The synthesis and deposition of the prolamin storage proteins (secalins) of rye

The synthesis and deposition of the endosperm storage proteins of rye, usually termed secalins, has been studied. The rate of accumulation of secalin in developing rye grain was at a maximum between 3 and 5 weeks after anthesis. Some changes in the proportions of the four major groups of secalin polypeptides were observed during maturation, notably an increase in γ-secalins of M_r 75k and a decrease in ω-secalins. In-vitro translation of mRNA fractions prepared from 4-week-old endosperms showed that secalin polypeptides were synthesised on membrane-bound polysomes. The secalin products were identified by their mobilities on SDS-PAGE and their relative incorporation of radioactive lysine, glycine, proline, leucine and methionine. Protein bodies prepared by sucrose density ultracentrifugation contained reduced amounts of γ-secalins of M_r 40k and ω-secalins compared with the total secalin fraction, but these components were present in the expected amounts when 1.0 M NaCl was added to the buffers. Treatment of the protein bodies with proteinase-k resulted in the digestion of their contents regardless of the presence of NaCl, indicating that the surrounding membrane was incomplete. It was concluded that the NaCl reduced the loss of secalins from the protein bodies by decreasing secalin solubility rather than by affecting the integrity of the protein body membrane. The results reported for the synthesis and deposition of secalins are consistent with the results of previous studies on the prolamins of wheat and barley.     

The chromosomal locations of leaf peroxidase genes in hexaploid wheat,rye and barley

Summary Eight leaf peroxidase isozymes were distinguished by IEF in Chinese Spring. Two genes which control the production of three of these isozymes were located on chromosome arms 1BS and 1DS by nullisomic analysis. These loci probably form part of a homoeoallelic series and have been designated Per-B1 and Per-D1 respectively. Analysis of chromosome 1B short arm terminal deletion stocks indicated that the Per-B1 locus is located between the nucleolar organiser region and another isozyme marker, Hk-B1. Two variant leaf peroxidase phenotypes were distinguished in a small sample of hexaploid wheat varieties. Analysis of wheat-alien addition and substitution lines identified homoeologous loci in rye (Per-R1) and barley (Per-H1).     

Mapping seed storage protein loci Sec-1 and Sec-3 in relation to five chromosomal rearrangements in rye (Secale cereale L.)

Summary Linkage relationships were established between the secalin loci, Sec 1 (40-K gamma and omega secalins, homologous to the wheat gliadins) and Sec 3 (HMW = high-molecular-weight secalins, homologous to the wheat HMW glutenin subunits), and five chromosomal rearrangements involving chromosome 1R of rye (Secale cereale L.). These were: interchanges T273W (1RL/5RS), T306W (1RS/5RL), and T850W (1RS/ 4RL), Robertsonian centromere split Rb1RW and the interchanged Robertsonian split Rb2R/248W. The analysis established the linkage relationships between the secalin loci and the breakpoints of the rearrangements, in addition to the quantitative effects of the rearrangements on the linkage. Sec-1 is located in the satellite at a position at least 2.5 cMorgan from the proximal border of the terminal C-band, and about 30 cMorgan from the nucleolar organizing region (NOR). The locus is also physically closer to the terminal C-band than to the NOR, but not as much as corresponds with the map distances. Similarly, the physical distance between Sec-3 and the centromere is greater than corresponds with the recombination frequency (0%–9%). Although overall recombination in 1RL remains the same, recombination between the centromere and Sec-3 is greatly reduced in the Robertsonian split combined with the interchange. This is not the case with the single Robertsonian split.     

Absence of qualitative genes controlling interspecific pairing in rye B chromosomes

Summary The meiotic behaviour of hybrids between Secale cereale carrying B chromosomes and S. vavilovii has been studied in order to estimate the effects of B chromosomes on hybrid meiotic pairing. The possible effect of Bs on the meiotic pairing of the offspring from backcrosses with S. vavilovii has been studied also. The results obtained clearly indicate that no detectable differences existed in chromosome pairing of hybrids with or without B chromosomes. The hypothetical existence of epistatic genes on cereale genome masking the effect of Bs has been rejected after the results obtained in backcrosses. Therefore, lack of qualitative genes controlling interspecific pairing on rye B chromosomes has been concluded. A quantitative effect of B chromosomes was detected only when they were in alien cytoplasm.     

Analysis of the effect of rye chromosomes 4R, 6R and telomeric heterochromatin on 7R on homologous chromosome pairing in pentaploid hybrids (AABBR,AABBD)

Summary Meiotic pairing in Triticum turgidum cv. Ma (4x) with a mean chiasmata frequency of 27.16 per cell was compared with chiasmata frequencies in its hybrids with several triticale strains, Chinese Spring wheat and its addition lines for Imperial rye chromosomes 4R and 6R. In hybrids between Ma and x Triticosecale cv. Rosner the chiasmata frequency was marginally reduced by an average of 1.25%, by 8.8% in hybrids with x Triticosecale cv. DRIRA HH and by 6.7% with DRIRA EE (lacking 90% telomeric heterochromatin from chromosome arm 7RL). In pentaploid hybrids between Ma and T. aestivum cv. Chinese Spring the reduction was an average of 10.30%, while addition lines with rye chromosome 6R reduced chiasmata frequencies by an average of 7.4% and rye addition line for 4R showed the greatest depression in chiasmata frequency in hybrids by a 25.04% reduction. An interchange difference involving long chromosome segments was observed between Ma and Rosner.Contribution No. 819 Ottawa Research Station     

The chromosomal locations of enzyme-coding genes Adh-1 and Pgm-1 in Allium fistulosum L.

Summary The chromosomal locations of two enzymecoding genes were investigated using allele dosage effects in two Allium cepa alien addition lines possessing different A. fistulosum chromosomes as the trisomes. Adh-1 has been assigned to the A. fistulosum sub-telocentric chromosome 5, while Pgm-1 is on the A. fistulosum submetacentric chromosome 4. Karyotype data of a shortday cultivar of A. cepa, Temprana, A. fistulosum Ishikura Long White, and the relevant chromosomes of the two trisomies are presented.Contribution of the College of Agricultural Sciences, Texas Tech University, Journal No. T-4-224     

The inheritance of rye seed peroxidases

Summary Genetic analyses were conducted on peroxidase of the embryo and endosperm of seeds of one open pollinated and six inbred lines of cultivated rye (Secale cereale L.), and one line of Secale vavilovii Grossh. The analyses of the individual parts of the S. cereale seed yield a total of 14 peroxidase isozymes. Isozymes m, a, b, c, d, e, f and g (in order from faster to slower migration) were found in the embryo plus scutellum, while isozymes 1, 2, 3, 4, 5 and 6 (also from faster to slower migration) were peculiar of the endosperm. S. vavilovii has isozymes m, c₁, d, e, f and g in its embryo plus scutellum, and isozyme 2 in the endosperm. Segregation data indicated that at least 13 different loci would be controlling the peroxidase of S. cereale. Isozymes a and b are controlled by alleles of the same locus, all the other loci have one active and dominant allele coding for one isozyme, and other null and recessive allele. The estimation of linkage relationships shows that five endosperm loci are linked, and tentative maps are shown. A possible dosage effect and the existence of controlling gene(s) for endosperm isozyme 4 is reported. All these data and the high frequency of null alleles found are discussed in relation to recent reports.     

Heterochromatin and silver banding of rye (Secale cereale,Gramineae) chromosomes

Air-dried chromosomes of rye when stained with aqueous silver nitrate show differential banding patterns. In addition to staining the NOR sites, the silver nitrate stains all regions of constitutive heterochromatin, as identified by Giemsa C-banding, as well as a number of small interstitial regions. However, the heterochromatin on the B chromosome is not stained by the silver method. This is proposed as a rapid and reliable banding method.     

Homoeologous chromosomal location of the genes encoding thionins in wheat and rye

Summary Thionins are high sulphur basic polypeptides present in the endosperm of Gramineae. In wheat there are three thionins encoded by genes located in the long arms of chromosomes 1A, 1B and 1D. Rye has one thionin encoded by a gene which has been assigned to chromosome 1R after analysis of the Imperial-Chinese Spring rye-wheat disomic addition lines. Commercial varieties and experimental stocks with a 1B/1R substitution carry the thionin from rye ( _R) instead of the _B thionin from wheat. The _R thionin gene is not located in the large chromosomal segment representing most of the short arm of chromosome 1R.     

Linkage and cytogenetic maps of genes controlling endosperm storage proteins and isozymes in rye (Secale cereale L.)

Summary An F₁ plant fromSecale cereale ssp.ancestrale xtelocentric substitution lines3R of the cultivated rye Petkus spring was used as female in a cross with the inbred line Riodeva (I28), which has the standard chromosome arrangement. Single plants from this backcross progeny were analyzed for chromosome constitution, storage protein, and isozymic patterns. The seed protein loci were identified asSec-1a andSec-1b loci controlling 40-K-secalins and-secalins, respectively. These loci are located on the short arm of chromosome1R. TheSec-3 locus controlling high-molecular-weight secalins is located on the long arm of chromosome1R. A further seed protein locus,Pr-3 (55-K protein), was located on the short arm of chromosome1R. A linkage was found between the6Pgd-2 isozyme locus controlling 6-phosphogluconate dehydrogenase isozymes located on the long arm of chromosome1R and the four seed protein loci. The results favor the gene order:6Pgd-2 ...Sec-3 ... [centromere] ...Pr-3 ...Sec-1b ...Sec-1a. Other linkages detected werePer-3a andPer-3b (0.33±0.33 cM),Est-8 andEst-12 (0.33±0.33 cM), andGot-3 and centromere (20.57±2.42 cM). The proxidase (Per), glutamate oxaloacetate transaminase (Got), and esterase (Est) loci were located on chromosome arms2RS,3RL, and6RL, respectively. The distances and the maps obtained are compared with data available in the literature.     

Intrachromosomal mapping of crossability genes in wheat (Triticum aestivum)

Summary Intrachromosomal mapping studies were used to locate the positions of the genes Kr1 and Kr2, which control the crossability of wheat with Hordeum bulbosum, on chromosomes 5B and 5A, respectively. The location of Kr1 was established using the telocentric mapping technique and found to be on the long arm of chromosome 5B, distal to the centromere with a mean recombination frequency of 44.8±3.28%. Kr2 was located on the long arm of chromosome 5A by linkage with the major gene markers Vrn1, controlling vernalization requirement, and q, controlling ear morphology. Kr2 is closely linked to Vrn1, with a mean recombination frequency of 4.8±4.66%, and is distal to q with a mean recombination frequency of 38.1±10.60%. The similar locations of Kr1 and Kr2 on homoeologous chromosomes suggest that these two loci are homoeoallelic. Significant correlations between Hordeum bulbosum and rye crossability confirmed that Kr1 and Kr2 control the crossability of wheat with both species.     

Molecular analysis of mitochondrial DNA from rye (Secale cereale L.)

Summary Molecular characterization of mitochondrial (mt) DNA of rye (Secale cereale L.), free of significant amounts of contaminating chloroplast (cp) DNA, was initiated using the open-pollinated cultivar Halo as a source of mtDNA. Based on the compilation of data from restriction patterns, the molecular size of the mtDNA was estimated to be 410 Kb and its buoyant density was determined as 1.705 g/ml. Southern hybridization, using labelled cp genes (P700 and ribulosebiphosphate-carboxylase large subunit), indicated the presence of cpDNA-homologous regions on putative mtDNA fragments. Mt DNAs of inbred lines with fertile and cytoplasmic male sterile (CMS) Pampa cytoplasm were also analysed. Whereas the restriction patterns of mtDNAs of Halors and the fertile line turned out to be identical, Pampa mtDNA showed a unique restriction pattern, indicating (as in most other CMS systems) the involvement of mtDNA rearrangements in the expression of male sterility in rye. All 3 mtDNAs investigated contain regions homologous to the plasmid S1 of the CMS-S cytoplasm of Maize (Zea mays), as indicated by hybridization experiments. In Pampa cytoplasm the S-homologous sequence is located within a rearranged region of mtDNA.     

RFLP mapping of the dwarfing (Ddw1) and hairy peduncle (Hp) genes on chromosome 5 of rye (Secale cereale L.)

An F₂ population was established for mapping the two dominant genes for dwarfness (Ddw1) and hairy peduncle (Hp) on chromosome 5R. The location of both genes was shown to be on the segment of chromosome 5RL which was ancestrally translocated and is homoeologous to Triticeae 4L. Hp cosegregated with the wheat gDNA probe WG199, localised in wheat on chromosomes 5AL, 4BL and 4DL. No segregation was observed between the traits hairy peduncle and hairy leaf sheath. The locus for Ddw1 was found to map distally to Hp/Xwg199 but proximal to the isozyme marker -amy-R1. The genetical distances were 5.6 cM between Hp/Xwg199 and Ddw1 and ll.ScM between Ddw1 and -amy-R1, respectively. The map position of Ddw1 suggests that it is homoeologous to the wheat dominant dwarfing gene Rht12, present on chromosome 5AL and linked to -amy-A1.     

Chromosomal location of the catalase structural genes in Zea mays using B-A translocations

Summary B-A translocations have been used to map the catalase genes, Cat1, Cat2, and Cat3 of Zea mays. Cat1 was found to be on the short arm of chromosome 5, 9.1 map units from brittle endosperm (bt ₁). Cat2 was located on chromosome 1S, while Cat3 was located on the distal half of chromosome 1L. There was no linkage between Cat2 and Cat3. The significance of mapping the catalase structural genes is discussed.This research was supported by Grant No. GM22733 from the National Institute of General Medical Sciences, National Institutes of Health, USPHS to JGS.This is Paper No. 6437 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC     

Linkage relationships between prolamin genes on chromosomes 1A and 1B of durum wheat

Gliadin and glutenin electrophoresis of F₂ progeny from four crosses of durum wheat was used to analyse the linkage relationships between prolamin genes on chromosomes 1A and 1B. The results showed that these genes are located at the homoeoallelic lociGlu-1,Gli-3,Glu-3 andGli-1. The genetic distances between these loci were calculated more precisely than had been done previously for chromosome 1B, and the genetic distances betweenGli-A3,Glu-A3 andGli-A1 on chromosome 1A were also determined. Genes atGli-B3 were found to control some-gliadins and one B-LMW glutenin, indicating that it could be a complex locus.     

Phylogenetic relationships inSecale (Poaceae): An isozymatic study

The genetic frequencies of 9 isozyme loci have been estimated in 23 samples of 4 species ofSecale by means of starch gel electrophoresis. The populations ofS. silvestre andS. vavilovii were monomorphic and uniform within each species, those ofS. montanum andS. cereale were polymorphic for most of the isozyme loci. On the basis of isozyme patterns as well as allelic and genotypic frequencies of isozyme loci,S. silvestre can be distinguished fromS. vavilovii, and both fromS. cereale andS. montanum; but there is no clear differentiation between the two latter species. Clusters constructed from genetic distances separateS. silvestre andS. vavilovii, whereasS. cereale andS. montanum were grouped together. The isozymatic data presented here, along with cytogenetic and life habit data, agree with the generally admitted existence of 4 species inSecale, and support the relationships suggested byKhush & Stebbins (1961).     

Regulation of transcription and promoter mapping of the structural genes for nitrogenase (nifHDK) of Azospirillum brasilense Sp7

A galactose-inducible HO gene was used to induce mating type switching in heterothallic Saccharomyces cerevisiae cells arrested in G1, in rad52 mutants defective in DNA damage repair, and in cells lacking the donor cassettes. The HO-cleaved MAT intermediate is stable over significant lengths of time, i.e. HO cleavage is not coupled to the subsequent gene conversion event. The in vivo cleavage site was mapped to single base resolution by primer extension experiments on total genomic DNA. Cells arrested in G1 with alpha-factor switched mating type thus demonstrating that switches can occur in the absence of replication of the genome. rad52 mutants did not produce MAT DNA of the opposite mating type indicating that the block is prior to the gene duplication stage of the switch. In strains in which the HM donor cassettes are deleted the cut MAT DNA was degraded after induction of the HO gene.     

Genetic studies of self-fertility in rye (Secale cereale L.). 2. The search for isozyme marker genes linked to self-incompatibility loci

The segregation of several isozyme marker genes has been studied in F₂ inbred families from hybrids between self-sterile and five self-fertile inbred lines (nos. 2, 3, 4, 5, and 8) as well as from interline hybrids. Self-pollination of F₁ hybrids between self-sterile forms and lines 5 and 8 gave an F₂ segregation ratio of 1 heterozygote:1 homozygote for the gene Prx7 (chromosome 1R) against the allele from the line. This is interpreted as a result of tight linkage of the Prx7 gene with the S1 gene in chromosome 1R (recombination at a level of 0–1%). The self-pollination of such hybrids with lines 2,3 and 4 gave normal segregation for the Prx7 gene (1:2:1). This means that these lines carry a self-fertility allele which is not on chromosome 1R. Interline hybrids 5×2, 5×3 and 5×4 had self-fertility alleles for the two S genes and in inbred F₂ progenies gave the expected deviating segregation for the Prx7 gene in a ratio of 2:3:1. The segregation of interline hybrid 5×8 was normal, 1:2:1, as expected. Highly-deviating segregation in an inbred F₂ family of a hybrid with line 5 has also been obtained for another gene from chromosome 1R — Pgi2 (recombination with the S1 locus of 16.7%). By using the same method it has been estimated that line 4 has a self-fertility allele of the S2 locus from chromosome 2R and that the genes -Glu and Est4/11 are linked with it (recombination 16.7% and 17.5–20% respectively). Lines 2 and 3 have a self-fertility allele of the S5 locus from chromosome 5R which is linked with the Est5-7 gene complex (recombination at a level of 28.8–36.0%).     

Sequence variation at theSec-1 locus of rye,Secale cereale (Poaceae)

This paper describes the structure of a 9.2-kb repeat unit of DNA, which represents one-secalin gene and spacer sequence located at theSec-1 locus on the short arm of chromosome 1 of rye. The gene units at theSec-1 locus comprise 1.1 kb representing the gene and 8.1 kb of spacer sequence separating the genes. A sequence comparison of nine genes and their promoter regions from theSec-1 locus, reveals that there is greater variation within the coding sequence than there is within the promoter regions. The gene sequence variation is discussed in terms of the size variation seen for the-secalin proteins in rye species. The results include a comparison of promoter sequences from members of the Triticeae to examine the degree of conservation between other seed storage protein genes.