DNA bands amplified by GluA3-3.A total of 33 LMW-GS sequences was verified from the DNA bands amplified from the 12 of the total 18 accessions of landraces in spring and winter wheat using GluA3-2.Of the 33 LMW-GS sequences,13 were predicated to be active genes,which could be encode a normal proteins.Eleven different sequences were obtained after exclude the sequences with 100%similarity from different accessions.All of the 11 sequences were classified as LMW-m types because of the first amino acid resiude at the N-terminal was methionine.The 11 sequences were divided into three types,namely Sig-1,Sig-2 and Sig-3,according to the 10th and 12th amino acids in the signal peptide being leucine/isoleucine（L/I）,histidine/valine（H/V）,and leucine/valine（L/V）,respectively.Similarly,these genes also divided into 3 types of N-1,N-2 and N-3,with the 5th and 12th amino acids in the N-terminal were cysteine/glutamine（C/Q）,tyrosine/proline（Y/P）,and cysteine/proline（C/P）,respectively.Not expectedly,two N-2type aminophenol sequences of DM1877-1 and DM1881-3,contained only 7 cysteines and was short of one cysteine with the normal LMW-GS.