[Effect of rye Secale cereale L. chromosomes 1R and 3R on polyembryony expression in hybrid combinations between (Hordeum vulgare L.)-Triticum aestivum L. alloplasmic recombinant lines and wheat T. aestivum L.-rye S. cereale L. substitution lines]

The effect of rye chromosomes on polyembryony was studied for reciprocal hybrid combinations between (Hordeum vulgare L.)-Triticum aestivum L. alloplasmic recombinant lines and five wheat T. aestivum L. (cultivar Saratovskaya 29)-rye Secale cereale L. (cultivar Onokhoiskaya) substitution lines: IR(1D), 2R(2D), 3R(3B), 5R(5A), and 6R(6A), and for direct hybrid combinations between the [H. marinum ssp. gussoneanum (H. geniculatum All.)]-T. aestivum alloplasmic recombinant line and the wheat-rye substitution lines 1R (1A), 1R (1D), and 3R(3B). Chromosomes 1R and 3R of rye cultivar Onokhoiskaya proved to affect the expression of polyembryony in the hybrid combinations that involved the alloplasmic recombinant lines of common wheat as maternal genotypes. Based on this finding, polyembryony was regarded as a phenotypic expression of nuclear-cytoplasmic interactions where an important role is played by rye chromosomes 1R and 3R and the H. vulgare cytoplasm. Consideration is given to the association between the effect of rye chromosomes 1R and 3R on polyembryony in the [(Hordeum)-T. aestivum x wheat-rye substitution lines] hybrid combinations and their stimulating effect on the development on angrogenic embryoids in isolated anther cultures of the wheat-rye substitution lines.

Rye (Secale cereale L.)

Rye (Secale cereale L.) is one of the most recalcitrant plant species for tissue culture and genetic transformation. Embryogenic rye callus loses its ability to regenerate plants quickly in response to high density of Agrobacterium and other stressors. The cocultivation of Agrobacterium and rye immature embryos in liquid medium facilitated washing of the cultures to avoid Agrobacterium overgrowth and allowed a high throughput. More than 40 independent transgenic plants were regenerated with one to four Southern-positive, independent events from 100 inoculated immature embryos. Agrobacterium strain AGL0 supported stable integration of a constitutive nptII selectable marker expression cassette into the genome of rye inbred line L22, as indicated by regeneration of plantlets on paromomycin-containing culture medium, Southern blot, Western blot, and the analysis of T-DNA::plant DNA boundary sequences. Transgenic plants were phenotypically normal and fully fertile, which might be a consequence of the short time in tissue culture.

[Transmission of 5R chromosomes via gametes and its influence on spring bread wheat somatic embryoidogenesis in vitro]

Transmission of chromosomes 5R and 5A via gametes and its effect on somatic embryoidogenesis have been studied with the use of the model 5R(5A) substitution line L2837 = L503/Secale cereale L., cultivar Saratovskaya 5/L503, where L503 is a cultivar of spring bread wheat. It has been found that the frequencies of transmission of univalent chromosomes 5R and 5A determined in experiments on F1 reciprocal hybrids with cultivar Saratovskaya 29 do not reflect their frequencies in the self-pollinated offspring of F1 hybrids; the frequency of transmission of chromosomes 5R and 5A depends on the genotypes of both the recipient cultivar and the donor rye cultivar; and the 5R(5A) substitution in cultivar L503 significantly increases the parameters of somatic embryoidogenesis in vitro in explants from inflorescences.

Somatic embryogenesis and fertile green plant regeneration from suspension cell-derived protoplasts of rye ( Secale cereale L.)

A method for somatic embryogenesis and fertile green plant regeneration from suspension cell-derived protoplasts of rye (Secale cereale L. cv. Auvinen) was developed. Fast-growing and friable embryogenic calli with a high regeneration capacity were induced from immature rye inflorescences using modified MS medium. These friable embryogenic calli were used for suspension culture initiation in liquid AA medium. A high yield of protoplasts was obtained from suspension cell clumps after 3-5 days of subculture. Isolated protoplasts were cultured in KM8p medium. The frequency of protoplast cell divisions and colony formations in liquid culture medium were similar to those on agarose-solidified medium. Compact embryogenic calli were developed from protoplast-derived microcalli in growth medium mMS. Approximately 7% of the transferred embryogenic calli produced green shoots on N6 regeneration medium. Of 33 green plants, 28 were fertile with normal flowering and seed set. The ratio of green and albino plantlets was 1:4. Rye protoplast-derived green plants showed normal diploid characters as determined by flow cytometer analysis and chromosome counting.

[Comparative effects of rye chromosomes 1R and 5R on androgenesis in cultured anthers of wheat-rye substitution lines dependending on the line origin]

The effects of rye chromosomes 1R and 5R on androgenesis in cultured anthers of wheat--rye substitution lines was studied as dependent on the cultivar origin of the rye chromosomes and on the wheat genome (A or D) subjected to substitution. Chromosome 1R stimulated embryogenesis in anther cultures, while chromosome 5R suppressed it regardless of whether the corresponding wheat chromosomes were substituted in the A or D genome. The effect of chromosome 1R on embryogenesis proved to depend on its cultivar origin. Along with rye chromosome 1R, wheat chromosome 1A was shown to substantially affect total seedling regeneration. Regeneration of green seedlings was dramatically affected both by rye chromosome 1R and by wheat chromosome 1D. The results supported the published data that individual androgenesis parameters (embryogenesis, total plant regeneration, green plant regeneration) are controlled by different genetic mechanisms.

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.

Antifungal activity of rye (Secale cereale) seed chitinases: the different binding manner of class I and class II chitinases to the fungal cell walls

The antifungal activities of rye seed chitinase-a (RSC-a, class I) and -c (RSC-c, class II) were studied in detail using two different bioassays with Trichoderma sp. as well as binding and degradation experiments with the cell walls prepared from its mycelia. RSC-a inhibited more strongly the re-extension of the hyphae, containing mainly mature cells, than RSC-c did. Upon incubation of the fungus with fluorescent chitinases, FITC-labeled RSC-a was found to be located in the hyphal tips, lateral walls, and septa, while FITC-labeled RSC-c was only in the hyphal tip. RSC-a had a greater affinity for the cell walls than RSC-c. RSC-a liberated a larger amount of reducing sugar from the cell walls than RSC-c did. These results inferred that RSC-a first binds to the lateral walls and septa, consisting of the mature cell walls, and degrades mature chitin fiber, while RSC-c binds only to the hyphal tip followed by degradation of only nascent chitin. As a result, RSC-a inhibited fungal growth more effectively than RSC-c. Furthermore, it was suggested that the chitin-binding domain in RSC-a assists the antifungal action of RSC-a by binding to the fungal hypha.

[Morphometric analysis of wheat and rye zygotes during maturation]

The size of cell, nucleus, and nucleolus was measured and the nucleus-to-nucleolus ratio was determined during zygote maturation in durum and soft wheat and rye under intravarietal pollination as well as under crossing of durum wheat with soft wheat and rye. The fluctuations of cell, nucleus, and nucleolus volumes during zygote maturation were observed. The curves percent ratio of these volumes to corresponding volume of egg cell have two peaks. There are differences between hybrid zygotes and parental forms in these indices.

Molecular cloning, functional expression, and mutagenesis of cDNA encoding rye (Secale cereale) seed chitinase-c

We cloned a complete cDNA encoding rye seed chitinase-c, designated RSC-c, by rapid amplification of cDNA end and PCR procedures. The cDNA of RSC-c consists of 1,018 nucleotides and includes an open reading frame encoding a polypeptide of 266 amino acid residues. A recombinant RSC-c was produced by expression in Escherichia coli Origami(DE3) and purified. rRSC-c had almost the same chitinase activity toward glycolchitin and antifungal activity against Trichoderma sp. as the authentic RSC-c did. RSC-c mutants were subsequently constructed and characterized with respect to their chitinase and antifungal activities. Mutation of Glu67 to Gln completely abolished the chitinase activity and diminished the antifungal activity. Considerable decreases in both activities were observed in the mutations of Trp72 and Ser120 to Ala, and Glu89 to Gln. The roles of these residues in the catalytic event of RSC-c are discussed.

Localization, accumulation, and antifungal activity of chitinases in rye (Secale cereale) seed

In order to understand a physiological role of chitinases in rye, the localization and accumulation of rye seed chitinase-a and -c (RSC-a and -c) in the seeds were studied by immunochemical methods. An antiserum specific to the chitin-binding domain (CB-domain), which is an N-terminal part of RSC-a, and an antiserum specific to the catalytic region of RSC-a and RSC-c were used. An immunoblot analysis detected both RSC-a and RSC-c in the endosperm of the rye seed. Immunohistochemical staining indicated that RSC-a was localized in only the aleurone cells, whereas RSC-c existed at least in the starchy endosperm and was also likely to exist in the aleurone cells. It was found by ELISA and an immunoblot analysis that RSC-a and -c accumulated in the seed during the later stage of development. Both chitinases and the Cat-domain exhibited antifungal activity toward Trichoderma species, while the CB-domain did not. Observation of the inhibition of hyphal growth of the T. species suggests that the two chitinases acted in different ways.

[Effect of rye chromosomes on features of androgenesis in wheat-rye substituted lines of Triticum aestivum L. sort Saratovskaya 29/Secale cerale L. sort Onokhoiskaia and Triticale]

The characteristic features of androgenesis in six wheat-rye substitution lines Triticum aestivum L. (cv. Saratovskaya 29)/Secale cereale L. (cv. Onokhoiskaya) and triticale (2n = 56) using anther culture at different concentrations of 2,4-D in the growth medium were studied. Under variable cultivation conditions, the significant effect of genotypic diversity on the variability of such androgenesis parameters as the frequency of productive anthers, the frequency of embryoid formation, and the frequency of total regenerated plantlets, was shown. It was demonstrated that chromosomes 1R, 3R, and 7R stimulated the formation of androgenous embryoids, while chromosome 5R produced an opposite effect. In triticale and substitution lines, the regeneration ability of androgenous embryoids induced by elevated 2,4-D concentrations was inhibited. Chromosome 1R of the Onokhoiskaya cultivar was suggested to contain genes suppressing regeneration of green plantlets, while chromosome 3R, conversely, stimulated their formation. Chromosomes 1R, 2R, 3R, and 7R of the Onokhoiskaya cultivar did not inhibit the spontaneous formation of androgenous hexaploids in the substitution lines.

Higher cardol homologs (5-alkylresorcinols) in rye seedlings

The occurrence of alkylresorcinols, polyketide compounds that in the same homologous series as cardol isolated from Anacardium occidentale (cashew) or bilobol from Ginkgo biloba which are derivatives of 1,3-dihydroxy-5-alk(en)ylbenzene, have been demonstrated in developing rye (Secale cereale L.) kernels. The 3-day-old seedlings grown in sterile conditions already contain detectable amounts of phenolic compounds that were identified as alkylresorcinols. This fraction is the mixture of saturated and enoic homologs of various lengths of the aliphatic side chain. The composition of homologs is similar to that determined in mature grains. The relatively high level of alkylresorcinols in mitochondria and plastids (enhanced approximately twice in the absence of light) suggests that their synthetic pathway and/or biological function may be related to these cellular compartments. Resorcinolic lipids, when present in the external medium, are taken up by seedlings in the energy-dependent manner.

Somaclonal variation in rye

We studied the genetic variation generated during in vitro culture of rye Secale cereale L. We analyzed the progenies of four generations of the plants regenerated from immature embryo cultures. A high frequency of mutant plants was observed, 50.75%, this frequency was genotype dependent. Other characteristics typical of somaclonal variation were also observed: the obtaining of dominant mutations, the presence of more than one mutation per plant, the obtaining of homozygous mutants and a high rate of mutation of particular loci. In some cases transposable elements could be implicated. We postulate that tissue culture could induce mutations as well as select particular cell types and so increase the appearance of special mutants.