The chromosomal location of factors determining the presence of phenolic compounds in wheat (Triticum aestivum L.)

Summary Using thin-layer chromatography and nulli-tetrasomic and ditellosomic series of Triticum aestivum L. cv. Chinese Spring, it has been possible to relate the phenolic compounds found in adult plant leaves and 12 day-old seedling leaves with the chromosomes or chromosome arms 1 B, 2 BL, 3 BL, 5 A, 6 AL, 7 B and 7 DS.     

Aneuploid and alloplasmic lines as tools for the study of nuclear and cytoplasmic control of culture ability and regeneration of scutellar calli from common wheat

Summary Twenty four B genome aneuploid lines (di-telosomics, nullisomic-tetrasomics and tetrasomics) of Triticum aestivum cv Chinese Spring were used in an analysis of the culture ability and regeneration capability of scutellar calli. Several correlations were found between the presence or absence of specific chromosomes and chromosomal arms of the B genome of common wheat and the growth and differentiation capabilities of these calli. The rate of callus growth decreased only when the long arm of chromosome 6B was not present. The absence of chromosomes 3B and 7B did not result in an apparent change in morphogenetic capability, while the absence of other B genome chromosomes was significantly correlated to changes in the frequency of calli that regenerated plants. The presence of the short arm of chromosome 1B was negatively correlated with regeneration, whereas its long arm is probably required to counteract this effect and to maintain the normal ratio of regeneration. The presence of the chromosomal arm 2BS seemed to be essential for differentiation to shoots. In the absence of the short arms of chromosomes 4B and 5B, the rate of regeneration was slightly reduced. In the absence of the long arm of chromosome 6B there was a marked reduction of the ability of scutellar calli to regenerate plants. The use of additional aneuploid lines belonging to homoeologous group 6 revealed that only calli derived from lines having chromosome 6D in their complement regenerated plants similarly to the euploid control. Culture ability and regeneration capability were also analysed with alloplasmic lines of T. aestivum cv Chris. The lines were derived from five species, representing plasma-types of different phylogenetic distances from plasma-type B of T. aestivum. The results showed that when the endogenous cytoplasm (B-type) was exchanged with T. timopheevii cytoplasm (G-type) there was a significant increase in the regeneration of shoots from the scutellar calli.     

Use of recombinant substitution lines in the construction of RFLP-based genetic maps of chromosomes 6A and 6B of tetraploid wheat (Triticum turgidum L.)

RFLP-based genetic maps of chromosomes 6A and 6B of Triticum turgidum have been constructed using data obtained by the study of Triticum turgidum var durum cv Langdon-T. t. var dicoccoides recombinant substitution lines (RSLs) supplemented with data obtained from F₃ families derived from Langdon dicoccoides 6A and 6B disomic substitution lines. The average RFLP frequencies detected for the two chromosomes in a test of 45 DNA clones with six restriction enzymes were 56% and 53%, respectively, and a subset of 32 clones gave frequencies of 75% and 72%, respectively. Seventeen loci were mapped in 6A and 18 in 6B. With the possible exception of 5 loci in the centromeric region of 6A, all of the mapped 6A and 6B loci are located in the same arm as are homologous loci in hexaploid wheat, and the linear order of the loci is the same in the two chromosomes, except possibly close to the centromere. Major differences in genetic distances exist between homologous loci located in the proximal regions of the 6AL and 6BL linkage groups, however, the distances being much larger in the former than in the latter. The 6B maps that were constructed using data from both the RSL and the F₂ populations and using data from the RSL population alone closely resemble one another, indicating that the 6B RSL population, composed of 85 lines, can be reliably used for genetic mapping. Additional studies must be conducted before the utility of the 6A RSL population, composed of 66 lines, can be adequately assessed.     

Fractionation of wheat gliadin and glutenin subunits by two-dimensional electrophoresis and the role of group 6 and group 2 chromosomes in gliadin synthesis

Summary Subunits of wheat endosperm proteins have been fractionated by two-dimensional electrophoresis. To determine which subunits in the two-dimensional electrophoretic pattern belong to gliadin or glutenin the endosperm proteins have also been fractionated by a modified Osborne procedure and by gel filtration on Sephadex G-100 and Sepharose CL-4B prior to separation by two-dimensional electrophoresis.The control of production of five major grain protein subunits is shown to be determined by chromosomes 6A, 6B and 6D by comparing two-dimensional electrophoretic protein subunit patterns of aneuploid lines of the variety Chinese Spring. From these and previous studies it is concluded that some , and gliadins (molecular weights by SDS-PAGE 30,000 to 40,000) are specified by genes on the short arms of homoeologous Group 6 chromosomes, the gliadins (molecular weights by SDS-PAGE 50,000 to 70,000) are specified by genes on the short arms of homoeologous Group 1 chromosomes and the glutenin subunits (molecular weights by SDS-PAGE > 85,000) are specified by genes on the long arms of homoeologous Group 1 chromosomes.No major gliadins or glutenin subunits were absent when any of the chromosomes in homoeologous Groups 2, 3, 4, 5 or 7 were deleted. However two gliadins whose presumed structural genes are on chromosome 6D were absent in aneuploid stocks of Chinese Spring carrying two additional doses of chromosome 2A. Two out of thirty-three intervarietal or interspecific chromosome substitution lines examined, involving homoeologous Group 2 chromosomes, lacked the same two gliadins. All the subunits in the other thirty-one chromosome substitution lines were indistinguishable from those in Chinese Spring. It is therefore concluded that the major variation affecting gliadin and glutenins in wheat is concentrated on the chromosomes of homoeologous Groups 1 and 6 but Group 2 chromosomes are candidates for further study.An endosperm protein controlled by chromosome 4D in Chinese Spring is shown to be a high molecular weight globulin.     

Cytogenetic analysis of structural rearrangements in three varieties of common wheat,Triticum aestivum

Summary The winter wheat varieties Starke and Cappelle Desprez and the spring wheat Chinese Spring were analysed for structural chromosome rearrangements that resulted in the formation of multivalents in F₁ hybrids. The analyses were carried out using hybrids involving euploids, monosomic and ditelosomic stocks, and double-monotelodisomic constructs. The study confirmed that Cappelle Desprez differs from Chinese Spring in a reciprocal translocation between chromosomes 5B and 7B (Riley et al. 1967); a translocation involving chromosomes 3B and 3D could not be verified. Furthermore, the analysis showed that Starke differs from Chinese Spring in a reciprocal translocation between chromosomes 7A and 7D. Both translocations have a coefficient of multivalent realisation of about 0.84. Further multivalents in euploid Starke, in euploid and some aneuploid stocks of Cappelle Desprez, and in euploid as well as various types of aneuploid hybrids between all three varieties could nearly all be explained hypothesizing that chromosome 2B of both Starke and Cappelle Desprez is a duplication-deficiency chromosome. In the hypothesis a part of the long arm of 2B is missing and replaced by a duplicated part of the long arm of chromosome 2D. The multivalents of this rearrangement showed an average coefficient of realisation of about 0.09.Sven Ellerström died in December 1985     

Comparative study ofTriticum aestivum andT. timopheevi genomes using C-banding technique

The somatic chromosomes ofTriticum timopheevi and those of two varieties ofT. aestivum, Chinese Spring and Bezostaya-1, have been identified by a Giemsa staining technique. The data suggest thatT. timopheevi and tetraploid wheats had a common ancestor from which their genomes differentiated due to chromosomal aberrations and the increase of heterochromatin in the chromosomes of theT. timopheevi G-genome. The differences between the chromosomes of the AB and AG genomes result in substitutions and large translocations between these chromosomes in interspecific hybrids.     

Control of lectins in Triticum aestivum and Aegilops umbellulata by homoeologous group 1 chromosomes

Summary Each of the three genomes in hexaploid wheat controls the expression of a specific lectin in the embryo. The chromosomes which control their synthesis were determined using nullisomic-tetrasomic and inter-varietal chromosome substitution lines of Chinese Spring. All three wheat lectins were shown to be controlled by the homoeologous group 1 chromosomes. Using ditelosomic lines of Chinese Spring the lectin genes could be localized on the long arms of chromosomes 1A and 1D. Inter-specific addition and substitution lines of Aegilops umbellulata chromosomes to Chinese Spring indicated that chromosome 1U, which is homoeologous to the group 1 chromosomes of wheat, controls lectin synthesis.     

Meiotic pairing and alpha-amylase phenotype in a 5B/5Rm Triticum aestivum — Secale montanum translocation line in common wheat

Summary A 5BS/5R^mS translocation chromosome spontaneously recovered from a Chinese Spring — Secale montanum wheat-rye telocentric 5R^mS addition line has been identified and cytologically studied using C-banding in somatic and meiotic cells. Analysis of the translocated chromosome showed that a terminal segment of the short arm of 5B had been replaced by a short terminal region of chromosome arm 5R^mS. The translocation led to the deletion of the genetic system promoting pairing located in 5BS, which is slightly compensated for when doses of 5R^mS are increased, indicating homoeology to wheat chromosome 5BS. The -amylase phenotype in 5B/5R^m translocated material was studied and found to be identical to that of ditelocentric line 5BL of Chinese Spring. An effect on the -amylase activity was detected as a result of the removal of the terminal region of 5BS, perhaps as a consequence of variation in dormancy period duration.     

High crossability of wild barley (Hordeum spontaneum C. Koch) with bread wheat and the differential elimination of barley chromosomes in the hybrids

Four bread wheat (Triticum aestivum L.) cultivars, Aobakomugi, Chinese Spring, Norin 61 and Shinchunaga, were pollinated with five barley lines/cultivars consisting of three cultivated barley (Hordeum vulgare L.) lines, Betzes, Kinai 5 and OHL089, and two wild barley (Hordeum spontaneum C. Koch) lines, OUH602 and OUH324. Crossability, expressed as the percentage of embryo formation, varied from 0 to 55.4% among the cross combinations. The two wild barley lines generally had a higher crossability than the previously reported best pollinator, Betzes, and some Japanese wheat cultivars were better as the female parent than Chinese Spring. Ninety four hybrid plants were obtained from 250 embryos cultured, and their somatic chromosome numbers ranged from 21 to 36. Eighteen plants were mosaic in chromosome number. Twenty one-chromosome plants appeared most frequently (45.7%) followed by 28-chromosome plants (14.9%). C-banding analysis revealed that elimination of barley chromosomes was mainly responsible for the occurrence of aneuploid plants. In hypoploids derived from Betzes-crosses, chromosome 5 was preferentially eliminated as previously reported, while in hypoploids derived from OUH602-crosses, chromosome 4 was preferentially eliminated. The wild barley line OUH602 may be a useful parent for producing a new wheat-barley addition set because of its high crossability with wheat and a different pattern of chromosome elimination.     

The meiotic pairing of nine wheat chromosomes

Summary The meiotic identification of nine pairs of chromosomes at metaphase I of meiosis of Triticum aestivum (B genome, 4A and 7A) has been achieved using a Giemsa C-banding technique. As a result, the analysis of the pairing of each chromosome arm in disomic and monosomic intervarietal hybrids between Chinese Spring and the Spanish cultivar Pané 247 could be carried out. Differences in the chiasmata frequencies per chromosome arm cannot be explained on the basis of relative arm lengths only. Possible effects of arm-to-arm heterochromatic differences on meiotic pairing are discussed.     

Chromosome structure of Triticum longissimum relative to wheat

Homoeologous pairing at meiotic metaphase I was analyzed in T. longissimum x T. aestivum hybrids in order to reconfirm the homoeologous relationships of T. longissimum chromosomes to wheat. Hybrids between T. longissimum and Chinese Spring carrying the Ph1 gene or theph1b mutation, which showed low and high pairing levels, respectively, were used. Chromosome arms associated at metaphase I were identified by C-banding. The homoeology of chromosomes 1S ^l , 2S ^l , 3S ^l , 5S ^l and 6S ^l to wheat group 1,2, 3, 5, and 6 chromosomes, respectively, was confirmed. Chromsome arms 4S ^l S and 7S ^l S showed normal homoeologous relationships to wheat. The 4S ^l L arm carries a translocated segment from 7S ^l L relative to wheat. The 7S ^l L arm seldom paired, likely because this arm lost a relatively long segment and received a very short segment in the interchange with 4S ^l L. Available data suggest that translocation 4S ^l L/7S ^l L arose in the evolution of T. longissimum, which implies that this species was not the donor of the B genome of wheat.     

Dosage effects of chromosomes of homoeologous groups 1 and 6 upon bread-making quality in hexaploid wheat

Summary The endosperm storage proteins, glutenin and gliadin, are major determinants of bread-making quality in hexaploid wheat. Genes encoding them are located on chromosomes of homoeologous groups 1 and 6. Aneuploid lines of these groups in spring wheat cultivar Chinese Spring have been used to investigate the effect of varying the dosage of chromosomes and chromosome arms upon bread-making quality, where quality has been assessed using the SDS-sedimentation test. Differences between the group 1 chromosomes for quality were greater than those between the group 6 chromosomes. The chromosomes were ranked within homoeologous groups for their effect on quality as follows (>=better quality): 1D>1B>1A and 6A>6B=6D. The relationship of chromosome dosage with quality was principally linear for four of the chromosomes, but not for 6B and 6D. Increases in the dosage of 1B, 6A and, especially, 1D, were associated with significant improvements in quality, whereas increases in the dosage of 1A were associated with reductions in quality. The effects of 1A and 1D were such that the best genotype for quality was nullisomic 1A-tetrasomic 1D. For group 1, effects of the long arm appeared in general to be more important than effects of the short arm. For group 6, effects were found associated with the long arms as well as with the short arms, a surprising result in view of the absence of genes encoding storage proteins on the long arms. Significant interactions were found between chromosomes and genetic backgrounds, and between individual chromosomes. Analysis of trials grown over two years demonstrated that, although additive environmental differences over years and genotype x years interaction were present, they were relatively small in magnitude compared with purely genetic differences.     

The modification of a common wheat-Thinopyrum distichum translocated chromosome with a locus homoeoallelic to Lr19

Summary The Chinese Spring ph1b and ph2b mutants, as well as the nulli 5B tetra 5D stock were utilized in an attempt to effect homoeologous chromatin exchange between the Indis chromosome translocation [derived from Thinopyrum distichum (Thunb.) Löve] and chromosome arm 7DL of common wheat. A homoeoallele of Lr19 and linked genes for yellow flour-pigmentation were utilized as markers. Seven selections with recombinations involving the foreign, translocated segment were recovered. Four of these had white endosperms and were leaf-rust resistant. The remaining lines were leaf-rust resistant and had levels of endosperm pigmentation intermediate to those of Indis and Chinese Spring. The recombined translocation segments coding for white endosperm are no longer associated with chromosome 7D. The original translocated segment may, therefore, not be fully homoeologous to 7DL. The recombinants with white endosperm also lack the stem-rust resitance gene Sr25, but retained the segregation distorter locus, Sd-1. However, it seems as though an enhancer locus (or loci) of Sd-1 had been lost.     

Genetics of yellow berry in wheat (Triticum aestivum)

Summary The inheritance of yellow berry, a grain disorder in durum and bread wheats, was studied in six intervarietal crosses in bread wheat. The trait was found to be controlled by either two or three dominant genes. Monosomic analysis using Chinese Spring monosomic series showed the presence of two major dominant genes on chromosomes 1A and 7A, and four modifiers on 4A, 4B, 6A and 6D, which influence the expression of yellow berry in bread wheat.     

Two-step one-dimensional SDS-PAGE analysis of LMW subunits of glutelin

Summary Analysis of intergeneric substitution lines in hexaploid wheats by a two-step electrophoretic method of protein separation revealed that low-molecular-weight (LMW) subunits of glutelin in Triticum longissimum, T. Umbelullatum, Elytrigia elongata (2 x) were controlled by chromosomes/chromosome arms 1S ^l , 1U, and 1ES, respectively. A LMW glutelin band in Secale montanum was detected but its chromosomal location could not be determined. Genes controlling gliadins and HMW subunits of glutelin were also located on chromosome 1S ^l in T. longissimum.The term glutelin refers to the polymeric prolamins of cereals, e.g., glutenins in wheat, HMW, and 75-k secalins in rye     

The addition of Dasypyrum villosum (L.) Candargy chromosomes to durum wheat (Triticum durum Desf.)

Summary Six monosomic addition lines were produced in which different Dasypyrum villosum (L.) Candargy chromosomes were added to the chromosome complement of Triticum durum Desf. cv. Creso. Each added alien chromosome was found to have a specific effect on plant morphology and fertility. Transmission rate varied widely (from 7.5 to 27.7%) among the six univalent chromosomes. Different monotelosomic addition plants derived by a relatively high frequency of chromosome misdivision were isolated. The addition lines should be useful for studying Dasypyrum chromosome homoeology and the introduction of alien variation into durum and common wheats.Research supported by a grant from the Italian Research Council for Finalized Project IPRA. Sub-project Plant Breeding, Paper No. 1095     

Investigation of a preferentially transmitted Aegilops sharonensis chromosome in wheat

Summary An attempt to produce a set of addition lines of Aegilops sharonensis to the wheat variety Chinese Spring produced only one addition line. This was due to preferential transmission of one chromosome from Ae. sharonensis. This chromosome was studied in detail by established cytological methods of chromosome observation and by the newer techniques of C-banding and in situ hybridization of a cloned DNA sequence. The chromosome was found to be partially homologous to an Ae. sharonensis chromosome of similar behaviour in another wheat addition line. The incomplete homology of the two Ae. sharonensis chromosomes was due to the presence of a translocated segment of a wheat chromosome. — Substitution lines of the Ae. sharonensis chromosome for wheat homoeologous group 4 were produced and the Ae. sharonensis chromosome thereby designated 4 S ^l .     

Dosage effects of the three Wx genes on amylose synthesis in wheat endosperm

Amylose synthesis in wheat endosperm is mainly controlled by the granule-bound starch synthase of about 60 kDa, the so-called waxy (Wx) protein. The Wx proteins are the product of the Wx genes at a triplicate set of single-copy homoeoloci located on chromosomes 7A (Wx-A1), 4A (Wx-B1) and 7D (Wx-D1). Using Chinese Spring and its aneuploid lines, including nullisomic-tetrasomics, tetrasomics, ditelosomics and deletion stocks, together with single-chromosome substitution lines for these chromosomes, the effects of varying the dosage of whole chromosomes and chromosome arms, as well as the effects of null alleles, upon amylose synthesis were investigated. Nullisomic 4A and the deletion of chromosome segments carrying the Wx-B1 gene reduced the amylose content by more than 3%. A reasonable agreement was found in the substitution lines. This confirms that the absence of the Wx-B1 gene, or else substitution of this gene by its null allele, has the most striking effect on decreasing amylose synthesis. The removal of chromosomes carrying either the Wx-A1 or the Wx-D1 gene reduces the amylose content by less than 2%. A similar reduction was revealed by substitution of these two genes by the null alleles. Double dosages of chromosomes 7A, 4A and 7D did not increase amylose content, while the tetrasomic chromosomes produced more of the respective Wx proteins. This suggests that a certain level of Wx gene activity or of the Wx proteins led to the maximum amount of amylose.     

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.     

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.