Location of genes coding isozyme markers on Aegilops umbellulata chromosomes adds data on homoeology among Triticeae chromosomes

Summary Zymogram analysis was used to identify the Aegilops umbellulata chromosomes that carry the structural genes for particular isozymes. Wheat, Aegilops and wheat-Aegilops hybrid derivative lines (which contained identified Aegilops chromosomes) were tested by gel electrophoresis for isozymes of particular enzymes. It was found that Aegilops chromosome A (nomenclature according to G. Kimber 1967) carries a structural gene for 6-phosphogluconate dehydrogenase, Aegilops chromosome B carries structural genes for glucose phosphate isomerase and phosphoglucose mutase, Aegilops chromosome D carries genes for leaf peroxidases, Aegilops chromosome E carries structural genes for endosperm peroxidases, acid phosphatases and leaf esterases, Aegilops chromosome F carries a gene for embryo plus scutellum peroxidases and Aegilops chromosome G carries structural genes for endosperm alkaline phosphatases, leaf alkaline phosphatases and leaf esterases. The results obtained indicate that chromosome B is partially homoeologous of the wheat chromosomes of group 1 and 4, and chromosome E is partially homoeologous of wheat chromosomes of groups 7 and 4. Circumstantial evidence is also provided about the possible association between chromosomes C, D and A of A. umbellulata respectively with chromosomes 5, 2 and 1 of wheat.     

Genetic control of 6-phosphogluconate dehydrogenase (6-PGD) isozymes in cultivated wheat and rye

Summary The 6-phosphogluconate dehydrogenase (6-PGD) zymogram phenotypes of wheat, rye and their aneuploid derivatives were determined. Two genes involved in the production of 6-PGD isozymes were located on chromosome arms CRL (4 RL) and FRL (6 RL) of Imperial rye. On the basis of differential interactions between wheat and rye chromosomes, evidence was obtained that genes located on chromosomes 6 A, 6 BL and 7 BL control 6-PGD isozyme activities in Chinese Spring wheat. The wheat and rye 6-PGD zymogram phenotypes were indicative of homoeologous relationships between rye chromosome 6 RL to wheat chromosomes of group 6, and rye chromosome 4 RL to wheat chromosomes of group 7.     

Location of β-amylase sequences in wheat and its relatives

Summary A -amylase cDNA clone isolated from barley has been used to locate -amylase encoding sequences on wheat, rye, and Aegilops umbellulata chromosomes by hybridisation to restriction endonuclease digested DNA obtained from wheat aneuploid and wheat-alien addition lines. Structural genes were identified on homoeologous group 4 and 5 chromosomes, confirming the results of isozyme studies. In addition, a further set of structural genes was found on homoeologous group 2 chromosomes. It is proposed that there are two homoeoallelic series, -Amy-1 on group 4 or 5 chromosomes, and -Amy-2 on group 2 chromosomes. Evidence is presented that each locus contains one or two -amylase structural genes, and it is suggested that the large number of isozymes seen upon IEF are due to post-translational modifications.     

Disomic Thinopyrum intermedium addition lines in wheat with barley yellow dwarf virus resistance and with rust resistances.

Zhong 5 is a partial amphiploid (2n = 56) between Triticum aestivum (2n = 42) and Thinopyrum intermedium (2n = 42) carrying all the chromosomes of wheat and seven pairs of chromosomes from Th. intermedium. Following further backcrossing to wheat, six independent stable 2n = 44 lines were obtained representing 4 disomic chromosome addition lines. One chromosome confers barley yellow dwarf virus (BYDV) resistance, whereas two other chromosomes carry leaf and stem rust resistance; one of the latter also confers stripe rust resistance. Using RFLP and isozyme markers we have shown that the extra chromosome in the Zhong 5-derived BYDV resistant disomic addition lines (Z1, Z2, or Z6) belongs to the homoeologous group 2. It therefore carries a different locus to the BYDV resistant group 7 addition, L1, described previously. The leaf, stem, and stripe rust resistant line (Z4) carries an added group 7 chromosome. The line Z3 has neither BYDV nor rust resistance, is not a group 2 or group 7 addition, and is probably a group 1 addition. The line Z5 is leaf and stem rust resistant, is not stripe rust resistant, and its homoeology remains unknown.     

Chromosomal location of genes controlling seed proteins in species related to wheat

Summary The seed proteins of Chinese Spring wheat stocks which possess single chromosomes from other plant species related to wheat have been separated by gel electrophoresis in the presence of sodium dodecyl sulphate. Marker protein bands have been detected for both arms of barley chromosome 5, chromosome E (= 1R) and B (= 2R) of rye, chromosomes A,B (= 1C^u) and C (= 5C^u) of Aegilops umbellulata and chromosomes I and III of Agropyron elongatum. These studies, and previous findings, indicate that chromosome 5 of barley, chromosome 1R of rye, chromosome I of Ag. elongatum and possibly chromosome 1C^u of Ae. umbellulata are similar to chromosomes 1A, 1B and 1D in hexaploid wheat in that they carry genes controlling prolamins on their short arms and genes controlling high-molecular-weight (apparent molecular weight greater than 86,000) seed protein species on their long arms. These findings support the idea that all these chromosomes are derived from a common ancestral chromosome and that they have maintained their integrity since their derivation from that ancestral chromosome.     

Chromosomal location of isozyme and seed storage protein genes in Dasypyrum villosum (L.) Candargy

Summary The zymogram phenotypes of glucose-phosphate isomerase (GPI), alcohol dehydrogenase-1 (ADH-1), glutamate oxaloacetate transaminase (GOT), superoxide dismutase (SOD), lipoxygenase (LPX), esterase (EST) and the banding patterns of gliadin and glutenin seed storage proteins were determined for Triticum aestivum cv. Chinese Spring (CS), Dasypyrum villosum, the octoploid amphiploid T. aestivum cv. Chinese Spring D. villosum (CS × v) (2n=8x=56; AABBDDVV), and for five CS-D. villosum disomic addition lines. The genes Gpi-V1, Adh-V1, Got-V2, and Sod-V2 coding for GPI-1, ADH-1, GOT-2, and SOD-2 isozymes were located in D. villosum on chromosome 1V, 4V, 6V, and 7V, respectively. Genes coding for gliadin- and glutenin-like subunits are located in D. villosum chromosomes 1V. There are no direct evidence for chromosomal location of genes coding for GOT-3, EST-1 and LPX-2 isozymes. The linkage between genes coding for glutenin-like proteins and GPI-1 isozymes in chromosome 1V is evidence of homoeology between chromosome 1V and the chromosomes of homoeologous group 1 in wheat.Research supported by the National Research Council (Italy) and National Science Foundation (USA). International cooperative project, Grant No. 85.01504.06 (CNR)     

Characterization and genetic control of the prolamins of Haynaldia villosa: Relationship to cultivated species of the Triticeae (rye,wheat, and barley)

Haynaldia villosa is a wild grass of the tribe Triticeae, other members of which include the cultivated cereals barley, rye, and wheat. We have made an electrophoretic and chemical characterization of the major seed storage proteins (prolamins) of H. villosa and determined the chromosomal locations of the structural genes for some components using the available wheat/H. villosa chromosome addition lines. As in wheat, barley, and rye, groups of high molecular weight (polymeric), sulfur-poor (monomeric), and sulfur-rich (monomeric -type and polymeric) prolamins can be recognized. Most of the components are encoded by genes on chromosome 1 Ha, which is homologous with the chromosomes controlling many of the prolamins in wheat and rye and all of those in barley. In addition, H. villosa also contains -type sulfur-rich prolamins, previously detected only in wheat and its close relatives. These may be encoded by genes on chromosome 6Ha, which is homologous with the group 6 chromosomes that control the -type gliadins of wheat. Despite the proposed close relationship between Haynaldia and ryes, no evidence was found for the presence of proteins closely related to the M _r 75,000 -secalins which are characteristic of wild and cultivated species of Secale.     

The chromosomal location of peroxidase isozymes of the wheat kernel

Summary The analysis of the individual parts of the Triticum aestivum L. kernel yields a total of 11 peroxidase isozymes: m, n, a, c, d₁, d, d₂, e, f, g and h (in order from faster to slower migration). Isozymes a, c and d are found in the endosperm (Ed) and seed coats (C), while m, n, d₁, d₂, e, f, g and h are peculiar to the embryo and scutellum (E + S). The use of the nullitetrasomic and ditellosomic series of Chinese Spring wheat allows peroxidase isozymes to be associated with specific chromosome arms. Isozymes a, c and d (Ed) are associated with chromosome arms 7D^S, 4B^L and 7A^S; whereas isozymes m, d₂, e and f are associated with chromosome arms 3D^S, 3B^L, 3D^L and 3D^L, respecitvely. Thus, the E + S isozymes are associated with homoeology group 3 and the Ed isozymes with homoeology groups 7 (a and d isozymes) or 4 (c isozymes).     

The inheritance of seed peroxidases of wheat and rye: further data

Summary Further data on the inheritance of seed peroxidases of hexaploid wheat (Triticum aestivum L.) and rye (Secale cereale L.) have been obtained from the genetic analysis of several progenies of both species. Additional data on the inheritance and the chromosomal location and linkage have been obtained for peroxidases of wheat embryo and rye endosperm. The general presence of null alleles in peroxidase loci has been confirmed in both species. In addition to simple monogenic inheritance, epistatic segregations have been observed in both species. These epistatic segregations again suggest the presence of regulatory genes controlling the expression of individual peroxidases in both species and also the existence of several duplicate homoeologous genes in wheat. Known linkage relationships have been confirmed and new ones are indicated. Loci for embryo wheat peroxidases seem to be in chromosomes of the homoeology group 3. The rye endosperm ones should be in chromosome 7R, although it is hypothesized that a duplication of gene EPer1 is located in chromosomes 4R and 7R.     

Genetics of CM-proteins (A-hordeins) in barley

Summary The CM-proteins, which are the main components of the A-hordeins, include four previously described proteins (CMa-1, CMb-1, CMc-1, CMd-1), plus a new one, CMe-1, which has been tentatively included in this group on the basis of its solubility properties and electrophoretic mobility. The variability of the five proteins has been investigated among 38 Hordeum vulgare cultivars and 17 H. spontaneum accessions. Proteins CMa-1, CMc-1 and CMd-1 were invariant within the cultivated species; CMd was also invariant in the wild one. The inheritance of variants CMb-1/CMb-2 and CMe-1/CMe-2,2 was studied in a cross H. spontaneum x H. vulgare. The first two proteins were inherited as codominantly expressed allelic variations of a single mendelian gene. Components CMe-2,2 were jointly inherited and codominantly expressed with respect to CMe-1. Gene CMb and gene(s) CMe were found to be unlinked. The chromosomal locations of genes encoding CM-proteins were investigated using wheat-barley addition lines. Genes CMa and CMc were associated with chromosome 1, and genes CMb and CMd with chromosome 4. These gene locations further support the proposed homoeology of chromosomes 1 and 4 of barley with chromosomes groups 7 and 4 of wheat, respectively. Gene(s) CMe has been assigned to chromosome 3 of barley. The accumulation of protein CMe-1 is totally blocked in the high lysine mutant Riso 1508 and partially so in the high lysine barley Hiproly.     

Extent of genetic variability of endosperm esterases in Triticum aestivum L. 2n=6x=42

Summary Genetic variability of endosperm esterase has been studied in 42 cultivars of Triticum aestivum L. 2n=6x=42. Different techniques, including sequential electrophoresis and electrofocusing, have been used with various substrates and esterase inhibitors. The electrophoretic patterns in each cultivar are described. Chromosomal location using the nullitetrasomic and ditelosomic lines of Chinese Spring was carried out in order to relate and/or locate the esterase genes to specific chromosomes. Most of the esterase isozymes located were in the long arm of the chromosomes of the homoeology group 3; but we have found six located in the short arms, five of them in the chromosome 3AS and one in the 3DS. This location increases the number of esterase genes described, because no esterase genes had been described so far in short arms of chromosomes of the homoeology group 3. The genetic control is discussed and, according to our results, between 12 and 15 loci, organized in five compound loci, control the endosperm esterases in wheat. Also one modifier gene modifying the mobility of two esterase bands and present in all the cultivars studied is postulated.This work was supported by a personal grant (L. Rebordinos) from the P.F.P.I. and by an institutional grant from the C.A.I.C.Y.T. (PB85-0153)     

Molecular and chromosomal organization of DNA sequences coding for the ribosomal RNAs in cereals

The chromosomal locations of ribosomal DNA in wheat, rye and barley have been determined by in situ hybridization using high specific activity ¹²⁵I-rRNA. The 18S-5.8S-26S rRNA gene repeat units in hexaploid wheat (cv. Chinese Spring) are on chromosomes 1B, 6B and 5D. In rye (cv. Imperial) the repeat units occur at a single site on chromosome 1R(E), while in barley (cv. Clipper) they are on both the chromosomes (6 and 7) which show secondary constrictions. In wheat and rye the major 5S RNA gene sites are close to the cytological secondary constrictions where the 18S-5.8S-26S repeating units are found, but in barley the site is on a chromosome not carrying the other rDNA sequences. — Restriction enzyme and R-loop analyses showed the 18S-5.8S-26S repeating units to be approximately 9.5 kb long in wheat, 9.0 kb in rye and barley to have two repeat lengths of 9.5 kb and 10 kb. Electron microscopic and restriction enzyme data suggest that the two barley forms may not be interpersed. Digestion with EcoR1 gave similar patterns in the three species, with a single site in the 26S gene. Bam H1 digestion detected heterogeneity in the spacer regions of the two different repeats in barley, while in rye and wheat heterogeneity was shown within the 26S coding sequence by an absence of an effective Bam H1 site in some repeat units. EcoR1 and Bam H1 restriction sites have been mapped in each species. — The repeat unit of the 5S RNA genes was approximately 0.5 kb in wheat and rye and heterogeneity was evident. The analysis of the 5S RNA genes emphasizes the homoeology between chromosomes 1B of wheat and 1R of rye since both have these genes in the same position relative to the secondary constriction. In barley we did not find a dominant monomer repeat unit for the 5S genes.     

Development of a wheat single gene FISH map for analyzing homoeologous relationship and chromosomal rearrangements within the Triticeae

Key message

A cytogenetic map of wheat was constructed using FISH with cDNA probes. FISH markers detected homoeology and chromosomal rearrangements of wild relatives, an important source of genes for wheat improvement.

Abstract

To transfer agronomically important genes from wild relatives to bread wheat (Triticum aestivum L., 2n = 6x = 42, AABBDD) by induced homoeologous recombination, it is important to know the chromosomal relationships of the species involved. Fluorescence in situ hybridization (FISH) can be used to study chromosome structure. The genomes of allohexaploid bread wheat and other species from the Triticeae tribe are colinear to some extent, i.e., composed of homoeoloci at similar positions along the chromosomes, and with genic regions being highly conserved. To develop cytogenetic markers specific for genic regions of wheat homoeologs, we selected more than 60 full-length wheat cDNAs using BLAST against mapped expressed sequence tags and used them as FISH probes. Most probes produced signals on all three homoeologous chromosomes at the expected positions. We developed a wheat physical map with several cDNA markers located on each of the 14 homoeologous chromosome arms. The FISH markers confirmed chromosome rearrangements within wheat genomes and were successfully used to study chromosome structure and homoeology in wild Triticeae species. FISH analysis detected 1U-6U chromosome translocation in the genome of Aegilops umbellulata, showed colinearity between chromosome A of Ae. caudata and group-1 wheat chromosomes, and between chromosome arm 7S#3L of Thinopyrum intermedium and the long arm of the group-7 wheat chromosomes.     

Development of a complete set of wheat–barley group-7 Robertsonian translocation chromosomes conferring an increased content of β-glucan

Key message

A complete set of six compensating Robertsonian translocation chromosomes involving barley chromosome 7H and three chromosomes of hexaploid wheat was produced. Grain β-glucan content increased in lines containing 7HL.

Abstract

Many valuable genes for agronomic performance, disease resistance and increased yield have been transferred from relative species to wheat (Triticum aestivum L.) through whole-arm Robertsonian translocations (RobT). Although of a great value, the sets of available translocations from barley (Hordeum vulgare L.) are limited. Here, we present the production of a complete set of six compensating RobT chromosomes involving barley chromosome 7H and three group-7 chromosomes of wheat. The barley group-7 long-arm RobTs had a higher grain β-glucan content compared to the wheat control. The β-glucan levels varied depending on the temperature and were higher under hot conditions. Implicated in this increase, the barley cellulose synthase-like F6 gene (CslF6) responsible for β-glucan synthesis was physically mapped near the centromere in the long arm of barley chromosome 7H. Likewise, wheat CslF6 homoeologs were mapped near the centromere in the long arms of all group-7 wheat chromosomes. With the set of novel wheat–barley translocations, we demonstrate a valuable increase of β-glucan, along with a resource of genetic stocks that are likely to carry many other important genes from barley into wheat.

     

Production of wheat-barley recombinant chromosomes through induced homoeologous pairing

Summary Sears' phlb mutant was used successfully for the first time to induce pairing and recombination between specific barley chromosomes and their wheat homoeologues. Pairing was induced in specially constructed genetic stocks having 19 pairs of wheat chromosomes and triply monosomic for either barley chromosome arm 6HL or 3HL, a related wheat chromosome, and chromosome 5B of wheat carrying the phlb mutation. Wheat-barley recombinant chromosomes were isolated from among the progeny obtained from self-fertilization of the triple monosomic stocks, by screening for dissociation of biochemical markers on the barley arms. Glutamic oxaloacetic transaminase (GOT), aconitase hydratase (ACO), and dipeptidase (DIP) isozymes were used to select recombinants involving the 6HL arm, and esterase (EST) and malate dehydrogenase (MDH) were used for the 3HL arm. Altogether, six recombinants involving 6HL (1.4%) and six involving 3HL (1.1%) were isolated. These wheat-barley recombinant chromosomes are being used to construct a detailed gene order map of barley based on biochemical and molecular markers.     

Identification of wheat-Agropyron cristatum monosomic addition lines by RFLP analysis using a set of assigned wheat DNA probes

A non-radioactive digoxigenin-labelled DNA method was used successfully to identify RFLP markers in 54 Triticum aestivum cv Chinese Spring — Agropyron cristatum (2n=28, genome PPPP) P-genome monosomic addition lines. Southern analysis using a set of 14 DNA probes identifying each homoeologous chromosome arm, combined with two restriction enzymes HindIII and EcoRI, indicated that six A. cristatum chromosomes (1P, 2P, 3P, 4P, 5P and 6P) and five A. cristatum chromosome arms (2PS, 2PL, 5PL, 6PS and 6PL) have been individually added to the wheat genome. The added chromosomes of three lines were Agropyron translocated chromosomes. It was also found that two addition plants possessed an Agropyron-wheat translocation. These results showed that RFLP analysis using the set of assigned wheat probes was a powerful tool in detecting and establishing homoeology of alien A. cristatum chromosomes, or arms, added to wheat, as well as in screening the alien addition material. The creation of the monosomic addition lines should be useful for the transfer of disease-resistance genes from A. cristatum to wheat.     

The <Emphasis Type="Italic">Agropyron cristatum</Emphasis> karyotype,chromosome structure and cross-genome homoeology as revealed by fluorescence in situ hybridization with tandem repeats and wheat single-gene probes

Key message

Fluorescence in situ hybridization with probes for 45 cDNAs and five tandem repeats revealed homoeologous relationships of Agropyron cristatum with wheat. The results will contribute to alien gene introgression in wheat improvement.

Abstract

Crested wheatgrass (Agropyron cristatum L. Gaertn.) is a wild relative of wheat and a promising source of novel genes for wheat improvement. To date, identification of A. cristatum chromosomes has not been possible, and its molecular karyotype has not been available. Furthermore, homoeologous relationship between the genomes of A. cristatum and wheat has not been determined. To develop chromosome-specific landmarks, A. cristatum genomic DNA was sequenced, and new tandem repeats were discovered. Their distribution on mitotic chromosomes was studied by fluorescence in situ hybridization (FISH), which revealed specific patterns for five repeats in addition to 5S and 45S ribosomal DNA and rye subtelomeric repeats pSc119.2 and pSc200. FISH with one tandem repeat together with 45S rDNA enabled identification of all A. cristatum chromosomes. To analyze the structure and cross-species homoeology of A. cristatum chromosomes with wheat, probes for 45 mapped wheat cDNAs covering all seven chromosome groups were localized by FISH. Thirty-four cDNAs hybridized to homoeologous chromosomes of A. cristatum, nine hybridized to homoeologous and non-homoeologous chromosomes, and two hybridized to unique positions on non-homoeologous chromosomes. FISH using single-gene probes revealed that the wheat-A. cristatum collinearity was distorted, and important structural rearrangements were observed for chromosomes 2P, 4P, 5P, 6P and 7P. Chromosomal inversions were found for pericentric region of 4P and whole chromosome arm 6PL. Furthermore, reciprocal translocations between 2PS and 4PL were detected. These results provide new insights into the genome evolution within Triticeae and will facilitate the use of crested wheatgrass in alien gene introgression into wheat.

     

A major barley allergen associated with baker's asthma disease is a glycosylated monomeric inhibitor of insect α-amylase: cDNA cloning and chromosomal location of the gene

A 14.5 kDa barley endosperm protein that is a major allergen in baker's asthma disease, as previously shown by both in vitro (IgE binding) and in vivo tests, has been identified as a glycosylated monomeric member of the multigene family of inhibitors of -amylase/trypsin from cereals. A cDNA encoding this allergen (renamed BMAI-1) has been isolated and characterized. The deduced sequence for the mature protein, which is 132 residues long, is identical in its N-terminal end to the 20 amino acid partial sequence previously determined from the purified allergen, and fully confirms that it is a member of the multigene family of cereal inhibitors. Southern-blot analysis of wheat/barley addition lines using the insert in the BMAI-1 cDNA clone as a probe, has led to the location of the allergen gene (Iam1) in barley chromosome 2, while another related member of this protein family, the barley dimeric -amylase inhibitor BDAI-1 gene (Iad1) has been located in chromosome 6. Iam1 is the first member of this inhibitor family in cereals to be assigned to chromosome group 2, thus extending the dispersion of genes in the family to five out of the seven homology groups of chromosomes in wheat and barley (chromosome 2, 3, 4, 6 and 7).     

Biochemical evidence of homoeology between Triticum aestivum and Agropyron intermedium chromosomes

Summary The alcohol dehydrogenase (ADH), phosphoglucose mutase (PGM), glucosephosphate isomerase (GPI), glutamic oxaloacetic transaminase (GOT), malate dehydrogenase (MDH), leaf esterases (ESTL), leaf acid (ACPH) and endosperm alkaline (PHE) phosphatases, leaf peroxidases (PERL) zymogram phenotypes of Triticum aestivum, Agropyron intermedium, Triticum aestivum — Agropyron intermedium octoploids and six Agropyron intermedium chromosome additions to Triticum aestivum and two ditelocentric addition lines were determined. It was found that the six disomic chromosome addition lines and one ditelocentric chromosome addition line could be distinguished from one another and from the other possible lines on the basis of the zymogram phenotypes of these isozymes. The structural gene Acph-X1 was located on Agropyron chromosome L1, the genes Got-X3 and Mdh-X2 on chromosome L2, the gene Gpi-X1 on chromosome L3, the genes Adh-X1, Pgm-X1 and Phe-3 on chromosome L4, gene Perl-1 on chromosome L5 and the gene Estl-2 on chromosome L7 and chromosome arm L7d2. These gene locations provide evidence of homoeology between Agropyron chromosomes L1, L2, L3, L4, L5 and L7 and the Triticum aestivum chromosomes of homoeologous groups 7, 3, 1, 4, 2 and 6, respectively.     

The genetical control and tissue-specificity of esterase isozymes in hexaploid wheat

A comparative genetic analysis of esterase (E.C.3.1.1.1) isozymes of wheat cultivar Chinese Spring in endosperm, embryo, coleoptile, leaf and root tissues revealed eight sets of isozymes characterised by different tissue specificities, pI ranges and the chromosomal locations of their controlling genes. This data was considered together with previously published work, resulting in a proposed rationalization of nine sets of wheat esterase isozymes. Although this classification included two sets of isozymes controlled by genes on the short arms of homoeologous group 3 chromosomes and three sets on the long arms of the same chromosomes, for which no recombination evidence of genetic distinctness has been obtained among either group, it is argued that the different characteristics of the various sets warrant retention of separate set nomenclatures. Previously unreported esterase genes includeEst-9, a low pI, monomeric, embryo-specific group with controlling genes on chromosomes 3BS and 3DS and two further members ofEs-1,Est-H1 inHordeum vulgare andEst-S ^l1 inAegilops longissima.