Utility of barley and wheat simple sequence repeat (SSR) markers for genetic analysis of Hordeum chilense and tritordeum

A selection of 36 wheat and 35 barley simple sequence repeat markers (SSRs) were studied for their utility in Hordeum chilense. Nineteen wheat and nineteen barley primer pairs amplified consistent H. chilense products. Nine wheat and two barley SSRs were polymorphic in a H. chilense mapping population, producing codominant markers that mapped to the expected homoeologous linkage groups in all but one case. Thirteen wheat and 10 barley primer pairs were suitable for studying the introgression of H. chilense into wheat because they amplified H. chilense products of distinct size. Analysis of wheat/H. chilense addition lines showed that the H. chilense products derived from the expected homoeologous linkage groups. The results showed that wheat and barley SSRs provide a valuable resource for the genetic characterization of H. chilense, tritordeums and derived introgression lines. Received: 20 November 2000 / Accepted: 12 April 2001     

Early evolution of the chromosomal structure of Triticum turgidum–Aegilops ovata amphiploids carrying and lacking the Ph1 gene

After two selfing generations of two different Triticum turgidum –Aegilops ovata amphiploids carrying the Ph1 gene, or lacking it (ph1c mutant), karyotypes of their offspring were scored by GISH (genomic in situ hybridization). On average, the chromosome number was lower than expected (56 chromosomes) on the basis of the parental constitutions (T. turgidum, AABB, 2n=4x=28; Ae. ovata, M^oM^oU^oU^o, 2n=4x=28). The lost chromosomes belonged to the wild Aegilops species. The two families differed greatly by their number of intergenomic translocations, also detected by GISH. The ph1c family showed nine translocations over 12 plants while only one translocation was observed in the Ph1 family. All exchanges involved either the M^o and U^o chromosomes or the M^o and wheat chromosomes, the size of the exchanged segment ranging from 3% to 36% of the total chromosome length. The results suggest an epistatic effect of the ph1c deletion over the genetic diploidizing system that operates in Ae. ovata since translocated chromosomes are most-likely derived from homoeologous recombination. The potential of these results for wheat breeding programmes is also considered. Received: 28 November 2000 / Accepted: 20 March 2001     

Spelt-specific alleles in HMW glutenin genes from modern and historical European spelt ( Triticum spelta L.)

A partial promoter region of the high-molecular weight (HMW) glutenin genes was studied in two wheat specimens, a 300 year-old spelt (Triticum spelta L.) and an approximately 250 year-old bread wheat (Triticum aestivum L.) from Switzerland. Sequences were compared to a recent Swiss landrace T. spelta ’Oberkulmer.’ The alleles from the historical bread wheat were most similar to those of modern T. aestivum cultivars, whereas in the historical and the recent spelt specific alleles were detected. Pairwise genetic distances up to 0.03 within 200 bp from the HMW Glu-A1-2, Glu-B1-1 and Glu-B1-2 alleles in spelt to the most-similar alleles from bread wheat suggest a polyphyletic origin. The spelt Glu-B1-1 allele, which was unlike the corresponding alleles in bread wheat, was closer related to an allele found in tetraploid wheat cultivars. The results are discussed in context of the origin of European spelt. Received: 22 July 2000 / Accepted: 27 April 2001     

Effects of loci on chromosomes 2 (2H) and 7 (5H) on developmental patterns in barley (Hordeum vulgare L.) under different photoperiod regimes

 Heading-date in cereals is the final result of a number of interacting characters that include vernalization requirement, photoperiod sensitivity, and earliness per se. Progress in developing adapted varieties may be achieved by determining the chromosomal locations of genes controlling these characters. Nineteen doubled-haploid (DH) lines from the Dicktoo×Morex mapping population were phenotyped in controlled- environment photoperiod experiments to determine the role of two previously detected QTLs on the developmental patterns of barley. The QTLs are hypothesised to represent the effects of the Ppd and Sh2 loci on chromosomes 2 (2H) and 7 (5H), respectively. Alleles at the Ppd locus were found to be vary in response to photoperiod duration. Vernalization had some effect on alleles at both loci. The presence of early and late- flowering transgressive segregants in this mapping population can be explained by interactions between the Ppd and Sh2 loci. The Ppd and Sh2 loci are hypothesised to be homoeologous with the Ppd and Vrn1 loci of wheat. Received: 1 August 1996 / Accepted: 15 November 1996     

Genetic mapping of QTL controlling tissue-culture response on chromosome 2B of wheat (Triticum aestivum L.) in relation to major genes and RFLP markers

 Three quantitative trait loci (QTL) for tissue- culture response (Tcr) were mapped on chromosome 2B of hexaploid wheat (Triticum aestivum L.) using single-chromosome recombinant lines. Tcr-B1 and Tcr-B2, affecting both green spots initiation and shoot regeneration, were mapped in relation to RFLP markers in the centromere region and on the short arm of chromosome 2B, linked to the photoperiod-response gene Ppd2. A third QTL (Tcr-B3), influencing regeneration only, was closely related to the disease resistance locus Yr7/Sr9g on the long arm of chromosome 2B. The homoeologous relationships to the tissue-culture response loci Qsr, Qcg and Shd of barley are discussed. A possible influence of the earliness per se genes of wheat and barley is suggested. Received: 30 August 1996 / Accepted: 15 November 1996     

Genetic Analysis of Anthocyanin Pigmentation of the Anthers and Culm in Common Wheat

Anthocyanin pigmentation of various organs develops during plant ontogeny in response to adverse and damaging abiotic and biotic stressors (environmental factors). Using the monosome method, the genes responsible for anther and culm anthocyanin pigmentation (Pan1 and Pc2, respectively) were localized to 7D chromosome in introgressive lines from crosses between common wheat Triticum aestivum L. and the species Triticum timopheevii Zhuk. Genetic analysis of ten common wheat genotypes using testers carrying genes Pan1, Pc1 and Pc2 showed that these genotypes contained Pan1 and Pc2 genes. Visual examination of plants from 70 and 76 varieties of respectively winter and spring common wheat revealed anthocyanin pigmentation of anthers and culms in 36 varieties. Pan1 and Pc2 genes were presumably introduced into common wheat from Aegilops tauschii (Eig.) Tzvel., a donor of the D genome.     

RFLP-based mapping of three mutant loci in rye (Secale cereale L.) and their relation to homoeologous loci within the Gramineae

 Three mutant loci of rye determining absence of ligules (al), waxless plant (wa1) and waxy endosperm (Wx) characters were mapped in a single F₂ population, comprising 84 individual plants. The three loci could be clearly tagged in relation to 7 (al on chromosome 2R), 4 (wa1 on chromosome 7R) or 6 (Wx on chromosome 4R) RFLP markers. The mapping data are compared with existing data for homoeologous regions containing equivalent mutants of wheat, barley, rice and maize. It is shown that the loci analysed are highly conserved across the cereal species, including rye. Received: 14 March 1997 / Accepted: 21 March 1997     

Molecular mapping of the photoperiod response gene ea7 in barley

 The gene ea ₇ determining photoperiod insensitivity under short day length was mapped on the short arm of chromosome 6H near the centromere. The gene was linked to the two flanking markers Xmwg2264 and Xmwg916 by 6.7 and 13.0 cM, respectively. Compared to Ppd-H1 (chromosome 2H) and Ppd-H2 (chromosome 1H), ea ₇ determines the strongest effect on flowering time with 55 and 18 days difference compared to photoperiod sensitive genotypes grown under short and long photoperiods, respectively. Allelic and homoeologous relationships to major genes and quantitative trait loci controlling flowering time in barley and wheat are discussed. Received: 10 March 1998 / Accepted: 7 April 1998     

Is the <Emphasis Type="Italic">Mnr</Emphasis> locus of Triticeae species the same as the <Emphasis Type="Italic">Ndh</Emphasis> and <Emphasis Type="Italic">Dia</Emphasis> loci?

The menadione reductase (MNR), the nicotinamide adenine dinucleotide dehydrogenase (NDH) and diaphorase (DIA) isozymes were studied in the allohexaploid Triticum aestivum cv ”Chinese Spring” and in five diploid Triticeae species. The Mnr1, Ndh3 and Dia1 loci were located on the chromosome arms 3AL, 3BL and 3DL of T. aestivum, respectively. These loci were also located on the 3H chromosome of Hordeum vulgare cv ”Betzes”, the 3L chromosome of Aegilops longissima and the 6RL chromosome arm of Secale cereale cv ”Imperial”. The chromosomal location results together with the segregation studies support a tetrameric behaviour of the MNR1, NDH3 and DIA1 isozymes. The Ndh1 and Dia3 loci were located on homoeologous group 4 showing a monomeric behaviour. The chromosomal locations and linkage data of the Mnr, Ndh and Dia loci suggest that Mnr1=Ndh3=Dia1; Ndh1=Dia3 and Ndh2=Dia2. Received: 3 June 2001 / Accepted: 11 July 2001     

Genetic analysis of anthocyanin of the anthers and culm pigmentation in common wheat

Anthocyanin pigmentation of various organs develops during plant ontogeny in response to adverse and damaging abiotic and biotic stressors (environmental factors). Using the monosome method, the genes responsible for anther and culm anthocyanin pigmentation (Pan1 and Pc2, respectively) were localized to 7D chromosome in introgressive lines from crosses between common wheat Triticum aestivum L. and the species Triticum timopheevii Zhuk. Genetic analysis of ten common wheat genotypes using testers carrying genes Pan1, Pn1, and Pn2 showed that these genotypes contained Pan1 and Pn2 genes. Visual examination of plants from 70 and 76 varieties of respectively winter and spring common wheat revealed anthocyanin pigmentation of anthers and culms in 36 varieties. Pan1 and Pn2 genes were presumably introduced into common wheat from Aegilops tauschii (Fig.) Tzvel., a donor of the D genome.     

Linkage mapping of mutant loci in rye (Secale cereale L.)

Eight mutant loci determining the traits waxy plant (w and wa1), brown culm (cb), multiple pistils (mp), weak plant with reduced plant height (np), monoculm growth habit (mc), compactum growth habit (ct3) and anthocyaninless (an) were mapped on rye chromosomes 4R (w, np), 6R (cb, mc) and 7R (mp, wa1, ct3, an). For five mutants (w, wa1, cb, mp, np) molecular and biochemical markers were applied, whereas for mc, ct3 and an a classical linkage analysis was performed. Furthermore, it could be demonstrated that homoeologous relationships exist between most of the mapped rye loci and comparable mutants in wheat and barley. It was confirmed not only that genes controlling fundamental aspects of plant biology are highly conserved across the Triticeae species but so also were many mutant loci. Received: 19 June 2000 / Accepted: 18 October 2000     

Detection of loci controlling seed dormancy on group 4 chromosomes of wheat and comparative mapping with rice and barley genomes

Three quantitative trait loci (QTLs) controlling seed dormancy were detected on group 4 chromosomes of wheat (Triticum aestivum L.) using 119 doubled haploid lines (DHLs) derived from a cross between AC Domain and Haruyutaka. A major QTL, designated QPhs.ocs-4A.1, was identified within the marker interval between Xcdo795 and Xpsr115 in the proximal region of the long arm of chromosome 4A. Two minor QTLs, QPhs.ocs-4B.2 on 4B and QPhs.ocs-4D.2 on 4D, were flanked by common markers, Xbcd1431.1 and Xbcd1431.2 in the terminal region of the long arms, suggesting a homoeologous relationship. These three QTLs explained more than 80% of the total phenotypic variance in seed dormancy of DHLs grown in the field and under glasshouse conditions. The AC Domain alleles at the three QTLs contributed to increasing seed dormancy. Comparative maps across wheat, barley and rice demonstrated the possibility of a homoeologous relationship between QPhs.ocs-4A.1 and the barley gene SD4, while no significant effects of the chromosome regions of wheat and barley orthologous to rice chromosome 3 region carrying a major seed dormancy QTL were detected. Received: 5 June 2000 / Accepted: 31 August 2000     

Developmental and environmental regulation of anthocyanin pigmentation in wheat tissues transformed with anthocyanin regulatory genes

Summary Cell autonomous anthocyanin pigmentation, produced by the anthocyanin regulatory genes B and C1 controlled by the constitutive CaMV35s promoter (pBC1-7), was used to optimize biolistic gene delivery into embryogenic wheat (Triticum aestivum L. cv ‘Chris’) scutellum cultures. Intensely pigmented callus cells were observed 24 h postbombardment but these cells did not continue to divide and were developmentally terminal. A population of nonexpressing cells generated transgenic sectors which showed light-dependent anthocyanin pigmentation. Anthocyanin pigmentation was suppressed in regenerating shoot cultures but reverted to light-dependent production in the pericarp of developing seeds. Similarly, following microtargeted gene delivery into apical meristems, anthocyanin production was developmentally suppressed in leaf base meristems but prominent anthocyanin sectors developed in mature tissues beyond this region and persisted throughout leaf growth. In three developmental situations, callus proliferation, plant regeneration, and leaf growth, perpetuation of cells with anthocyanin regulator genes under the control of constitutive promoters was dependent on a higher level of regulation to suppress pigmentation at developmentally sensitive stages of meristematic activity. These findings provide additional evidence that the anthocyanin regulatory genes may be responsive to a variety of developmental and environmental stimuli. Present address: Genetics & Plant Breeding Department, G. B. Pant University of Agriculture Technology, Pantnagar, U.P., India, 263145.     

Comparative RFLP mapping of the chlorotoluron resistance gene (Su1) in cultivated wheat (Triticum aestivum) and wild wheat (Triticum dicoccoides)

Chlorotoluron is a selective phenylurea herbicide widely used for broad-leaved and annual grass weed control in cereals. Variation in the response to chlorotoluron (CT) was found in both hexaploid bread wheat (Triticum aestivum L.) and wild tetraploid wheat (Triticum dicoccoides KöRN.). Here, we describe the comparative mapping of the CT resistance gene (Su1) on chromosome 6B in bread and wild wheat using RFLP markers. In bread wheat, mapping was based on 58 F₄ single-seed descent (SSD) plants of the cross between a genotype sensitive to chlorotoluron, ‘Chinese Spring’ (CS), and a resistant derivative, the single chromosome substitution line, CS (‘Cappele-Desprez’ 6B) [CS (CAP6B). In T dicoccoides, mapping was based on 37 F₂ plants obtained from the cross between the CT-susceptible accession B-7 and the resistant accession B-35. Nine RFLP probes spanning the centromere were chosen for mapping. In bread wheat Su1 was found to be linked to α-Amy-1 (9.84 cM) and Xpsr371 (5.2 cM), both on the long arm of 6B, and Nor2 (2.74 cM) on the short arm. In wild wheat the most probable linkage map was Nor2-Xpsr312-Su1-Pgk2, and the genetic distances between the genes were 24.8cM, 5.3cM, and 6.8cM, respectively. These results along with other published map data indicate that the linear order of the genes is similar to that found in T. aestivum. The results of this study also show that the Su1 gene for differential response to chlorotoluron has evolved prior to the domestication of cultivated wheat and not in response to the development and use of chemicals.     

Homoeologous relationships of Aegilops speltoides chromosomes to bread wheat

 Homoeologous pairing at metaphase I was analysed in the standard-type, ph2b and ph1b hybrids of Triticum aestivum (AABBDD) and Aegilops speltoides (SS). Data from relative pairing affinities were used to predict homoeologous relationships of Ae. speltoides chromosomes to wheat. Chromosomes of both species, and their arms, were identified by C-banding. The Ae. speltoides genotype carried genes that induced a high level of homoeologous pairing in the three types of hybrids analyzed. All arms of the seven chromosomes of the S genome showed normal homoeologous pairing, which implies that no apparent chromosome rearrangements occurred in the evolution of Ae. speltoides relative to wheat. A pattern of preferential pairing of two types, A-D and B-S, confirmed that the S genome is very closely related to the B genome of wheat. Although this pairing pattern was also reported in hybrids of wheat with Ae. longissima and Ae. sharonensis, a different behaviour was found in group 5 chromosomes. In the hybrids of Ae. speltoides, chromosome 5B-5S pairing was much more frequent than 5D-5S, while these chromosome associations reached similar frequencies in the hybrids of Ae. longissima and Ae. sharonensis. These results are in agreement with the hypothesis that the B genome of wheat is derived from Ae. speltoides. Received: 8 January 1998 / Accepted: 4 February 1998     

Mapping of esterase loci in <Emphasis Type="Italic">Aegilops uniaristata</Emphasis> and homoeologous group 3 chromosomes of wheat

This study was planned to identify the chromosomal location of esterase loci in wheat (Triticum aestivum), in comparison to Aegilops uniaristata, using wheat Ae. uniaristata disomic addition and translocation lines. Two loci (Est-N1 and Est-N8) were identified on 3N chromosome of Ae. uniaristata and their probable homoeoloci were, for the first time, mapped close to three RFLP probes (Xpsr56, Xpsr394, and Xpsr1196) on homoeologous group 3 wheat chromosomes.     

Genetics and molecular mapping of a male fertility restoration locus (Rfg1) in rye (Secale cereale L.)

 A gene determining the restoration of cytoplasmic genic male sterility (CMS) caused by the Gülzow (G)-type cytoplasm was mapped by analyzing an F₂ and F₃ population comprising 140 and 133 individual plants, respectively. The target gene, designated Rfg1, was mapped on chromosome 4RL distally to three RFLP (Xpsr119, Xpsr167, Xpsr899) and four RAPD (XP01, XAP05, XR11, XS10) loci. Xpsr167 and Xpsr899 are known to be located on the segment of chromosome 4RL which was ancestrally translocated and is homoeologous to the distal end of other Triticeae 6S chromosomes. It is suggested that Rfg1 may be allelic to the gene determining the restoration of rye CMS caused by the Pampa (P) cytoplasm (chromosome 4RL) and to Rfc4 that on rye addition lines of chromosome 4RL restores male fertility of hexaploid wheat with T. timopheevi cytoplasm. Homoeoallelism to two loci for cytoplasmic-male-sterility restoration on chromosomes 6AS and 6BS in hexaploid wheat is also suggested. Received: 1 December 1997 / Accepted: 10 February 1998     

Characterisation of type-I thionin loci from the A, B, D and R genomes of wheat and rye

 DNA sequences encoding type-I thionins were isolated from Triticum aestivum L. cv ‘Chinese Spring’ using PCR with consensus primers. Blunt-end cloning, sequencing and PCR-based chromosome assignment of these fragments uncovered the three orthologous sequences corresponding to the single-copy genes at the Pur-1 loci on each of the group-1 chromosomes. Comparison with two previously published cDNA sequences revealed the presence of two introns that contain most of the polymorphic nucleotide sites. The observed orthologous DNA sequence variation among Pur-1 loci, encoded by each of the A, B and D genomes, enabled us to establish interlocus relationships and to construct locus-specific primer sets. Analogously, the Pur-R1 sequence from rye was isolated, and a locus-specific primer pair was constructed as well. Hence, four locus-specific primer sets are now available as molecular markers for the homoeologous 1AL, 1BL, 1DL and 1RL chromosome arms. Amplification from several diploid and tetraploid wheat species showed that the primers can be used as molecular tools for studying wheat phylogeny. Received: 30 January 1997 / Accepted: 23 June 1997     

Identification of RAPD markers for 11 Hessian fly resistance genes in wheat

 The pyramiding of genes that confer race- or biotype-specific resistance has become increasingly attractive as a breeding strategy now that DNA-based marker-assisted selection is feasible. Our objective here was to identify DNA markers closely linked to genes in wheat (Triticum aestivum L.) that condition resistance to Hessian fly [Mayetiola destructor (Say)]. We used a set of near-isogenic wheat lines, each carrying a resistance gene at 1 of 11 loci (H3, H5, H6, H9, H10, H11, H12, H13, H14, H16 or H17) and developed by backcrossing to the Hessian fly-susceptible wheat cultivar ‘Newton’. Using genomic DNA of these 11 lines and ‘Newton’, we have identified 18 randomly amplified polymorphic DNA (RAPD) markers linked to the 11 resistance genes. Seven of these markers were identified by denaturing gradient gel electrophoresis and the others by agarose gel electrophoresis. We confirmed linkage to the Hessian fly resistance loci by cosegregation analysis in F₂ populations of 50–120 plants for each different gene. Several of the DNA markers were used to determine the presence/absence of specific Hessian fly resistance genes in resistant wheat lines that have 1 or possibly multiple genes for resistance. The use of RAPD markers presents a valuable strategy for selection of single and combined Hessian fly resistance genes in wheat improvement. Received: 20 March 1996 / Accepted: 6 September 1996