| Wheat genetic resources and the genetic diversity were the precondition for the wheat varieties improvement. The unique characterization of heredity was formed in different regions during long terms evolution with varied environments and varieties improved breeding objective and the requirement. Assessment the characterization of genetic diversity and introduction of wheat germplasm in different regions are the effective ways to widen the genetic diversity and improve the wheat traits. The effect of breeding objective and directional selection can change the traits of germplasm. Illustrating the factors which affect the genetic diversity will guide breeders to work out breeding schemes and increase the variance of germplasm.In this paper, we analysised the genetic character and variation of wheat germplasm originating from China, Australia, Russia, Netherlands, Mexico and Chile in different aspect including agronomic traits, quality traits, high molecular weight glutenin subunits (HMW-GS) and low molecular weight glutenin subunits (LMW-GS) content. The effect of subunit of HMW-GS and LMW-GS as well as the 1BL/1RS translocation lines to wheat quality were also discussed. The main results are as follows.1. There were obvious differences between wheat germplasms in different regions. The wheat accessions from China and Australia had the traits of short growth periods, reduced plant height and spikelet number per spike, increased grain weight and sterile spikelet number per spike, except that Chinese wheat had the wide flag leaf and short gluten stability time while Australia ones had the narrow flag leaf and long gluten stability time. The wheat germplasm from Russia had the traits of longer growth periods and higher plant height, increased spikelet number per spike, narrow flag leaves, decreased grain number per spike and grain weight and protein content, longer gluten stability time. The wheat accessions from Netherlands had the longer growth periods and increased spike number per plant and gluten stability time, decreased plant height as well as spikelet number per spike and grain weight. The wheat germplasm form Chile had the traits of longer growth periods, increased values in plant height, spike number per plant, leaf area, grain number, spikelet number, protein content and gluten content, flour stability time.2. There were significant differences between the numbers and types of subunits of HMW-GS and LMW-GS in different regions. The mean variant index of 22 traits from 6 countries was as follows: China (1.968) > Mexico (1.963) > Russia (1.914) > Chile (1.901)>Austria (1.899) >Netherlands (1.861). The cluster analysis indicated that the genetic diversity between regions was wide than within regions. The Chinese wheat germplasm had the 3, 9, 5, 5 and 7 alleles in Glu-A1, Glu-B1, Glu-D1, Glu-A3 and Glu-B3 gene locus, respectively. The predominantly subunits were 1, 7+8, 2+12, GluA3a, GluA3d and GluB3j. The subunits 1, 14+15 and 7+8 had the higher frequency and the positive effect to quality traits. The Australia accessions had the 3, 7, 3, 5 and 6 alleles and the predominately subunits were 1, 7+8, 2+12, GluA3c and GluB3b. The subunits 1, 17+18, 7+8 and GluB3b had the higher frequency and positive effect to quality traits. The Russia accessions had the 3, 6, 4, 5 and 6 alleles and the predominately subunits were 1, 7+9, 5+10, GluA3f and GluB3g. The subunits5+10, GluA3f, GluB3b and GluB3g had the higher frequency and positive effect to quality traits. The Netherlands accessions had the 3, 7, 2, 5 and 6 alleles and the predominately subunits were N, 7+9, 5+10, GluA3c and GluB3g. The subunits 5+10, GluA3f, GluB3f and GluB3g had the higher frequency and positive effect to quality traits. The Mexico wheat germplasm had the 3, 6, 4, 5 and 6 alleles in Glu-A1, Glu-B1, Glu-D1, Glu-A3 and Glu-B3 gene locus, respectively. The predominantly subunits were 1, 7+9, 5+10, GluA3d and GluB3j. The subunits 1, 5+10 and GluB3f had the higher frequency and the positive effect to quality traits. The Chile accessions had the 3, 7, 2, 5 and 6 alleles and the predominately subunits were N, 1, 17+18, 2+12, GluA3d and GluB3g .The subunits 17+18, GluA3f and GluB3g had the higher frequency and positive effect to quality traits.3. There were significant different in alleles on locus to quality traits. The major positive effect to quality traits were subunits 1, 17+18, 7+8, 14+15, 5+10, GluA3f, GluA3c, GluB3g, GluB3f and GluB3b, while the minor positive effect to quality traits were 6+8, 13+16, 2.2+12, GluA3a and GluB3j. HMW-GS combination of (1, 17+18, 2+12), (1, 17+18, 5+10) and LMW-GS combination of (GluA3c, GluB3g), (GluA3d, GluB3g), and (GluA3f, GluB3b) had the better positive effect to quality traits than others. The varieties with the subunits combinations of (N, 14+15, 2+12) or (GluA3b, GluB3j) had the bad quality traits. The accessions with the HMW-GS and LMW-GS subunits combinations of (1, 7+8, 5+10, 2+12, GluA3d ,GluB3d) or (1, 7+9, 5+10, GluA3c, GluB3f) or (1, 7+9, 5+10, GluA3c, GluB3g) or (2~*, 7+9, 2+12, GluA3c, GluB3j) or (1, 17+18, 5+10, GluA3c, GluB3j) had the better quality traits. While the accessions with the subunit combinations of (1, 7+9, 5+10, GluA3b, GluB3d) or (2~*, 7+9, 5+10, GluA3f, GluB3j) or (2~*, 7+9, 5+10, GluA3f, GluB3g) had the bad quality traits.4. The gluten content and dough stability time were significantly decreased in 1BL/1RS translocation lines. The subunit to quality traits was different obviously between 1BL/1RS translocation lines and non-translocation lines. Comparatively speaking, 2~* subunit has the positive effect to protein content in 1BL/1RS translocation lines compare to non-translocation line as well as 17+18 subunit to wet gluten content, 7+9 subunit to wet gluten content and dough stability time, GluA3b subunit to dough stability time, GluA3c and GluA3f subunits to quality. While subunit 1 has the negative effect to dough stability time in 1BL/1RS non-translocation lines comparing to 1BL/1RS translocation lines as well as GluA3b to protein content and wet gluten content. In general, the subunit had the positive effect to quality traits in 1BL/1RS non-translocation lines.5. Developing with the improved varieties, the wheat accessions from the Huanghuai Wheat Region of China had the characters of increasing tendency of flag leaves width, spikelet number per spike, sterile spikelet per spike, grain number, 1000–kernel weight, grain weight per spike and grain weight per plant. There had been significant decreases in plant height, the fist internode length, flag leaf length, spike number per plant. There had the decreasing-increasing tendency of growth periods days, flag leaf area, spike length, protein content, and wet gluten content. No tendency was detected on the traits of agronomic character, quality, disease resistant diversity index and allele number of subunit between HMW-GS and LMW-GS. A novel HMW-GS combination 20/8 was identified in GluB-1 of Chinese landrace Heputou. |
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