Microsatellite mapping of complementary genes for purple grain colour in bread wheat (Triticum aestivum) L.

Complementary genes for purple grain colour Pp1, Pp2, Pp3 (now designated Pp1, Pp3b, Pp3a, respectively) were mapped using crosses between purple-grained hexaploid wheats ‘Purple Feed’ – Pp1Pp1/Pp2Pp2 (Pp1Pp1/Pp3bPp3b), ‘Purple’ – Pp1Pp1/Pp3Pp3 (Pp1Pp1/Pp3aPp3a) with non-purple-grained cultivars ‘Novosibirskaya 67’ (‘N67’) and ‘Saratovskaya 29’ (‘S29’). The genes Pp2 (Pp3b) and Pp3 (Pp3a) were inherited as monofactorial dominant when purple-grained wheats were crossed to ‘N67’. Both were mapped in the centromeric region of the chromosome 2A. Therefore, they were suggested being different alleles at the same locus and designated Pp3a and Pp3b. In the crosses between purple-grained wheats and ‘S29’ a segregation ratio of 9 (purple) to 7 (non purple) was obtained suggesting a complementary interaction of two dominant genes, Pp1 and Pp3. To map Pp1 as a single gene, the influence of the other Pp gene was taken into consideration by determining the Pp3 genotype of the F₂ plants. The gene was mapped on chromosome 7BL, about 24 cM distal to the centromere. The Pp1gene was shown to be non allelic to the Rc-1 (red coleoptile) and Pc (purple culm) genes, contrary to what was previously suggested. The colouration caused by the Pp genes has no effect on pre-harvest sprouting.     

Telosomic mapping of the homoeologous genes for the long glume phenotype in tetraploid wheat

Triticum turgidum ssp. polonicum and T. ispahanicum were characterized by the long glume phenotype. P ₁ gene determines the long glume phenotype of T. polonicum, and locates on chromosome 7A. T. ispahanicum has shorter glume than T. polonicum and the long glumephenotype is determined by P ₂ gene located on chromosome 7B. In the present study, aneuploid stocks of `Langdon' durum wheat were used to map the genes, P ₁ and P ₂. P ₁ located on the long arms of chromosome 7A and its map distances from the centromere was 14.5 cM. On chromosome 7B, four loci located as cc (chocolate black chaff) – Pc (purple culm) – centromere – P ₂ – cn-BI (chlorina). P ₂ located on the long arms of chromosome 7B and its map distances from the centromere was 11.7 cM. It was suggested that a paralogous gene set conditions long glume phenotype in the homoeologous group 7 chromosomes. The P ₁ and P ₂ genes may be useful as genetic markers in tetraploid wheat.     

Genetic mapping of loci determining long glumes in the genus Triticum

Elongated glumes are present in thetetraploid wheat species T.polonicum, T. turanicum, T.durum convar. falcatum and in thehexaploid species T. petropavlovskyi.Inheritance of glume length was studiedwith the aim to map the respective lociusing wheat microsatellite markers. In T. polonicum and T. petropavlovskyiloci conferring long glume were mapped nearthe centromere on chromosome 7A. These twoloci are designated P-A ^pol 1 andP-A ^pet 1, respectively. It isshown that both are probably homoeoallelicto each other and to the P gene ofT. ispahanicum on chromosome 7B. The loci determining elongated glumes in T. turanicum and T. durum conv. falcatum are not homoeologous to the P loci in the centromeric region of thegroup 7 chromosomes.     

Comparative genetic mapping of homoeologous genes for the chlorina phenotype in the genus <Emphasis Type="Italic">Triticum</Emphasis>

Triticum monococcum L. (2n = 2x = 14, A^mA^m genome) is one of the most ancient of the domesticated crops in the Middle East, but it is not the ancestor of the A genome of durum wheat (T. durum Desf. 2n = 4x = 28, genomes BBAA) and bread wheat (T. aestivum L., 2n = 6x = 42, genomes BBAADD). It has been suggested that some differentiation has occurred between the A^m and A genomes. The chlorina mutants at the cn-A1 locus located on chromosome 7AL have been described in T. aestivum L. and T. durum, and a chlorina mutant has been found in T. monococcum. The aims of our study were to establish linkage maps for chlorina mutant genes on chromosome 7A of T. aestivum and T. durum and chromosome 7A^m of T. monococcum and to discuss the differentiation that has occurred between the A and A^m genomes. The chlorina mutant gene was found to be linked with Xhbg234 (8.0 cM) and Xgwm282 (4.3 cM) in F₂ plants of T. aestivum ANK-32A/T. petropavlovskyi k54716, and with Xbarc192 (19.5 cM) and Xgwm282 (12.0 cM) in F₂ plants of T. durum ANW5A-7A/T. carthlicum #521. Both the hexaploid and tetraploid wheats contained a common marker, Xgwm282. In F₂ lines of T. monococcum KT 3-21/T. sinskajae, the cn-A1 locus was bracketed by Xgwm748 (25.7 cM) and Xhbg412 (30.8 cM) on chromosome 7A^mL. The distal markers, Xhbg412, Xgwm282, and Xgwm332, were tightly linked in T. aestivum and T. durum. The common marker Xhbg412 indicated that the chlorina mutant genes are located on chromosome 7AL and that they are homoeologous mutations.     

Genetic control of long glume phenotype in tetraploid wheat derived from Triticum petropavlovskyi Udacz. et Migusch.

The Chinese wheat landrace, Xinjiang rice wheat (T. petropavlovskyi Udacz. et Migusch., 2n = 42), known as ‘Daosuimai’ or rice-head wheat is characterized by long glumes, and was found in the agricultural areas in the west part of Talimu basin, Xinjiang, China in 1948. The gene for long glume from T. petropavlovskyi was introduced into a line of spring durum wheat, LD222. The gene for long glume is located approximately46.8 cm from the cn-A1 locus, which controls the chlorinatrait. Significant deviation from a 3:1 in the F₂ of LDN7D(7A)/ANW5C confirmed that the long glume of T. petropavlovskyi can be controlled by a gene located on chromosome 7A. The gene locates approximately 12.4 ± 0.5 cM from the centromere on the long arm of 7A. It is considered that the gene for long glume from T. petropavlovskyi is an allele on the P ₁ locus, and it should be designated as P _1a. It is suggested that T. petropavlovskyi originated from either the natural hybrid between T. aestivum that has an awn-like appendage on the glume and T. polonicum or a natural point mutation of T. aestivum. This revised version was published online in August 2006 with corrections to the Cover Date.     

Interaction ofTriticum boeoticum cytoplasm and genomes ofT. aestivum andT. durum: Restoration of male fertility and plant vigor

Summary Male-sterile plants of reduced vigor were obtained by substitutingT. aestivum and/orT. durum genomes into the cytoplasm ofT. boeoticum, T. monococcum and amphidiploidT. boeoticum-A. squarrosa. Apparent segregation for plant vigor occurred even in advanced generations of the following backcross progenies:T. boeoticum/12*T. durum, T. monococcum/10*T. durum, T. boeoticum/2*T. durum//7*T. aestivum, amphidiploidT. boeoticum-A. squarrosa/6*T. durum and amphidiploidT. boeoticum-A. squarrosa/8*T. aestivum. Highly fertile F₁ hybrids of normal vigor were obtained from crosses of A lines of common wheat in the cytoplasm of amphidiploidT. boeoticum-A. squarrosa orT. timopheevi with R lines having male fertility restoring factors fromT. boeoticum, T. boeoticum-A. squarrosa andT. zhukovskyi. Apparently, vigor-genes complemented the male fertility restoring genes to produce fertile hybrids of normal plant vigor in the crosses amphidiploidT. boeoticum-A. squarrosa/6*T. aestivum, Chris//amphidiploidT. boeoticum-A. squarrosa/T. durum/T. aestivum, Chinese Spring, andT. zhukovskyi/3*T. aestivum, Justin F₈ R lines.Published with the approval of the Director, North Dakota State Agricultural Experiment Station, as Journal Article No. 231Associate Professors of Agronomy.     

Expression of 17 rye (Secale cereale L.) traits in a range of durum wheat (Triticum durum Desf.) and bread wheat (T. aestivum L.) genetic backgrounds

Summary Expression of 17 rye traits in 24 bread wheat x rye and 8 durum wheat x rye crosses was studied, using a self-compatible, homozygous, dwarf rye. Rye showed epistasis for hairiness on the peduncle in all the crosses of Triticum aestivum and T. durum wheats with rye. Dark greenness of leaves of rye was expressed in all the durum wheat x rye and in some of the bread wheat x rye crosses. Similarly, absence of auricle pubescence, a rye trait, was expressed in most of the durum wheat x rye crosses but not in the bread wheat x rye crosses, indicating the presence of inhibitors for these traits frequently on the D genome and rarely on the A and/or B genome of wheat. Most of the wide hybrids resembled rye fully or partially for intense waxy bloom on the leaf-sheath and for the absence of basal underdeveloped spikelets. Similarly, most of the amphihaploids resembled rye for the anthocyanin in the coleoptile, stem and node. The presence of some inhibitors on A and/or B genome of wheat was indicated in some of the wheat genotypes for the expression of rye traits viz. intense waxy bloom, anthocyanin in node and absence of basal underdeveloped spikelets. Enhancement in the level of expression of the intensity and length of bristles on the mid-rib of the glume of the hybrids might be due to wheat-rye interaction. Less number of florets/spikelet as in rye showed variable expression in different wheat backgrounds. Some other rye traits like absence of auricles, terminal spikelet and glume-awn were not expressed in the wheat background. The expression of some of the rye genes might have been influenced by their interaction with Triticum cytoplasm and/or the environment.     

Identification and genetic mapping of a powdery mildew resistance gene in wild emmer (<Emphasis Type="Italic">Triticum dicoccoides</Emphasis>) accession IW72 from Israel

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a devastating disease of wheat (Triticum aestivum) in China and worldwide, causing severe yield losses annually. Wild emmer (T. dicoccoides) accession IW72 collected from Israel is resistant to powdery mildew at the seedling and adult stages. Genetic analysis indicated that the resistance was controlled by a single dominant gene, temporarily designated MlIW72. The F₂ population and F₃ families derived from a hybrid between IW72 and susceptible durum wheat line Mo75 were used for molecular mapping of the resistance gene. MlIW72 was linked with SSR loci Xgwm344, Xcfa2040, Xcfa2240, Xcfa2257 and Xwmc525 on the long arm of chromosome 7A. In addition, two STS markers, MAG2185 (derived from RFLP marker PSR680) and MAG1759 (developed from EST CD452874), were mapped close to MlIW72. All these markers were physically located in the terminal bin 0.86–1.00 of 7AL. The chromosome location and genetic mapping results suggested that the powdery mildew resistance gene identified in wild emmer accession IW72 might be a new allele at the Pm1 locus or a new locus closely linked to Pm1.     

Chromosome locations of leaf rust resistance genes in selected tetraploid wheats through substitution lines

Langdon durum D-genome disomic substitution lines were used to study the chromosome locations of adult-plant leaf rust resistance genes identified from tetraploid wheat accessions. The accessions are 104 (Triticum turgidum subsp. dicoccum var. arras) and 127 (T. turgidum subsp. durum var. aestivum). The complete sets of the substitution lines were crossed as female parents with the accessions and F₁ double monosomic individuals selected at metaphase I. Segregating F₂ individuals were inoculated during the flag leaf stage with pathotype UVPrt2 of Puccinia triticina. The substitution analysis involving accession 104 showed that the gene for leaf rust resistance is located on chromosome 6B. The analysis with accession 127 indicated that chromosome 4A carries a gene for leaf rust resistance. The two novel genes are temporarily designated as Lrac104 and Lrac127, respectively from accessions 104 and 127.     

The inheritance and chromosomal location of a gene for long glume in durum wheat

Summary Several near-isogenic lines of durum wheat cv. LD222 have been developed. These include a near-isogenic line carrying gene P and designated P-LD222. The P gene from Triticum polonicum determines a long empty outer glume. The objective of this study was to determine the inheritance and chromosomal location of the P gene. To determine the inheritance, P-LD222 was crossed to two chlorina mutants and to a near-isogenic line for the purple culm trait, Pc-LD222. Linkage of the P gene with the mutated gene in chlorina mutant CDd6 indicated that the P gene was located on chromosome 7A. P-LD222 was also crossed with durum cultivar Langdon (LDN) and the LDN D genome substitution lines, LDN 7D(7A) and LDN 7D(7B). Segregation for the long glume trait in the F₂ of LDN/P-LD222 and LDN 7D(7B)/P-LD222 was normal (3:1) and indicated P gene was not on chromosome 7B. Significant deviation from a 3:1 in the F₂ of LDN 7D(7A)/P-LD222 confirmed the location of P on chromosome 7A, as indicated by the linkage analysis.     

The study of introgressive lines of Triticum aestivum × Aegilops speltoides by in situ and SSR analyses

Fluorescence in situ hybridization (FISH) with a genome‐specific repeat, Spelt1, and wheat simple sequence repeat (SSR) markers were used to analyse the chromosome constitution of two Triticum aestivum×Aegilops speltoides introgressive lines. The lines 170/98i and 178/98i carried one and two subtelomeric regions of Ae. speltoides (per haploid genome), respectively, marked by Spelt1 repeats according to FISH data. SSR analysis detected homoeologous substitution of wheat chromosome 7D with Ae. speltoides chromosome 7S in the lines 178/98i and 170/98i as well as the assumed terminal translocation in the short arm of chromosome 3A in the line 178/98i. Anthocyanin pigmentation of the coleoptiles was found in the lines 170/98i and 178/98i and resulted from the 7S (7D) substitution. It was demonstrated that Spelt1 could be effectively used for the rapid identification (without DNA isolation) of terminal translocations of T. aestivum×Ae. speltoides introgressive lines as well as for further analysis of the stability of the hybrid plants.     

Near-isogenic lines of durum wheat: their development and plant characteristics

Summary The effect of specific plant characteristics on the grain and biomass yield of durum wheat can be accurately determined by using isogenic lines, which, however, were not usually available. This study reported the effects of long glume, glaucousness, glume pubescence, black glume and purple culm on the yield and its associated characteristics in near-isogenic lines of durum wheat cv. LD222, which were developed by continuous backcrossing. The long glume trait which resulted in a large photosynthetic area did not enhance yield. Increased glume size associated with the P gene tended to increase the main culm dominance, characterized such as vigorous main culm and weak tillers, and plant height, but to reduce tillering and spike number. Consequently, grain yield and harvest index declined. Under the adequate water supplying condition of the present study, the glaucous trait was beneficial for grain yield. The trait of glume pubescence did not excert any significant effect on the yield related characteristics in the LD222 background. The traits of black glume and purple culm reduced the number of spikes per unit area and the number of kernels per unit area.     

Chromosome and chromosomal arm locations of genes for resistance to Septoria glume blotch in wheat cultivar Cotipora

Summary Septoria glume blotch, caused by Stagonospora nodorum, is an important disease of wheat (Triticum aestivum). Separate genetic mechanisms were found to control flag leaf and spike resistance. Genes for resistance to S. nodorum were located on different chromosomes in the few wheat cultivars studied. These studies only partially agree on the chromosome locations of gene in wheat for resistance to S. nodorum, and chromosomal arm locations of such genes are not known. The objectives of this study were to determine the chromosome and chromosomal arm locations of genes that significantly influence resistance to S. nodorum in wheat cultivar Cotipora. Monosomic analysis showed that flag leaf resistance was controlled by genes on chromosomes 3A, 4A, and 3B whereas the spike resistance was controlled by genes on chromosomes 3A, 4A, 7A, and 3B (P=0.01). Additionally, genes on chromosomes 6B and 5A influenced the susceptibility of the flag leaf and spike reactions, respectively (P=0.01). Telocentric analysis showed that genes on both arms of chromosome 3A, and the long arms of chromosomes 4A and 3B were involved in the flag leaf resistance whereas genes on both arms of chromosome 4A, the short arm of chromosome 3A, and the long arm of chromosome 3B conferred spike resistance.     

Genetic variation for tolerance or resistance to barley yellow dwarf virus in durum wheat

Summary One durum wheat line (Triticum durum), cv. 82PCD476, with useful BYDV tolerance or resistance, was singled out of 5 152 lines evaluated between 1979 and 1986. A few other lines such as cv. Boohai and cv. 12th IDSN 227, slightly inferior to cv. 82PCD476, also showed some value. With an hybrid of cv. 12th IDSN227 with the susceptible cv. 84PCY-S531, broad-sense heritability values of 0.37–0.41 were obtained for symptoms and a heritability value of 0.55 was obtained for the total weight of spikes. The weight of spikes was considered as a good indicator of wheat tolerance to BYDV. Although BYDV resistance or tolerance genes are not very common in durum wheat, sources of heritable resistance could be found. However, the resistance ofT. aestivum to BYDV was superior to the one found inT. durum.Cintribution no. 323     

Chromosome pairing in durum wheat haploids with and without <Emphasis Type="Italic">ph1b</Emphasis> of bread wheat

Durum or macaroni wheat (Triticum turgidum L., 2n = 4x = 28; AABB) is an allotetraploid with two related genomes, AA and BB, each with seven pairs of homologous chromosomes. Although the corresponding chromosomes of the two genomes are potentially capable of pairing with one another, the Ph1 (Pairing homoeologous) gene in the long arm of chromosome 5B permits pairing only between homologous partners. As a result of this Ph1-exercised disciplinary control, durum wheat and its successor, bread wheat (Triticum aestivum L., 2n = 6x = 42; AABBDD) show diploid-like chromosome pairing and hence disomic inheritance. The Ph mutants in the form of deletions are available in bread wheat (ph1b) and durum wheat (ph1c). Thus, ph1b-haploids of bread wheat and ph1c-haploids of durum wheat show extensive homoeologous pairing that has been shown by us and several others. Here we study the effect of ph1b allele of bread wheat on chromosome pairing in durum haploids, whereas we studied earlier the effect of ph1c allele in durum haploids that we synthesized. In durum wheat, the ph1b-haploids show much higher (49.4% of complement) pairing than the ph1c-haploids (38.6% of complement). Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the USDA or imply approval to the exclusion of other products that also may be suitable.     

Somatic Embryogenesis and Plant Regeneration from Tritordeum

Regeneration of plants by somatic embryogenesis from immature embryos of hexaploid tritordeum (AABBH^chH^ch, amphiploid Hordeum chilense×Triticum turgidum conv. durum) and durum wheat (Triticum tergidum) was induced on MS medium supplemented with different 2.4-D concentrations. Well-defined embryoids were formed with a high frequency on the scutellar callus from 1 or 2 weeks onwards and plantlets were developed from them. In the best cases from one single explant more than 100 plants could be obtained. Plants were also regenerated by somatic embryogenesis from inflorescences of Hordeum chilense×Triticum turgiditm conv. durum hybrid and its respective hexa-amphiploid. With regard to callus induction and regenerative ability, evident differences between hexa- and octoploid (H. chilense×T. aestivum) tritordeum were found, the latter showing a very low response.     

A sequence-specific PCR marker linked with Pm21 distinguishes chromosomes 6AS, 6BS, 6DS of Triticum aestivum and 6VS of Haynaldia villosa

To develop markers linked with Pm21 located on chromosome 6VS of Haynaldia villosa, a pair of primers (NAU/xibao15F and NAU/xibao15R) were designed according to the sequence of a serine/threonine kinase gene (Contig17515), whose expression was induced by Blumeria graminis and selected from the gene expression experiment using the Barley GeneChip. Using genomic DNA of various genetic stocks including the wheat variety ‘Yangmai#5’, H. villosa, Triticum durum–H. villosa amphiploid, seven T. aestivum–H. villosa addition lines involving chromosomes 1V–7V, the translocation line T6VS·6AL, and 21 nullisomic–tetrasomic and eight deletion lines of T. aestivum‘Chinese Spring’ as templates, four amplicons specific for 6VS, 6AS, 6BS and 6DS, respectively, were produced. F₂ individuals derived from the cross of ‘Yangmai#5’ × T6VS·6AL were analysed, and data indicate that NAU/xibao15₉₀₂ could be used as a co‐dominant marker for selecting Pm21 located on 6VS.     

Pleiotropic effects of the elongated glume gene P1 on grain and spikelet shape-related traits in tetraploid wheat

Wheat grain size and shape are associated not only with yield but also with product and milling quality. A subspecies of cultivated tetraploid wheat, Triticum turgidum ssp. polonicum, is characterized by elongated glumes. To elucidate morphological effects of the subspecies differentiation-related gene, we conducted QTL analysis for grain and spikelet shape using a mapping population between two tetraploid wheat subspecies, polonicum and durum. P1, the gene controlling the elongated glumes, was located on chromosome 7A, and the polonicum-type allele acted in an incomplete dominance manner to express the elongated glume phenotype. The polonicum allele of the P1 locus significantly affected not only glume length but also grain shape, spike shape, awn length and seed fertility in tetraploid wheat. The elongated glume phenotype was correlated with an increase in spike length, grain length and grain weight, and with a decrease in fertility, grain number and awn length. Thus, the subspecies differentiation-related gene in subspecies polonicum dramatically affects grain shape accompanied by alteration of spikelet shape in tetraploid wheat.