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1.
Summary Aegilops tauschii (Coss.) Schmal. (2n = 2x = 14, DD), a wild relative of wheat has been considered to be a valuable source of variation for improvement of cultivated wheats. However, undesirable genes can be incorporated into the cultivated varieties from wild relatives. The spontaneous spike shattering caused by the brittle rachis character is of adaptive value in wild grass species, but not in cultivated varieties. The rachis of R-61, which was derived from the cross of T. aestivum cv. Bet Hashita with an accession of Ae. tauschii, was brittle. Using telosomic stocks, the brittle rachis gene Br 61 (tentatively designated) of B-61 was located on the short arm of chromosome 3D and the distance of Br 61 to the centromere was 31.9 cM. The distance of Br 61 from the centromeric marker Xgdm72 was 25.3 cM on the short arm of chromosome 3D. The location of Br 61 was similar to Br 1 whose location was determined by telosomic mapping and microsatellite mapping. Discrepancy of disarticulation type was found between R-61 and Aegilops tauschii suggesting that the recombination around the regions of Br 1 locus and Br t locus created the wedge type disarticulation of R-61.  相似文献   

2.
Two major genes controlling leaf pubescence were mapped on chromosomes 4BL (Hl1) and 7BS (Hl2 Aesp ) in wheat (Saratovskaya 29) and a wheat/Aegilops introgression line (102/00I), respectively, together with quantitative trait loci (QTLs) determining hairiness of the leaf margin (QHl.ipk-4B, QHl.ipk-4D) and auricle (QPa.ipk-4B, QPa.ipk-4D) on the long arms of chromosomes 4B and 4D, respectively. The QTLs on chromosome 4D were contributed by a synthetic wheat and, therefore, originated from Aegilops tauschii. The homoeologous group 4 wheat/A. tauschii genes/QTLs detected in the present study were aligned with the barley pubescence genes Hln/Hsh and Hs b and the hairy peduncle rye gene Hp1. The locus seems to be pleiotropically responsible for the pubescence of different plant organs in different species of the Triticeae. Another homoeologous series may be present on the short arms of the homoeologous group 7 chromosomes, based on the results of an allelic test cross between the Chinese local cultivar Hong-mang-mai carrying Hl2 and the wheat/Aegilops speltoides introgression line 102/00I.  相似文献   

3.
Variability of high molecular weight glutenin subunits (HMW-GS) was studied in198 accessions of Ae. Tauschii (2n=2x=14, DD) by sodium dodecyl sulphate(SDS-PAGE) and acid polyacrylamide gel electrophoresis (A-PAGE) and capillary electrophoresis (CE). A high allelic variation of HMW-GS, including some novel x- and y-type subunits and variable subunit combinations were observed. One accession(TD159) showed a x-type null form. The results by A-PAGE analysis revealed that the subunits Dx5 t and Dy10 t encoded by Glu-D t 1 locus in Ae. tauschii were different in relative mobilities in comparison with the subunits Dx5 and Dy10 found in bread wheats, whereas they had the same mobilities, respectively, when separated by SDS-PAGE. The higher resolution of Ae. tauschii HMW-GS separated by CE method showed two clear peaks in accordance with x- and y-type subunits, respectively,except the accession TD151 which possessed only subunit Dy12.1*t. The electro elution time of the x-type and y-type subunits were about 13–14 and 7–8minutes, respectively. Characterization of wheat HMW-GS was facilitated by using CE which provides high resolution and increases the speed of analysis in conjunction with the traditional gel electrophoretic methods. A total of 42HMW-GS alleles were identified, among which were several alleles not presently detected in bread wheats. Hence Ae. tauschii is potentially a valuable genetic resource for quality improvement of bread wheat. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

4.
The leaf and stem surfaces of many land plants are covered with a cuticular wax layer that confers a glaucous appearance or white bloom. Synthetic hexaploid wheat Line 3672 was non-glaucous, and common wheat Line 9753 was glaucous. The cuticular wax was characterized using Scanning Electron Microscopy (SEM). A hybrid using 9753 as female parent and 3672 as male parent was made and 108 F2 plants and their F3 progenies were used to map the non-glaucouness gene. Non-glaucousness in Line 3672 was controlled by a single dominant gene, temporarily designated Iw3672. Five SSR markers mapped on chromosome 2DS were linked to Iw3672. Additionally, two EST-derived markers and a SNP marker were developed and were also linked to Iw3672. The order of the eight markers and Iw3672 was Xte6 730 /Xbarc124 520 —Iw3672 —Xwe6 2100/2150 —Xcau96 287 —Xcfd51 180/200/230 —Xwe7—Xgdm5 190 —Xgdm35 246/250 , with the genetic distance for each interval being 0.9 cM, 1.4 cM, 0.9 cM, 0.9 cM, 1.9 cM, 7.2 cM and 2.5 cM, respectively. We concluded that Iw3672 is physically mapped on the distal region of wheat chromosome 2DS.  相似文献   

5.
Leaf and stripe rusts are severe foliar diseases of bread wheat. Recently, chromosomes 5Mg from the related species Aegilops geniculata that confers resistance to both leaf and stripe rust and 5Ut from Ae. triuncialis conferring resistance to leaf rust have been transferred to bread wheat in the form of disomic DS5Mg(5D) and DS5Ut(5A) chromosome substitution lines. The objective of this study was to shorten the alien segments in these lines using Ph I-mediated, induced homoeologous recombination. Putativerecombinants were evaluated for their rust resistance, and by genomic in situ hybridization and microsatellite analyses. One agronomically useful wheat-Ae. geniculata recombinant resistant to leaf and stripe rust was identified that had only a small terminal segment of the 5MgL arm transferred to the long arm of an unidentified wheat chromosome. This germplasm can be used directly in breeding programs. Only one leaf rust-resistant wheat-Ae. triuncialis recombinant, which consists of most of the complete 5Ut chromosome with a small terminal segment derived from 5AS, was identified. This germplasm will need further chromosome engineering before it can be used in wheat improvement. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

6.
The spikes of club wheat are significantly more compact than spikes of common wheat due to the action of the dominant allele of the compactum (C) locus. Little is known about the location of C on chromosome 2D and the relationship between C and to other spike-compacting genes. Thus, a study was undertaken to place C on linkage maps and a chromosome deletion bin, and to assess its relatedness to the spike compacting genes zeocriton (Zeo) from barley and soft glume (Sog) from T. monococcum. Genetic mapping was based on recombinant inbred lines (RILs) from a cross between the cultivars Coda (club) and Brundage (common) and F2 progeny from a cross between the club wheat Corrigin and a chromosome 2D substitution line [Chinese Spring (Ae. tauschii 2D)]. The C locus was flanked by Xwmc144 and Xwmc18 in the RIL population and it was completely linked to Xcfd116, Xgwm358 and Xcfd17 in the F2 population. C could not be unambiguously placed to a chromosome bin because markers that were completely linked to C or flanked this locus were localized to chromosome bins on either side of the centromere (C-2DS1 and C-2DL3). Since C has been cytogenetically mapped to the long arm of chromosome 2D, we suspect C is located in bin C-2DL3. Comparative mapping suggested that C and Sog were present in homoeologous regions on chromosomes 2D and 2Am, respectively. On the other hand, C and Zeo, on chromosome 2H, did not appear to be orthologous.  相似文献   

7.
Synthetic hexaploid wheats are of interest to wheat breeding programs, especially for introducing new genes that confer resistance to biotic and abiotic stresses. A group of 54 synthetic hexaploid wheats derived from crosses between emmer wheat(Triticum dicoccum, source of the A and B genomes) and goat grass (Aegilops tauschii, D genome donor) were investigated for genetic diversity. Using the AFLP technique, dendrograms revealed clear grouping according to geographical origin for the T. dicoccum parents but no clear groups for the Ae. tauschii parents. The geographical clustering of the T. dicoccum parents was also reflected in the dendrogram of their derived synthetic hexaploids. Diversity of the T. dicoccum parents and their derived synthetic hexaploids was further evaluated by measuring 18morphological and agronomic traits on the plants. Clustering based on morphological and agronomic data also reflected geographical origin. However, comparison of genetic distances obtained from AFLP and agronomic data showed no correlation between the two diversity measurements. Nevertheless, similarities among major clusters with the two systems could be identified. Based on percentage of polymorphic markers, the synthetic hexaploids had a considerably higher level of AFLP diversity (39%) than normally observed in cultivated hexaploid wheat (12–21%). This suggests that synthetic hexaploid wheats can be used to introduce new genetic diversity into the bread wheat gene pool. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

8.
The gene pool of Aegilops tauschii, the D-genome donor of common wheat (Triticum aestivum L.), can be easily accessed in wheat breeding, but remains largely unexplored. In our previous studies, many synthetic hexaploid wheat lines were produced through interspecific crosses between the tetraploid wheat cultivar Langdon and various A. tauschii accessions. The synthetic hexaploid wheat lines showed wide variation in many characteristics. To elucidate the genetic basis of variation in flowering-related traits, we analyzed quantitative trait loci (QTL) affecting time to heading, flowering and maturity, and the grain-filling period using four different F2 populations of synthetic hexaploid wheat lines. In total, 10 QTLs located on six D-genome chromosomes (all except 4D) were detected for the analyzed traits. The QTL on 1DL controlling heading time appeared to correspond to a flowering time QTL, previously considered to be an ortholog of Eps-A m 1 which is related to the narrow-sense earliness in einkorn wheat. The 5D QTL for heading time might be a novel locus associated with wheat flowering, while the 2DS QTL appears to be an allelic variant of the photoperiod response locus Ppd-D1. Some of the identified QTLs seemed to be novel loci regulating wheat flowering and maturation, including a QTL controlling the grain filling period on chromosome 3D. The exercise demonstrates that synthetic wheat lines can be useful for the identification of new, agriculturally important loci that can be transferred to, and used for the modification of flowering and grain maturation in hexaploid wheat.  相似文献   

9.
N. Watanabe  N. Ikebata 《Euphytica》2000,115(3):215-220
`Langdon' (LDN), a durum wheat (Triticum turgidum L. var. durum) cultivar, and a set of chromosome substitution lines of Langdon, where A or B genome chromosome were replaced with a homologous chromosome of wild emmer wheat, T. turgidum ssp. dicoccoides (DIC), were used to assess the effect of the specific chromosome on seed dormancy in tetraploid wheat. The LDN(DIC 3A) and LDN (DIC 313) lines showed significantly lower seed germination than Langdon. It appears that LDN(DIC 3A) and LDN(DIC 3B) have red grain whose allele were designated as R-A1b and R-B1b, respectively and the rachises of LDN(DIC 3A) and LDN(DIC 3B) were fragile. The alleles for brittle rachis were designated as Br 2 for LDN(DIC 3A) and Br 3 for LDN(DIC 3B). From the F2 of the crosses, Langdon/LDN(DIC 3A) and Langdon/LDN(DIC 3B), Br 2 was located approximately 44.2 cM from the R-A1b locus and Br 3 approximately 47.0 cM from the R-B1b locus, respectively. Recombinant inbred chromosomal lines for 3A and 3B were used to assess (1) the linkage relationship between grain colour and fragile rachis, and (2) the effect of grain colour on germination. Estimated distance between R-B1b – Br 2 was 39.6 cM. For the 3A population, germination percentage of both colour groups was 12.4% for the red grain group and 68.6% for the amber group, respectively. For the 3B population, germination percentage of the red group was 7.3% and that of the amber group was 82.1%. For both populations, differences were statistical significant by t-tests. We considered that seed dormancy of T. turgidum ssp. dicoccoides was dependent on grain colour. It raised the possibility that brittle rachis is due to a paralogous gene set on homoeologous group 3 chromosomes. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

10.
It was recently shown that allopolyploidy brings novel epistatic interactions to genes belonging to different genomes. However, systematic studies of the phenotypic relationships between synthetic hexaploid wheats and their parental lines have not been conducted. In this study, 27 synthetic hexaploid wheats were produced by crossing the tetraploid wheat cultivar ‘Langdon’ with 27 accessions of Aegilops tauschii. Variations in 20 morphological and flowering traits were analysed in both the synthetic wheat lines and the parental Ae. tauschii accessions. The 20 traits exhibited large variations in the wheat lines. For many of the traits, the degree of variation in the parental accessions was reduced in the hexaploid derivatives. Principal component analysis of floret‐related traits divided the Ae. tauschii accessions into two subspecies, ssp. tauschii and ssp. strangulata, but this parental pattern of subspecific division was not detectable in the hexaploids. Our results suggest that the ‘Langdon’ genome may have an alleviating effect on the expression of D‐genome‐derived variations in derived synthetics.  相似文献   

11.
Wheat pre-breeding using wild progenitors   总被引：6，自引：1，他引：6  
J. J. Valkoun 《Euphytica》2001,119(1-2):17-23
To facilitate the use of wheat wild relatives in conventional breedingprograms, a wheat pre-breeding activity started at ICARDA in 1994/1995season. Preliminary results of gene introgression from wild diploidprogenitors, Triticum urartu, T. baeoticum, Aegilops speltoides andAe. tauschii and tetraploid T. dicoccoides are described. Crosseswith wild diploid Triticum spp. yielded high variation in plant andspike morphology. Synthetic hexaploids were produced from crosses of alocal durum wheat landrace `Haurani' with two Ae. tauschiiaccessions. Both Ae. tauschii accessions carry hybrid necrosis allelesthat gave necrotic plant phenotypes in crosses with some bread wheats.Backcross progenies with agronomical desirable traits, i.e. high spikeproductivity, short plant stature, earliness, drought tolerance and highproductive tillering, were identified in crosses of durum wheat with wild Triticum spp. and in a cross of one of the hexaploid synthetics with alocally adapted bread wheat cv. `Cham 6'. Resistance to yellow rust wasfound in durum wheat crosses with the three wild Triticum spp. andAe. speltoides and leaf rust resistance was identified in crosses withT. baeoticum and Ae. speltoides. The results show that wheatimmediate progenitors may be a valuable and readily accessible source ofnew genetic diversity for wheat improvement.  相似文献   

12.
Synthetic hexaploid wheat, produced by combining tetraploid wheat (AB genome) with Triticum tauschii (D genome), was crossed to modern hexaploid wheat (Triticum aestivum ABD genome) in an attempt to introduce new cold hardiness genes into the common hexaploid wheat gene pool. The cold hardiness levels of F) hybrids ranged from similar to parental means to equal to the hardy parent, indicating that cold hardiness was controlled by both additive and dominant genes. As expected when dominant gene action is involved, differences between F2 and parental means were smaller than comparable differences in the F., Frequency distributions of F2—derived F3 lines also suggested that dominant genes were involved in the control of cold hardiness in some crosses. Heritability estimates for cold hardiness ranged from 63 to 70 % indicating that selection for cold hardiness should be effective in populations arising from crosses between common and synthetic hexaploid wheat. However, high selection pressure on the progeny of crosses that included the most hardy T. aestivum, T. durum, and T. tauschii accessions as parents did not identify transgressive segregates for improved cold hardiness. These observations indicate that the close wheat relatives, sharing common genomes with T. aestivum, are not promising sources of new genes to increase the maximum cold hardiness potential of common hexaploid wheat.  相似文献   

13.
Triticum tauschii (Coss.) Schmal. is an ancestor of bread wheat (T. aestivum). This species has been widely used as a source ofsimply-inherited traits, but there are few reports of yield increases due tointrogression of genes from this species. Selections from F2-derivedlines of backcross derivatives of synthetic hexaploid wheats (T.turgidum / T. tauschii) were evaluated for grain yield in diverseenvironments in southern Australia. Re-selections were made in theF6 generation and evaluated for grain yield, yield componentsincluding grain weight, and grain growth characters in diverse environmentsin southern Australia and north-western Mexico. Re-selection was effectivein identifying lines which were higher yielding than the recurrent parent,except in full-irrigation environments. Grain yields of the selectedderivatives were highest relative to the recurrent parent in thelowest-yielding environments, which experienced terminal moisture deficitand heat stress during grain filling. The yield advantage of the derivativesin these environments was not due to a change in anthesis date orgrain-filling duration, but was manifest as increased rates of grain-filling andlarger grains, indicating that T. tauschii has outstanding potential forimproving wheat for low-yielding, drought-stressed environments.  相似文献   

14.
An unusually small y-type high molecular weight (HMW) glutenin subunit gene from Triticum tauschii was sequenced. This gene, encoded at the Glu-Dt1 locus was designated 12.4t and is the smallest HMW glutenin subunit gene described so far in Triticum species. Oligonucleotide primers based on published sequences of HMW glutenin genes were designed to amplify the encoding region and the central repetitive domain of the gene, which produced fragments of 1.4 and 0.85 kb, respectively. PCR products were cloned and sequenced. The derived amino acid sequence was compared with the amino acid sequences of the HMW glutenin subunits Dy12t, from T. tauschii, and subunits Dy10 and Dy12 of T. aestivum. The amino acid sequence deduced from the nucleotide sequence demonstrated that deletions of hexapeptides and nonapeptides were responsible for the reduction in the size of this HMW glutenin subunit. The estimated molecular weight of the Dy12.4t subunit, calculated on the basis of the deduced amino acid sequence, was 45,228 Daltons. There were also single amino acid differences in the N-, C-terminal and central repetitive domains of this gene in comparison to the three other y-type subunits encoded at the Glu-D1 locus. The Dy12.4t subunit showed the highest similarity to the Dy12 subunit present in the hexaploid wheat Chinese Spring.  相似文献   

15.
Y. M. Yan    S. L. K. Hsam    J. Z. Yu    Y. Jiang  F. J. Zeller 《Plant Breeding》2003,122(2):120-124
Gliadin variation at Gli‐Dt1 and Gli‐Dt2 loci in 198 Aegilops tauschii accessions was studied by acid polyacrylamide gel electrophoresis (A‐PAGE) and capillary electrophoresis (CE). High genetic polymorphisms were found at both gliadin coding loci, revealing a total of 184 and 169 gliadin variants at the Gli‐Dt1 and Gli‐Dt2 loci, respectively. In particular, 12 gliadin blocks encoded by different alleles were apparently expressed and readily identified in six synthetic hexaploids produced by hybridization between Triticum durum and Ae. tauschii accessions. Compared with Ae. tauschii ssp. eusquarrosa, the gliadin profile of the D genome in Ae. tauschii ssp. strangulata more resembles that of T. aestivum, supporting the view that the subspecies strangulata is the most likely progenitor of bread wheat. Capillary electrophoresis analysis showed that the method is capable of separating and characterizing gliadins with speed, in high resolution using small sample amounts, and is well‐suited to detect protein alleles and to identify desirable genotypes in wheat quality improvement.  相似文献   

16.
Synthetic hexaploid wheat is an effective genetic resource for transferring agronomically important genes from Aegilops tauschii to common wheat. Wide variation in grain size and shape, one of the main targets for wheat breeding, has been observed among Ae. tauschii accessions. To identify the quantitative trait loci (QTLs) responsible for grain size and shape variation in the wheat D genome under a hexaploid genetic background, six parameters related to grain size and shape were measured using SmartGrain digital image software and QTL analysis was conducted using four F2 mapping populations of wheat synthetic hexaploids. In total, 18 QTLs for the six parameters were found on five of the seven D-genome chromosomes. The identified QTLs significantly contributed to the variation in grain size and shape among the synthetic wheat lines, implying that the D-genome QTLs might be at least partly functional in hexaploid wheat. Thus, synthetic wheat lines with diverse D genomes from Ae. tauschii are useful resources for the identification of agronomically important loci that function in hexaploid wheat.  相似文献   

17.
Greater variability in starch properties is found in lower ploidy wheats than in commercial hexaploid wheats. This paper reports on the starch properties and variability in granule bound starch synthase (GBSS) loci of 17 diploid (Aegilops tauschii) and 12 tetraploid (durums) potential progenitors of wheat, compared with 29 synthetic hexaploid wheats produced from such progenitors. Starch properties examined were granule size distribution, swelling power, amylose content, gelatinisation and amylose-lipid dissociation properties. A PCR screening method was able to detect the presence or absence of each of the three GBSS genes. It also detected polymorphisms in eight diploids and nine hexaploids, all displaying the same 25 bases deletion in the D genome allele of GBSS. Two tetraploids and five hexaploids were null 4A for GBSS. There was little difference in the amylose contents and amylose-lipid dissociation peak temperatures of the synthetic hexaploids and the lower ploidy wheats. The synthetic hexaploids showed intermediate swelling power values with the durums giving the highest swelling powers. The durums also had higher B granule contents than the A. tauschii accessions, but not as high as the synthetics. However, the A. tauschii samples gave the highest gelatinisation peak temperatures. The presence of the null 4A mutation was positively correlated with swelling power, amylose content and DSC measurements. The new smaller D genome allele of GBSS was associated with slightly higher swelling power. These results confirm the value of wheat progenitor lines as sources of new starch properties for hexaploid wheat. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

18.
At the IPK Gatersleben a series of 85 bread wheat (T. aestivum)/goatgrass (Aegilops tauschii) introgression lines was developed recently. Based on the knowledge that chromosome 7D of this particular Ae. tauschii is a donor of resistance to septoria tritici blotch (Mycosphaerella graminicola), a sub-set of thirteen chromosome 7D introgression lines was investigated along with the susceptible recipient variety ‘Chinese Spring’ (CS) and the resistant donor line ‘CS (Syn 7D)’. The material was inoculated with two Argentinian isolates of the pathogen (IPO 92067 and IPO 93014) at both the seedlings (two leaf) and adult (tillering) stages at two locations over 2 years (2003, 2004). The resistance was effective against both isolates and at both developmental stages, and the resistance locus maps to the centromeric region of chromosome arm 7DS. On the basis of its relationship with the microsatellite marker Xgwm44, it is likely that the gene involved is Stb5. Stb5 is therefore apparently effective against M. graminicola isolates originating from both Europe and South America.  相似文献   

19.
Stripe rust, caused by Puccinia striiformis f. sp. tritici (PST), is one of the most important diseases of common wheat (Triticum aestivum L.). China has the largest stripe rust epidemic areas in the world and yield losses can be large. Aegilops tauschii Coss, the D-genome progenitor of common wheat, includes two subspecies, tauschii and strangulata (Eig) Tzvel. The ssp. strangulata accession AS2388 is highly resistant to the prevailing physiological races of PST in China, and possesses a single dominant gene for stripe rust resistance. In order to tag this gene, AS2388 was crossed with the highly susceptible ssp. tauschii accession AS87. The parents, F2 plants, and F2:3 families were tested at adult plant stage in field trials with six currently prevailing races. Simple sequence repeat (SSR) primers were used to identify molecular markers linked to the resistance gene. SSR markers Xwmc285 and Xwmc617 were linked to the resistance gene on chromosome arm 4DS flanking it at 1.7 and 34.6 cM, respectively. Based on the chromosomal location, this gene temporarily designated as YrAS2388 is probably novel. The resistance in Ae. tauschii AS2388 was partially expressed in two newly developed synthetic hexaploid backgrounds.  相似文献   

20.
Resistance to stripe rust (caused by Puccinia striiformis Westend.) of 34 Triticum turgidum L. var.durum, 278 T. tauschii, and 267 synthetic hexaploid wheats (T. turgidum x T. tauschii) was evaluated at the seedling stage in the greenhouse and at the adult-plant stage at two field locations. Mexican pathotype 14E14 was used in all studies. Seedling resistance, expressed as low infection type, was present in all three species. One hundred and twenty-eight (46%) accessions of T. tauschii, 8 (23%) of T. turgidum and 31 (12%) of synthetic hexaploid wheats were highly resistant as seedlings. In the field tests, resistance was evaluated by estimating area under disease progress curve (AUDPC). Synthetic hexaploid wheats showed a wide range of variability for disease responses in both greenhouse and field tests, indicating the presence of a number of genes for resistance. In general, genotypes with seedling resistance were also found to be resistant as adult plants. Genotypes, which were susceptible or intermediate as seedlings but resistant as adult plants, were present in both T. turgidum and the synthetic hexaploids. Resistances from either T. turgidum or T. tauschii or both were identified in the synthetic hexaploids in this study. These new sources of resistance could be incorporated into cultivated hexaploid wheats to increase the existing gene pool of resistance to stripe rust.  相似文献   

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