Variation in the HMW and LMW glutenin subunits from Spanish accessions of emmer wheat (Triticum turgidum ssp. dicoccum Schrank)

Emmer wheat (Triticum turgidum ssp. dicoccum Schrank) is hulled wheat that survives in marginal areas of the Mediterranean Region. The HMW and LMW glutenin subunit composition of 97 accessions of emmer wheat from Spain have been analysed by SDS-PAGE. For the HMW glutenin subunits, four allelic variants were detected for the Glu-A1 locus; one of them has not been previously described. For the Glu-B1 locus, three of the nine alleles detected have not been found before. A high degree of variation was evident for the LMW glutenin subunits, and up to 23 different patterns were detected for the B-LMW glutenin subunits. Considering both types of proteins (HMW and LMW), 30 combinations were found between all the evaluated lines. This wide polymorphism can be used to transfer new quality genes to wheat, and to widen its genetic basis. Received: 13 June 2000 / Accepted: 3 July 2000     

Characterization of two HMW glutenin subunit genes from Taenitherum Nevski

The compositions of high molecular weight (HMW) glutenin subunits from three species of Taenitherum Nevski (TaTa, 2n = 2x = 14), Ta. caput-medusae, Ta. crinitum and Ta. asperum, were investigated by SDS-PAGE analysis. The electrophoresis mobility of the x-type HMW glutenin subunits were slower or equal to that of wheat HMW glutenin subunit Dx2, and the electrophoresis mobility of the y-type subunits were faster than that of wheat HMW glutenin subunit Dy12. Two HMW glutenin genes, designated as Tax and Tay, were isolated from Ta. crinitum, and their complete nucleotide coding sequences were determined. Sequencing and multiple sequences alignment suggested that the HMW glutenin subunits derived from Ta. crinitum had the similar structures to the HMW glutenin subunits from wheat and related species with a signal peptide, and N- and C-conservative domains flanking by a repetitive domain consisted of the repeated short peptide motifs. However, the encoding sequences of Tax and Tay had some novel modification compared with the HMW glutenin genes reported so far: (1) A short peptide with the consensus sequences of KGGSFYP, which was observed in the N-terminal of all known HMW glutenin genes, was absent in Tax; (2) There is a specified short peptide tandem of tripeptide, hexapeptide and nonapeptide and three tandem of tripeptide in the repetitive domain of Tax; (3) The amino acid residues number is 105 (an extra Q presented) but not 104 in the N-terminal of Tay, which was similar to most of y-type HMW glutenin genes from Elytrigia elongata and Crithopsis delileana. Phylogenetic analysis indicated that Tax subunit was mostly related to Ax1, Cx, Ux and Dx5, and Tay was more related to Ay, Cy and Ry.     

Photosynthetic performance in wild emmer wheat,Triticum dicoccoides: ecological and genetic predictability

Summary In a twin study, we have shown that wild emmer wheat, Triticum dicoccoides, the progenitor of all cultivated wheats, harbours important genetic variation (Vg) in photosynthetic characteristics. This Vg resides within and between populations and ecogeographical regions in Israel, which is the center of origin and diversity of wild emmer wheat. Here we analyzed, by univariate and multivariate methods, the significant differentiation of variation in photosynthetic characteristics of 107 genotypes from 27 populations of wild emmer in Israel, distributed in three ecogeographical regions including central, xeric (northern cold and eastern warm) marginal, and mesic (western) marginal populations. The highest photosynthetic efficiency was displayed by populations of the xeric marginal region, but most variation for photosynthetic capacity occurs between accessions within ecogeographical regions and populations. Genotypes and populations of T. dicoccoides having high photosynthetic capacity can be identified by climatic factors and isozyme markers. The identification by genetic markers, if substantiated by testcrosses, can facilitate the maximization of conservation, in situ or ex situ, and utilization of these photosynthetic genetic resources for improvement of hexaploid wheat (T. aestivum).     

Identification and molecular characterization of a large insertion within the repetitive domain of a high-molecular-weight glutenin subunit gene from hexaploid wheat

High-molecular-weight (HMW) glutenin subunits are a particular class of wheat endosperm proteins containing a large repetitive domain flanked by two short N- and C-terminal non-repetitive regions. Deletions and insertions within the central repetitive domain has been suggested to be mainly responsible for the length variations observed for this class of proteins. Nucleotide sequence comparison of a number of HMW glutenin genes allowed the identification of small insertions or deletions within the repetitive domain. However, only indirect evidence has been produced which suggests the occurrence of substantial insertions or deletions within this region when a large variation in molecular size is present between different HMW glutenin subunits. This paper represents the first report on the molecular characterization of an unusually large insertion within the repetitive domain of a functional HMW glutenin gene. This gene is located at the Glu-D1 locus of a hexaploid wheat genotype and contains an insertion of 561 base pairs that codes for 187 amino acids corresponding to the repetitive domain of a HMW glutenin subunit encoded at the same locus. The precise location of the insertion has been identified and the molecular processes underlying such mutational events are discussed.     

High molecular weight glutenin subunit variation in Triticum turgidum var. dicoccum

Summary Variation in high molecular weight (HMW) glutenin subunit composition among 167 accessions of dicoccum wheat (Triticum turgidum L. var. dicoccum Schrank) of diverse origins was investigated using one-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). A total of 20 alleles were identified, and 9 of them were found to be different from those previously detected by Payne and Lawrence (1983 b) in hexaploid wheat (Triticum aestivum L.). The newly discovered alleles enhance the genetic variability available to improve the industrial quality of wheats and some of them may facilitate basic research on the relationship of industrial quality with HMW glutenin subunit number. The novel variants include a GLU-A1 encoded subunit which has higher molecular mass than any other so far described in tetraploid and hexaploid wheats, and a null GLU-B1 allele. Dicoccums containing neither GLU-A1- nor GLU-B1-encoded subunits were also identified. A comparison of the mean number of HMW glutenin subunits contained in various primitive and modern domesticated wheats of different ploidy levels and the identification of wheats containing no HMW glutenin subunits suggest that the occurrence of null GLU-1 alleles in these species depends on chance rather on an inherent tendency on the part of modern polyploid wheats to suppress the activity of redundant GLU-1 genes.     

Ecogeographical distribution of HMW glutenin alleles in populations of the wild tetraploid wheat Triticum turgidum var. dicoccoides

Summary Polymorphism of high molecular weight (HMW) glutenin subunits in 466 accessions of the wild tetraploid wheat Triticum turgidum var. dicoccoides in Israel was characterized with regard to the ecogeographical distribution of the HMW glutenin alleles, both between and within 22 populations, and along transects in a single population. While some populations were monomorphic for all the HMW glutenin loci, namely, Glu-A1-1, Glu-A1-2, Glu-B1-1 and Glu-B1-2, others contained up to four alleles per locus. Intrapopulation variability could be predicted by the geographical distribution: marginal populations tended to be more uniform than those at the center of distribution. The various HMW glutenin alleles tended to be clustered, both at a regional level and within a single population along transects of collection. It is suggested that this clustering is due to selection pressures acting both at a regional and at a microenvironmental level. This was confirmed by the significant correlations found between the MW of subunits encoded by Glu-A1-1 and the populations' altitude, average temperature and rainfall. The possible selective values of seed storage proteins are discussed.     

Wheat storage proteins: glutenin DNA diversity in wild emmer wheat,Triticum dicoccoids,in Israel and Turkey. 3. Environmental correlates and allozymic associations

The diversity of high-molecular-weight (HMW) and low-molecular-weight (LMW) glutenin subunits in the tetraploid wild progenitor of wheat, Triticum dicoccoides, was studied at the DNA level by the polymerase chain reaction (PCR). The DNA diversity of HMW and LMW glutenins was shown to be correlated to environmental physical and biotic factors (climate, soil and pathogen resistance) and to allozyme variation. We conclude that glutenin DNA diversity is nonrandomly distributed and could be more optimally sampled in nature for future breeding programmes to improve bread quality.     

Allelic diversity of high-molecular-weight glutenin protein subunits in natural populations of Dasypyrum villosum (L.) Candargy

Dasypyrum villosum (L.) Candargy (2n=14, V genome) is a wild, allogamous, diploid grass species that is a potential genetic resource for wheat improvement. The diversity of high-molecular-weight (HMW) glutenin subunits of the seed storage proteins of this species was examined in populations sampled in their natural habitats in Italy and Yugoslavia where the species is widely distributed. The results of selfed progeny tests confirmed that the allelic variation of HMW-glutenin subunits in D. villosum is controlled by a single locus (Glu-V1). Fourteen alleles at Glu-V1 were found among 982 individuals representing 12 populations from Italy and two from Yugoslavia, with a mean of seven alleles per population. Among the 14 Glu-V1 alleles, one produced no HMW-glutenin subunits, ten coded for a single subunit, and three for two subunits. The mobilities of all the subunits in SDS-PAGE gels were greater than that of reference subunit 7 of Triticum aestivum cv Chinese Spring. Eight of the alleles were relatively abundant (mean frequency over all populations ranged from 0.08 to 0.17) and distributed widely among the 14 populations (8 to 14); five of the alleles were rare (0.003 to 0.021) and found in only 1 to 5 populations. The frequencies of two alleles could not be individually estimated because of the similar electrophoretic mobility of their subunits. The multiple-allelic diversity at Glu-V1 was high (H_e ranged from 0.700 to 0.857) but similar from population to population. Overall, about 7% of the total allelic variation was distributed among populations (G_st=0.072), and more than 90% within populations. Whether the allelic variation at Glu-V1 is subject to natural selection is unknown, but the discovery of the homozygous null Glu-V1 alleles in the present study may be useful in pursuing this question. The multiple-allelic diversity in Glu-V1 presents the plant breeder with an opportunity to evaluate and select the most useful alleles for transfer to wheat. The importance of an evaluation genetic diversity in a wild species before interspecific gene transfers are attempted is well illustrated in this study.     

High-molecular-weight glutenin subunit variation in Turkish emmer wheat [Triticum turgidum L. ssp. dicoccon (Schrank) Thell.] landraces

The genetic diversity of high-molecular-weight (HMW) glutenin subunits in 18 cultivated emmer wheat landrace populations, originating from Turkey, was investigated using sodium dodecyl sulphate polyacrylamide gel electrophoresis. The mean number of alleles (n _a) and effective alleles (n _ea) were observed as 3.67 and 1.53, respectively. The mean values of expected heterozygosity (gene diversity) (H _e) and average heterozygosity (H _e,av) were calculated as 0.31 and 0.12, respectively. Actual genetic differentiation (D) and gene flow (N _m) between the different populations were observed as 0.24 and 0.16, respectively. Statistical analysis of Pearson’s correlation, multiple regressions and principal component analysis indicated that eco-geographical variables have a significant effect on HMW-glutenin diversity. Considering the dramatic decrease in genetic diversity of modern high-yielding cultivars, the conservation of genetic diversity in these wheat landraces, and in other old cultivars, is important for improving modern monocultures and their ability to resist biotic and abiotic conditions caused by climate changes, thus generating a wide adaption to a variety of environmental conditions. Adoptation measures for germplasm conservation of Turkish emmer wheat landraces and utilisation of their germplasm for improvement of modern wheat varieties were discussed in this study.     

Use of recombinant inbred lines of wheat for study of associations of high-molecular-weight glutenin subunit alleles to quantitative traits

Summary The high-molecular-weight glutenin subunits (HMW glutenin), encoded by alleles at homoeologous lociGlu-A1,Glu-B1, andGlu-D1 on the long arms of chromosomes1A,1B, and1D of a set of F₈ random recombinant inbred lines (RIL) derived from the bread wheat cross Anza × Cajeme 71, were classified by SDS-PAGE. Anza has poor breadmaking quality and HMW-glutenin subunits (Payne numbers) null (Glu-A1c), 7+8 (Glu-B1b), and 2+12 (Glu-D1a); Cajeme 71 has good quality and 1 (Glu-A1a), 17+18 (Glu-B1i), and 5+10 (Glu-D1d). The combinations of these alleles in the RIL were examined for associations with grain yield and four indicators of grain quality — protein content, yellowberry, pearling index, and SDS sedimentation volume. Data were obtained from a field experiment with three nitrogen fertilization treatments on 48 RIL and the parents. Orthogonal partitioning of the genetic variance associated with the three HMW glutenin subunit loci into additive and epistatic (digenic and trigenic) effects showed strong associations of these loci with grain yield and the indicators of quality; however, the associations accounted for no more than 25% of the differences between the parents. Genetic variance was detected among the RIL, which had the same HMW glutenin genotype for all traits. Epistatic effects were absent for grain yield and yellowberry, but were substantial for grain protein content, pearling index, and SDS sedimentation volume. All three loci had large single-locus additive effects for grain yield, protein, and SDS sedimentation volume. Yellowberry was largely influenced byGlu-B1 andGlu-D1, whereas pearling index was associated withGlu-A1 andGlu-B1. Even though the observed associations-of effects of HMW glutenin loci with the quantitative characters were small relative to the total genetic variability, they are of considerable importance in understanding the genetics of wheat quality, and are useful in the development of new wheat varieties with specific desired characteristics.     

High molecular weight glutenin subunit in durum wheat (T. durum)

Summary The diversity of high molecular weight (HMW) glutenin subunits of 502 varieties of durum wheat (Triticum durum) from 23 countries was studied using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Twenty-nine types of patterns were observed with 18 mobility bands. A total of 18 alleles were identified by comparing the mobilities of their subunits to those previously found in hexaploid wheat (T. aestivum) and in Triticum turgidum var. dicoccum. Five new alleles were detected: two on the Glu A1 and three on the Glu B1 locus. Comparison of the frequency of alleles in the three species T. aestivum, T. dicoccum and T. durum was investigated. Significant differences exist between each of these species on the basis of the frequency distributions of their three and four common alleles at the Glu A1 and Glu B1 locus, respectively. The Glu B1c allele occuring very frequently in hexaploid wheats was not found in the two tetraploid species. More than 83% of the T. durum analysed were found to have the Glu A1c (null) allele.     

High molecular weight glutenin subunit variation in wild and cultivated einkorn wheats (Triticum spp.,Poaceae)

Variation in high molecular weight (HMW) glutenin subunit composition among wild and cultivated einkorn wheats (2n = 2x = 14, AA) was investigated using one- (SDS-PAGE and urea/SDS-PAGE) and two-dimensional (IEF × SDS-PAGE) electrophoretic analyses. The material comprised 150 accessions ofTriticum urartu, 160 accessions ofT. boeoticum, 24 accessions ofT. boeoticum subsp.thaoudar and 74 accessions of primitive domesticatedT. monococcum from many different germplasm collections. The biochemical characteristics of HMW-glutenin subunits ofT. boeoticum andT. monococcum were highly similar to one another but distinctly different from those ofT. urartu. All the species analysed were characterised by large intraspecific variation and only three HMW-glutenin subunit patterns were identical betweenT. boeoticum andT. monococcum. Consistent with the distinct nature ofT. urartu, all its HMW-glutenin patterns were different from those found inT. boeoticum andT. monococcum. The differences detected between these species might reflect their reproductive isolation and are consistent with recent nomenclatural and biosystematic treatments that recogniseT. urartu as separate species fromT. boeoticum andT. monococcum. The presence of three distinct glutenin components in some accessions of the species studied seems to be evidence for the existence of at least three active genes controlling the synthesis of the HMW-glutenin subunits in the A genome of wild and primitive domesticated diploid wheats. Results indicate also that HMW-glutenin subunits could represent useful markers for the evaluation of genetic variability present in different wild diploid wheat collections and subsequently for their conservation and future utilisation.     

Molecular characterization of the HMW glutenin genes Dt x1.5?+?Dt y10 from Aegilops tauschii and their PCR-mediated recombinants

The high molecular weight (HMW) glutenin subunits, D^tx1.5 + D^ty10, are special types of storage proteins found in Aegilops tauschii that are never found in common wheat (Triticum aestivum). This study reports the characterization of the complete open reading frames (ORFs) of the HMW glutenin genes, D^tx1.5 and D^ty10, using a restrict-enzyme based method named the restricted deletion method (RDM). The D^tx1.5 and D^ty10 were found to have an identical structure compared with the other published HMW glutenin genes. Comparison of the deduced protein sequences also indicated that the D^ty10 in Ae. tauschii differed from its counterpart Dy10 in common wheat, by having insertions and deletions in the central repetitive domain. This result confirms the two subunits with same mobility in SDS-PAGE are different types of HMW glutenin subunits. In addition, four PCR-mediated recombinants of the D^tx1.5 and D^ty10 genes were amplified using a PCR program with shorter extension time. The recombinants had a similar structure to their corresponding natural genes, but a significantly different central repetitive domain. Western blot analysis exhibited a normal expression of the recombinants in E. coli. In addition to its usefulness for studying structure and function of the HMW glutenin subunits, the PCR-mediated recombination may provide an efficient method to generate novel HMW glutenin genes for wheat breeding.     

Genetic diversity for grain nutrients in wild emmer wheat: potential for wheat improvement

Background and Aims

Micronutrient malnutrition, particularly zinc and iron deficiency, afflicts over three billion people worldwide due to low dietary intake. In the current study, wild emmer wheat (Triticum turgidum ssp. dicoccoides), the progenitor of domesticated wheat, was tested for (1) genetic diversity in grain nutrient concentrations, (2) associations among grain nutrients and their relationships with plant productivity, and (3) the association of grain nutrients with the eco-geographical origin of wild emmer accessions.

Methods

A total of 154 genotypes, including wild emmer accessions from across the Near Eastern Fertile Crescent and diverse wheat cultivars, were characterized in this 2-year field study for grain protein, micronutrient (zinc, iron, copper and manganese) and macronutrient (calcium, magnesium, potassium, phosphorus and sulphur) concentrations.

Key Results

Wide genetic diversity was found among the wild emmer accessions for all grain nutrients. The concentrations of grain zinc, iron and protein in wild accessions were about two-fold greater than in the domesticated genotypes. Concentrations of these compounds were positively correlated with one another, with no clear association with plant productivity, suggesting that all three nutrients can be improved concurrently with no yield penalty. A subset of 12 populations revealed significant genetic variation between and within populations for all minerals. Association between soil characteristics at the site of collection and grain nutrient concentrations showed negative associations between soil clay content and grain protein and between soil-extractable zinc and grain zinc, the latter suggesting that the greatest potential for grain nutrient minerals lies in populations from micronutrient-deficient soils.

Conclusions

Wild emmer wheat germplasm offers unique opportunities to exploit favourable alleles for grain nutrient properties that were excluded from the domesticated wheat gene pool.     

Chromosomal location of genes for novel glutenin subunits and gliadins in wild emmer wheat (<Emphasis Type="Italic">Triticum turgidum</Emphasis> L. var.<Emphasis Type="Italic"> dicoccoides</Emphasis>)

The glutenin and gliadin proteins of wild emmer wheat, Triticum turgidum L. var. dicoccoides, have potential for improvement of durum wheat (T. turgidum L. var. durum) quality. The objective of this study was to determine the chromosomes controlling the high molecular weight (HMW) glutenin subunits and gliadin proteins present in three T. turgidum var. dicoccoides accessions (Israel-A, PI-481521, and PI-478742), which were used as chromosome donors in Langdon durum- T. turgidum var. dicoccoides (LDN-DIC) chromosome substitution lines. The three T. turgidum var. dicoccoides accessions, their respective LDN-DIC substitution lines, and a number of controls with known HMW glutenin subunits were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), urea/SDS-PAGE, and acid polyacrylamide gel electrophoresis (A-PAGE). The results revealed that all three T. turgidum var. dicoccoides accessions possess Glu-A1 alleles that are the same as or similar to those reported previously. However, each T. turgidum var. dicoccoides accession had a unique Glu-B1 allele. PI-478742 had an unusual 1Bx subunit, which had mobility slightly slower than the 1Ax subunit in 12% SDS-PAGE gels. The subunits controlled by chromosome 1B of PI-481521 were slightly faster in mobility than the subunits of the Glu-B1n allele, and the 1By subunit was identified as band 8. The 1B subunits of Israel-A had similar mobility to subunits 14 and 16. The new Glu-B1 alleles were designated as Glu-B1be in Israel-A, Glu-B1bf in PI-481521, and Glu-B1bg in PI-478742. Results from A-PAGE revealed that PI-481521, PI-478742, and Israel-A had eight, 12, and nine unique gliadin bands, respectively, that were assigned to specific chromosomes. The identified glutenin subunits and gliadin proteins in the LDN-DIC substitution lines provide the basis for evaluating their effects on end-use quality, and they are also useful biochemical markers for identifying specific chromosomes or chromosome segments of T. turgidum var. dicoccoides.Communicated by B. Friebe     

Genetic diversity for drought resistance in wild emmer wheat and its ecogeographical associations

Wild emmer wheat (Triticum turgidum spp. dicoccoides (Körn.) Thell.), the tetraploid progenitor of cultivated wheat, is a potential source for various agronomical traits, including drought resistance. The objectives of this study were to characterize (1) the genetic diversity for drought resistance in wild emmer wheat, and (2) the relationship between drought responses of the wild emmer germplasm and the ecogeographical parameters of its collection sites. A total of 110 wild emmer accessions consisting of 25 populations and three control durum wheat cultivars were examined under two irrigation regimes, well-watered (’wet’) and water-limited (’dry’). Wide genetic diversity was found both between and within the wild emmer populations in most variables under each treatment. A considerable number of the wild emmer accessions exhibited an advantage in productivity (spike and total dry matter) over their cultivated counterparts. Most wild emmer wheat accessions exhibited a greater carbon isotope ratio (δ¹³C, indicating higher water-use efficiency) under the dry treatment and higher plasticity of δ¹³C relative to the cultivated controls, which may have contributed to the drought adaptations in the former. The most outstanding drought-tolerance capacity (in term of productivity under the dry treatment and susceptibility indices) was detected in wild emmer populations originated from hot dry locations. The results suggest that wild emmer has the potential to improve drought resistance in cultivated wheat.     

Grain zinc, iron and protein concentrations and zinc-efficiency in wild emmer wheat under contrasting irrigation regimes

Micronutrient malnutrition, and particularly deficiency in zinc (Zn) and iron (Fe), afflicts over three billion people worldwide, and nearly half of the world’s cereal-growing area is affected by soil Zn deficiency. Wild emmer wheat [Triticum turgidum ssp. dicoccoides (Körn.) Thell.], the progenitor of domesticated durum wheat and bread wheat, offers a valuable source of economically important genetic diversity including grain mineral concentrations. Twenty two wild emmer wheat accessions, representing a wide range of drought resistance capacity, as well as two durum wheat cultivars were examined under two contrasting irrigation regimes (well-watered control and water-limited), for grain yield, total biomass production and grain Zn, Fe and protein concentrations. The wild emmer accessions exhibited high genetic diversity for yield and grain Zn, Fe and protein concentrations under both irrigation regimes, with a considerable potential for improvement of the cultivated wheat. Grain Zn, Fe and protein concentrations were positively correlated with one another. Although irrigation regime significantly affected ranking of genotypes, a few wild emmer accessions were identified for their advantage over durum wheat, having consistently higher grain Zn (e.g., 125 mg kg^?1), Fe (85 mg kg^?1) and protein (250 g kg^?1) concentrations and high yield capacity. Plants grown from seeds originated from both irrigation regimes were also examined for Zn efficiency (Zn deficiency tolerance) on a Zn-deficient calcareous soil. Zinc efficiency, expressed as the ratio of shoot dry matter production under Zn deficiency to Zn fertilization, showed large genetic variation among the genotypes tested. The source of seeds from maternal plants grown under both irrigation regimes had very little effect on Zn efficiency. Several wild emmer accessions revealed combination of high Zn efficiency and drought stress resistance. The results indicate high genetic potential of wild emmer wheat to improve grain Zn, Fe and protein concentrations, Zn deficiency tolerance and drought resistance in cultivated wheat.     

小麦新品种(系)Glu-1位点等位基因变异研究

应用SDS-PAGE技术分析了40份小麦新品种(系)的高分子量麦谷蛋白亚基等位基因变异。在Glu-1位点共检测到10种变异类型,其中Glu-Al位点有3种类型：Null、1、26 ,Glu-B1位点有5种类型：7 8、7 9、14 15、7、17 18,Glu-D1位点有2种类型：2 12、5 10;Null(54．3％)、7 8(51．4％)和2 12(62．9％)分别是Glu-Al、Glu-B1和Glu-D1位点上的主要亚基变异类型。另外,在2份材料的Glu-B1和Glu-D1位点各检测到1个新的亚基,分别命名为1By8．1和1Dx5^ 。Glu-1位点的Nei‘s遗传变异指数平均为0,5648,Glu-B1的遗传多样性最高,Glu-D1最低。供试小麦材料Glu-1位点的HMW-GS组合共有17种类型,以(Null,7 8,2 12)组合为主要类型,占31．4％;有9种亚基组合类型分别只在1份材料中出现,占26.1％。结果表明,这些小麦新品种(系)存在着丰富的亚基组合类型。     

HMW and LMW glutenin alleles among putative tetraploid and hexaploid European spelt wheat (<Emphasis Type="Italic">Triticum spelta</Emphasis> L.) progenitors

The allelic compositions of high- and low-molecular-weight subunits of glutenins (HMW-GS and LMW-GS) among European spelt (Triticum spelta L.) and related hexaploid and tetraploid Triticum species were investigated by one- and two-dimensional polyacrylamide-gel electrophoresis (PAGE) and capillary electrophoresis (CE). A total of seven novel glutenin alleles (designated A1a*, B1d*, B1g*, B1f*, B1j*, D1a* at Glu-1 and A3h at the Glu-3 loci, respectively) in European spelt wheat were detected by SDS-PAGE, which were confirmed further by employing A-PAGE and CE methods. Particularly, two HMW-GS alleles, Glu-B1d* coding the subunits 6.1 and 22.1, and Glu-B1f* coding the subunits 13 and 22*, were found to occur in European spelt with frequencies of 32.34% and 5.11%, respectively. These two alleles were present in cultivated emmer (Triticum dicoccum), but they were not observed in bread wheat (Triticum aestivum L.). The allele Glu-B1g* coding for 13* and 19* subunits found in spelt wheat was also detected in club wheat (Triticum compactum L.). Additionally, two alleles coding for LMW-GS, Glu-A3h and Glu-B3d, occurred with high frequencies in spelt, club and cultivated emmer wheat, whereas these were not found or present with very low frequencies in bread wheat. Our results strongly support the secondary origin hypothesis, namely European spelt wheat originated from hybridization between cultivated emmer and club wheat. This is also confirmed experimentally by the artificial synthesis of spelt through crossing between old European emmer wheat, T. dicoccum and club wheat, T. compactum.Communicated by H.F. Linskens     

Resistance of wild wheat to stripe rust: Predictive method by ecology and allozyme genotypes

From 114 accessions of wild emmer wheat from 11 sites in Israel, known for their allozymic variation (Nevo & al. 1982), individual genotypes were tested for resistance to one isolate of stripe rust both in the seedling stage in a growth chamber and in the adult plant stage in the field. The results indicate that resistance to stripe rust in seedlings and adults are significantly correlated (r_s = 0.40, p < 0.001). Genetic polymorphisms of resistance to stripe rust vary geographically and are predictable by climatic, as well as allozymic markers. Three variable combinations of rainfall, evaporation, and temperature explain significantly 0.40–0.53 of the spatial variance in disease resistance to stripe rust, suggesting the operation of natural selection. Several allozyme genotypes are significantly associated with disease resistance. We conclude that natural populations of wild emmer wheat in Israel contain large amounts of disease resistance genes. These populations could be effectively screened and then utilized by the phytopathologist for identifying resistant genotypes and producing new resistant cultivars.Patterns of Resistance of Wild Wheat to Pathogens in Israel II.