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PubMed1989

Mating system in rye: variability in relation to the population and plant density.

The amount of outcrossing was estimated using seven enzyme loci assayed in seven populations of rye (Secale cereale L.). Single-locus outcrossing values fluctuated widely from locus to locus in each population. The weighted mean single-locus estimates ranged from 0.716 to 0.946, and multilocus estimates ranged from 0.701 to 0.910. The analysis showed that self-pollination occurred in the rye populations, and, as a result of selfing, populations contained homozygotes in excess of random mating expectations at the seedling stage of development. Low plant density, which causes low pollen density during fertilization, seems to weaken the self-incompatibility system; at low plant density, the outcrossing estimate was significantly lower than was obtained at high plant density.

Breeding↗
PubMed1995

Synaptic patterns of rye B chromosomes. IV. The B isochromosomes.

Pairing of B isochromosomes in rye was studied by surface spreading of synaptonemal complexes in pollen mother cells from plants containing one small iso-B (iso-BS), one large iso-B (iso-BL), two iso-BL, one iso-BS plus one standard B (iso-BS+stB), one iso-BS plus two standard Bs (iso-BS + 2 stB) and one iso-BL plus two standard Bs (iso-BL + 2 stB). The main characteristics of iso-Bs were as follows. (1) Their location in the surface-spread nuclei was peripheral. (2) Their period of pairing relative to that of the A-set was delayed. (3) The commonest pachytene configuration was a symmetrical hairpin loop, although they could also undergo nonhomologous synapsis. (4) Synapsis could start at the chromosome ends, at the putative centromeric region or at both regions more or less simultaneously. (5) The frequency of iso-BL bivalents was only 46 per cent rather than the 66 per cent predicted by the random-end-pairing model. Interchromosomal pairing was frequent in these configurations. (6) In pairing competition situations involving three and four doses of the short arm of the standard B (iso-BS+stB, iso-BS + 2 stB), a large predominance of self-synapsed iso-BS univalents (63 per cent and 80 per cent respectively) was found. On the other hand, there was no apparent pairing preference among four doses of the long arm of the standard B in the iso-BL + 2 stB combination. Similarities and differences between the synaptic behaviours of iso-Bs of Crepis capillaris and Secale cereale are discussed.

Chromosomes↗
PubMedDate not supplied

The biophysical basis of cell elongation and organ maturation in coleoptiles of rye seedlings: implications for shoot development.

The relationships between changes in irreversible and reversible organ length, turgor (P), osmotic pressure (pi), and metabolic activity of the cells were investigated in intact coleoptiles of rye seedlings ( Secale cereale L.) that were either grown in darkness or irradiated with continuous white light. Cessation of growth at day 4 after sowing was associated with an apparent mechanical stiffening of the cell walls. Turgor pressure was measured in epidermal and mesophyll cells with a miniaturized pressure probe. No gradient of turgor was found between the peripheral and internal cells. In juvenile (growing) coleoptiles, average turgor was 0.60 MPa and a negative water potential (P - pi) was established in these cells. Upon emergence of the primary leaf, turgor declined, but P was maintained at values of 0.43 and 0.52 MPa in 7-day-old light- and dark-grown coleoptiles, respectively. Water potential in non-growing cells approached zero. The rate of dark respiration and elongation growth were not correlated. Surgical removal of the mature coleoptile revealed that the erect position of the 7-day-old shoot was dependent on the presence of this sturdy, turgid organ sheath. It is concluded that, during the first week of seedling development, the pierced, metabolically active coleoptile fulfills an essential function as an elastic basal tube for the juvenile shoot.

Cell Wall↗
PubMed2006

Phytostabilization of gold mine tailings, New Zealand. Part 1: Plant establishment in alkaline saline substrate.

Tailings from the Macraes mine, southern New Zealand, are prone to wind erosion. Use of a vegetation cover for physical stabilization is one potential solution to this environmental problem. This study used field trials contained in lysimeters to 1), test the ability of different plant species to grow in un/amended tailings and 2), provide background information on the nutrient and chemical content of waters in tailings. Barley (Hordeum vulgare), blue lupin (Lupinus angustifolius), and rye corn (Secale cereale) were trialed, using Superphosphate fertilizer and sewage sludge as amendments. Rye corn grew well in fertilizer-amended tailings, but poorly in unamended tailings; barley growth was similar in amended and unamended tailings; blue lupins grew poorly overall The tailings had alkaline pH (7-8.5) and water rapidly (< 1 mo) interacted with the tailings to become strongly saline. Minor acid generation was neutralized by calcite, with associated release of calcium and carbonate ions. Leachate waters were supersaturated with respect to calcite and dolomite. Dissolved sodium concentrations were up to 1000 mg L(-1), but elevated Ca2+ calcium and Mg2+ ensured that sodicity was lower than plant-toxic levels. Rye corn is a potentially useful plant for rapid phytostabilization of tailings, with only minor phosphate amendment required.

Biomass↗
PubMed2006

Phytostabilization of gold mine tailings from New Zealand. Part 2: Experimental evaluation of arsenic mobilization during revegetation.

Revegetation of mine tailings usually requires amendments of phosphorus. However, phosphate addition can mobilize arsenic (As) from the tailings. A 5-mo lysimeter field trial was conducted to quantify As mobilization in gold mine tailings, in association with different P amendment products and different plant species (barley Hordeum vulgare, blue lupin Lupinus angustifolius, rye corn Secale cereale) necessary for short-term revegetation of mine tailings. A simultaneous laboratory experiment was run to examine As mobilization in 1-cm-deep tailings in relation to different P amendment rates. The experimental results showed that the amount of As leached was proportional to the amount of P added. In the larger scale lysimeters, P amendment of < 3 g m(-2) caused As leaching of 0.5 mg L(-1) from unplanted lysimeters and up to 0.9 mg L(-1) on average in planted lysimeters. Variable species-amendment combinations produced differences in the amount of As leached and uptaken. Leachates and uptakes were higher with an organic fertilizer amendment than Superphosphate, particularly in combination with barley. Arsenic accumulated in plant biomass to 126 mg kg(-1) in shoots and 469 mg kg(-1) in roots.

Arsenic↗
PubMedDate not supplied

White yellow virescent pattern in winter rye: inheritance, plant growth, and ultrastructure of plastids.

Inbred lines from different varieties of cultivated plants characterized by a white yellow irregular pattern on the leaves obtained after selection in the inbred generation (S3) of winter rye (Secale cereale L.) were the object of the present studies. The feature of a white yellow irregular pattern in all lines was monomeric and recessive. This trait in L158b, wch, and zp was determined by the same recessive gene marked with the symbol wyv1, "white yellow virescent." The gene responsible for the appearance of the above feature in line L24 was nonallelic to the gene wyv1, therefore it was designated as the sequent gene of the same series--wyv2. The studied forms of plants were characterized by a diminution in the number of plastids and in chlorophyll (a plus b) content in mesophyll cells of leaves. Contrary to typical ultrastructure of chloroplasts in dark green plants (control), plastids in lines with the white yellow virescent pattern on the leaves showed variations in ultrastructure from numerous granal and intergranal thylakoids to a reduced number.

Chlorophyll↗
PubMed2002

The gravitropic setpoint angle of dark-grown rye seedlings and the role of ethylene.

The orientation growth of coleoptiles of dark-grown seedlings of rye (Secale cereale L. cv. Marder II), when grown under various conditions, was analysed with respect to the gravivector ('gravitropic setpoint angle', GSA). Coleoptiles growing through moist vermiculite attain and maintain a GSA with an average of about 180 degrees, i.e. a vertical orientation. Seedlings growing uncovered either on the surface of vermiculite or positionally fixed on filter paper attain and maintain a GSA of 140-150 degrees (i.e. deviating from the vertical by an average of 30-40 degrees ). Changing the position of the embryo relative to the horizontally fixed seed kernel or of the angle of the seed with respect to gravity during germination (+/-40 degrees relative to the horizontal) had no significant effect on the subsequent GSA of both covered and uncovered seedlings. The GSA of uncovered coleoptiles could be restored close to 180 degrees by treatment of the seedlings with ethylene, either applied via ethephon or 1-aminocyclopropane-1-carboxylic acid (ACC) as well as by fruit-released ethylene. The results are discussed with respect to the mechanism of the regulation of gravitropic growth of grass seedlings.

Amino Acids, Cyclic↗
PubMed2004

Uptake and translocation of phytochemical 2-benzoxazolinone (BOA) in radish seeds and seedlings.

The molecular aspects of phytochemical interactions between plants, especially the process of phytochemical translocation by the target plant, remain challenging for those studying allelopathy. 2-Benzoxazolinone (BOA) is a natural chemical produced by rye (Secale cereale) and is known to have phytotoxic effects on weed seeds and seedlings. The translocation of BOA into target plants has been poorly investigated. Therefore, the total absorption of [ring U 14C] BOA was estimated by oxidizing whole seedlings of Raphanus sativus cv. for 8 days and quantifying the radioactivity. Non-radiolabelled BOA in seedlings was also estimated by HPLC. BOA applied at 10(-3) M was readily taken up by germinated radish at a rate of 1556 nmol g(-1) FW. At these same concentrations, BOA reduced radish germination by 50% and caused a delay in radicle elongation. Exogenous BOA was responsible for the observed germination inhibition. At a concentration of 10(-5) M, BOA was taken up by germinated seeds (31 nmol g(-1) FW), but this quantity did not affect radish germination. Labelled BOA was not mineralized in the culture medium during seedling growth as no 14CO2 was recovered. Both 10(-3) and 10(-5) M BOA were translocated into radish organs, mainly into roots and cotyledons. These organs were then identified as potential physiological target sites. Cotyledons remained the target sink (44% of the total radioactivity). The kinetics of BOA uptake at 10(-3) and 10(-5) M in radish seedlings was identical: BOA accumulation was proportional to its initial concentration. A comparison between radioactivity and HPLC quantification for 10(-3) M BOA indicated that BOA (along with some metabolites) could effectively be recovered in radish organs using chromatography.

Benzoxazoles↗
PubMed1988

Uptake of 226Ra by established vegetation and black cutworm larvae, Agrotis ipsilon (class Insecta: order Lepidoptera), on U mill tailings at Elliot Lake, Canada.

Radium-226 levels in samples from an inactive U tailings site at Elliot Lake, Ontario, Canada, were: 9,140 +/- 500 mBq g-1 dry weight in the substrate; 62 +/- 1 mBq g-1 dry weight in rye, Secale cereale, and less than 3.7 mBq g-1 dry weight in oats, Avena sativa, the dominant species established by revegetation of the tailings; and 117 +/- 7 mBq g-1 dry weight in washed and unwashed black cutworm larvae. Concentration ratios were: vegetation to tailings 0.001-0.007; black cutworms to vegetation 3.6 and black cutworms to tailings 0.01. The values are considered too low to be considered a hazard to herring gulls, Larus argentatus, which occasionally feed on cutworms.

Animals↗
PubMed2004

Evidence for 'cross-talk' between A and B chromosomes of rye.

Spontaneous DNA insertions from supernumerary B chromosomes (Bs) into the standard A chromosome complement were detected in rye (Secale cereale L.), using fluorescent in situ hybridization (FISH) analysis with the D1100 B-specific sequence probe. The insertions were seen in individuals derived from plants possessing deleted Bs, characterized in this study by not having the B-specific sequences that are normally found at the distal part of the long arm of the standard rye B. This result supports the case for the spontaneous introgression of B-specific DNA into the A chromosome genome, and it indicates that 'cross-talking' between A and B chromosomes may occur in wild populations.

Chromosomes, Plant↗
PubMed2002

Cold-regulated cereal chloroplast late embryogenesis abundant-like proteins. Molecular characterization and functional analyses.

Cold acclimation and freezing tolerance are the result of complex interaction between low temperature, light, and photosystem II (PSII) excitation pressure. Previous results have shown that expression of the Wcs19 gene is correlated with PSII excitation pressure measured in vivo as the relative reduction state of PSII. Using cDNA library screening and data mining, we have identified three different groups of proteins, late embryogenesis abundant (LEA) 3-L1, LEA3-L2, and LEA3-L3, sharing identities with WCS19. These groups represent a new class of proteins in cereals related to group 3 LEA proteins. They share important characteristics such as a sorting signal that is predicted to target them to either the chloroplast or mitochondria and a C-terminal sequence that may be involved in oligomerization. The results of subcellular fractionation, immunolocalization by electron microscopy and the analyses of target sequences within the Wcs19 gene are consistent with the localization of WCS19 within the chloroplast stroma of wheat (Triticum aestivum) and rye (Secale cereale). Western analysis showed that the accumulation of chloroplastic LEA3-L2 proteins is correlated with the capacity of different wheat and rye cultivars to develop freezing tolerance. Arabidopsis was transformed with the Wcs19 gene and the transgenic plants showed a significant increase in their freezing tolerance. This increase was only evident in cold-acclimated plants. The putative function of this protein in the enhancement of freezing tolerance is discussed.

Acclimatization↗
PubMed2002

Expressed sequence tag-based gene expression analysis under aluminum stress in rye.

To understand the mechanisms responsible for aluminum (Al) toxicity and tolerance in plants, an expressed sequence tag (EST) approach was used to analyze changes in gene expression in roots of rye (Secale cereale L. cv Blanco) under Al stress. Two cDNA libraries were constructed (Al stressed and unstressed), and a total of 1,194 and 774 ESTs were generated, respectively. The putative proteins encoded by these cDNAs were uncovered by Basic Local Alignment Search Tool searches, and those ESTs showing similarity to proteins of known function were classified according to 13 different functional categories. A total of 671 known function genes were used to analyze the gene expression patterns in rye cv Blanco root tips under Al stress. Many of the previously identified Al-responsive genes showed expression differences between the libraries within 6 h of Al stress. Certain genes were selected, and their expression profiles were studied during a 48-h period using northern analysis. A total of 13 novel genes involved in cell elongation and division (tonoplast aquaporin and ubiquitin-like protein SMT3), oxidative stress (glutathione peroxidase, glucose-6-phosphate-dehydrogenase, and ascorbate peroxidase), iron metabolism (iron deficiency-specific proteins IDS3a, IDS3b, and IDS1; S-adenosyl methionine synthase; and methionine synthase), and other cellular mechanisms (pathogenesis-related protein 1.2, heme oxygenase, and epoxide hydrolase) were demonstrated to be regulated by Al stress. These genes provide new insights about the response of Al-tolerant plants to toxic levels of Al.

Adaptation, Physiological↗
PubMed2004

Calcium interacts with antifreeze proteins and chitinase from cold-acclimated winter rye.

During cold acclimation, winter rye (Secale cereale) plants accumulate pathogenesis-related proteins that are also antifreeze proteins (AFPs) because they adsorb onto ice and inhibit its growth. Although they promote winter survival in planta, these dual-function AFPs proteins lose activity when stored at subzero temperatures in vitro, so we examined their stability in solutions containing CaCl2, MgCl2, or NaCl. Antifreeze activity was unaffected by salts before freezing, but decreased after freezing and thawing in CaCl2 and was recovered by adding a chelator. Ca2+ enhanced chitinase activity 3- to 5-fold in unfrozen samples, although hydrolytic activity also decreased after freezing and thawing in CaCl2. Native PAGE, circular dichroism, and Trp fluorescence experiments showed that the AFPs partially unfold after freezing and thawing, but they fold more compactly or aggregate in CaCl2. Ruthenium red, which binds to Ca(2+)-binding sites, readily stained AFPs in the absence of Ca2+, but less stain was visible after freezing and thawing AFPs in CaCl2. We conclude that the structure of AFPs changes during freezing and thawing, creating new Ca(2+)-binding sites. Once Ca2+ binds to those sites, antifreeze activity, chitinase activity and ruthenium red binding are all inhibited. Because free Ca2+ concentrations are typically low in the apoplast, antifreeze activity is probably stable to freezing and thawing in planta. Ca2+ may regulate chitinase activity if concentrations are increased locally by release from pectin or interaction with Ca(2+)-binding proteins. Furthermore, antifreeze activity can be easily maintained in vitro by including a chelator during frozen storage.

Acclimatization↗
PubMed2005

Antifreeze proteins modify the freezing process in planta.

During cold acclimation, winter rye (Secale cereale L. cv Musketeer) plants accumulate antifreeze proteins (AFPs) in the apoplast of leaves and crowns. The goal of this study was to determine whether these AFPs influence survival at subzero temperatures by modifying the freezing process or by acting as cryoprotectants. In order to inhibit the growth of ice, AFPs must be mobile so that they can bind to specific sites on the ice crystal lattice. Guttate obtained from cold-acclimated winter rye leaves exhibited antifreeze activity, indicating that the AFPs are free in solution. Infrared video thermography was used to observe freezing in winter rye leaves. In the absence of an ice nucleator, AFPs had no effect on the supercooling temperature of the leaves. However, in the presence of an ice nucleator, AFPs lowered the temperature at which the leaves froze by 0.3 degrees C to 1.2 degrees C. In vitro studies showed that apoplastic proteins extracted from cold-acclimated winter rye leaves inhibited the recrystallization of ice and also slowed the rate of migration of ice through solution-saturated filter paper. When we examined the possible role of winter rye AFPs in cryoprotection, we found that lactate dehydrogenase activity was higher after freezing in the presence of AFPs compared with buffer, but the same effect was obtained by adding bovine serum albumin. AFPs had no effect on unstacked thylakoid volume after freezing, but did inhibit stacking of the thylakoids, thus indicating a loss of thylakoid function. We conclude that rye AFPs have no specific cryoprotective activity; rather, they interact directly with ice in planta and reduce freezing injury by slowing the growth and recrystallization of ice.

Acclimatization↗
PubMed2006

Molecular and structural characterization of hexameric beta-D-glucosidases in wheat and rye.

The wheat (Triticum aestivum) and rye (Secale cereale) beta-D-glucosidases hydrolyze hydroxamic acid-glucose conjugates, exist as different types of isozyme, and function as oligomers. In this study, three cDNAs encoding beta-D-glucosidases (TaGlu1a, TaGlu1b, and TaGlu1c) were isolated from young wheat shoots. Although the TaGlu1s share very high sequence homology, the mRNA level of Taglu1c was much lower than the other two genes in 48- and 96-h-old wheat shoots. The expression ratio of each gene was different between two wheat cultivars. Recombinant TaGlu1b expressed in Escherichia coli was electrophoretically distinct fromTaGlu1a and TaGlu1c. Furthermore, coexpression of TaGlu1a and TaGlu1b gave seven bands on a native-PAGE gel, indicating the formation of both homo- and heterohexamers. One distinctive property of the wheat and rye glucosidases is that they function as hexamers but lose activity when dissociated into smaller oligomers or monomers. The crystal structure of hexameric TaGlu1b was determined at a resolution of 1.8 A. The N-terminal region was located at the dimer-dimer interface and plays a crucial role in hexamer formation. Mutational analyses revealed that the aromatic side chain at position 378, which is located at the entrance to the catalytic center, plays an important role in substrate binding. Additionally, serine-464 and leucine-465 of TaGlu1a were shown to be critical in the relative specificity for DIMBOA-glucose (2-O-beta-D-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one) over DIBOA-glucose (7-demethoxy-DIMBOA-glucose).

Amino Acid Sequence↗
PubMed2006

Cold-active winter rye glucanases with ice-binding capacity.

Extracellular pathogenesis-related proteins, including glucanases, are expressed at cold temperatures in winter rye (Secale cereale) and display antifreeze activity. We have characterized recombinant cold-induced glucanases from winter rye to further examine their roles and contributions to cold tolerance. Both basic beta-1,3-glucanases and an acidic beta-1,3;1,4-glucanase were expressed in Escherichia coli, purified, and assayed for their hydrolytic and antifreeze activities in vitro. All were found to be cold active and to retain partial hydrolytic activity at subzero temperatures (e.g. 14%-35% at -4 degrees C). The two types of glucanases had antifreeze activity as measured by their ability to modify the growth of ice crystals. Structural models for the winter rye beta-1,3-glucanases were developed on which putative ice-binding surfaces (IBSs) were identified. Residues on the putative IBSs were charge conserved for each of the expressed glucanases, with the exception of one beta-1,3-glucanase recovered from nonacclimated winter rye in which a charged amino acid was present on the putative IBS. This protein also had a reduced antifreeze activity relative to the other expressed glucanases. These results support the hypothesis that winter rye glucanases have evolved to inhibit the formation of large, potentially fatal ice crystals, in addition to having enzymatic activity with a potential role in resisting infection by psychrophilic pathogens. Glucanases of winter rye provide an interesting example of protein evolution and adaptation aimed to combat cold and freezing conditions.

Amino Acid Sequence↗
PubMed1995

Levels of a terpenoid glycoside (blumenin) and cell wall-bound phenolics in some cereal mycorrhizas.

Four cereals, Hordeum vulgare (barley), Triticum aestivum (wheat), Secale cereal (rye), and Avena sativa (oat), were grown in a defined nutritional medium with and without the arbuscular mycorrhizal fungus Glomus intraradices. Levels of soluble and cell wall-bound secondary metabolites in the roots of mycorrhizal and nonmycorrhizal plants were determined by high-performance liquid chromatography during the first 6 to 8 weeks of plant development. Whereas there was no difference in the levels of the cell wall-bound hydroxycinnamic acids, 4-coumaric and ferulic acids, there was a fungus-induced change of the soluble secondary root metabolites. The most obvious effect observed in all four cereals was the induced accumulation of a terpenoid glycoside. This compound was isolated and identified by spectroscopic methods (nuclear magnetic resonance, mass spectrometry) to be a cyclohexenone derivative, i.e. blumenol C 9-O-(2'-O-beta-glucuronosyl)-beta-glucoside. The level of this compound was found to be directly correlated with the degree of root colonization.

Avena↗
PubMed1995

Antifreeze proteins in winter rye are similar to pathogenesis-related proteins.

The ability to control extracellular ice formation during freezing is critical to the survival of freezing-tolerant plants. Antifreeze proteins, which are proteins that have the ability to retard ice crystal growth, were recently identified as the most abundant apoplastic proteins in cold-acclimated winter rye (Secale cereale L.) leaves. In the experiments reported here, amino-terminal sequence comparisons, immuno-cross-reactions, and enzyme activity assays all indicated that these antifreeze proteins are similar to members of three classes of pathogenesis-related proteins, namely, endochitinases, endo-beta-1,3-glucanases, and thaumatin-like proteins. Apoplastic endochitinases and endo-beta-1,3-glucanases that were induced by pathogens in freezing-sensitive tobacco did not exhibit antifreeze activity. Our findings suggest that subtle structural differences may have evolved in the pathogenesis-related proteins that accumulate at cold temperatures in winter rye to confer upon these proteins the ability to bind to ice.

Adaptation, Biological↗