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The recessive spontaneous sy18 mutation with nonhomologous synapsis was mapped in rye. The sy18 gene was located in the centromeric region of chromosome 2R in relation to three rye SSR (simple sequence repeats) loci, i.e., Xrems1130, Xrems1203, and Xscm43, and one wheat SSR locus Xgwm132. The desynaptic sy18 gene is located in the interval between Xrems1130 and Xrems1203 markers at a distance of 0.5 cM and 3.1 cM, respectively. The possible evolutionary relationships of the mapped gene with homologous loci of the related species are discussed.

A study was made of the expression and inheritance of the sy11 mutation, which alters homologous chromosome synapsis in meiotic prophase I of rye. The abnormal phenotype proved to be determined by a recessive allele of a single sy11 gene. Univalents and multivalents were observed in homozygotes for the mutant allele. Analysis of the synaptonemal complex revealed a combination of homologous and nonhomologous synapsis in the mutant. The nonhomologous synapsis frequency significantly decreased in the course of meiotic prophase I in the mutant. The number of chiasmata per bivalent in metaphase I was 1.1 x 0.01 versus 1.8 x 0.01 in wild-type plants, and the number of univalents was 2.7 x 0.06 versus 0.5 x 0.05 in wild-type plants. As a result, a broad range of abnormalities was observed at subsequent stages of meiosis and led to the formation of defective microspores. Mutant plants were semisterile.

Studies of phenotypical expression of synaptic mutations in combination with the localization of corresponding genes on a genetic map permit individual stages of the meiotic process to be differentiated. Two rye asynaptic genes, sy1 and sy9, were mapped with the use of microsatellite markers (SSR) in the pericentromeric regions of the long chromosome arms 7R and 2R, respectively. The sy9 gene cosegregated with two SSR markers Xscm43 and Xgwm132. The asynaptic gene sy1 was mapped within the interval between the isozyme locus Aat2 and two cosegregating loci Xrems1188 and Xrems1135 that are located at a distance of 0.4 cM proximally and 0.1 cM distally with respect to the gene lous. Possible evolutionary relationships of the mapped genes with homeological loci of the Triticeae species and more distant cereal species, such as maize and rice, are discussed.

Genetic collection of meiotic mutants of winter rye Secale cereale L. (2n = 14) was created. Mutations were detected in inbred F2 generations after self-fertilization of the F1 hybrids, obtained by individual crossing of rye plants (cultivar Vyatka) or weedy rye with plants from autofertile lines. The mutations cause partial or complete plant sterility and are maintained in collection in a heterozygous state. Genetic analysis accompanied by cytogenetic study of meiosis has revealed six mutation types. (1) Nonallelic asynaptic mutations sy1 and sy9 caused the formation of only axial chromosome elements in prophase and anaphase. The synaptonemal complexes (SCs) were absent, the formation of the chromosome "bouquet" was impaired, and all chromosomes were univalent in meiotic metaphase I in 96% (sy1) and 67% (sy2) of cells. (2) Weak asynaptic mutation sy3, which hindered complete termination of synapsis in prophase II. Subterminal asynaptic segments were always observed in the SC, and at least one pair of univalents was present in metaphase I, but the number of cells with univalents did not exceed 2%. (3) Mutations sy2, sy6, sy7, sy8, sy10, and sy19, which caused partially nonhomologous synapsis: change in pairing partners and fold-back chromosome synapsis in prophase I. In metaphase I, the number of univalents varied and multivalents were observed. (4) Mutation mei6, which causes the formation of ultrastructural protrusions on the lateral SC elements, gaps and branching of these elements. (5) Allelic mutations mei8 and mei10, which caused irregular chromatin condensation along chromosomes in prophase I, sticking and fragmentation of chromosomes in metaphase I. (6) Allelic mutations mei5 and mei10, which caused chromosome hypercondensation, defects of the division spindle formation, and random arrest of cells at different meiotic stages. However, these mutations did not affect the formation of microspore envelopes even around the cells, whose development was blocked at prophase I. Analysis of cytological pictures of meiosis in double rye mutants reveled epistatic interaction in the mutation series sy9 > sy1 > sy3 > sy19, which reflects the order of switching these genes in the course of meiosis. The expression of genes sy2 and sy19 was shown to be controlled by modifier genes. Most meiotic mutations found in rye have analogs in other plant species.

Data on linkage of 12 rye genes controlling morphological traits (el, Vs, ln, w, np, ct2, Hs, Ddw, cb, mn, vil, mp) with one or several isozyme markers of individual rye chromosomes (2R-7R) are presented. Linkage of the following gene pairs was established: chromosome 2R: Est3/5-el, el-beta-Glu, Sod2-el, Sod2-Vs; chromosome 3R: ln-Got4; chromosome 4R: w-Got1, np-Got1; chromosome 5R: Est4-ct2, Est6/9-ct2, ct2-Est2, ct2-Aco2, Est2-Hs, Aco2-Hs, Est2-Ddw, Aco2-Ddw; chromosome 6R: Lap2-cb, cb-Aco1, Est10-mn; chromosome 7R: Acph2/3-vi1, Got2-vi1, mp-Acph2/3. The reasons for mapping a very small number of genes in rye in spite of high intraspecific variability of this species are discussed. An approach is suggested to improve this situation by simultaneous identification and mapping of all diverse spontaneous mutations maintained in heterozygous state in various rye cultivars.

The genetic map of rye consisting of 149 RFLP, 20 isozyme and 12 microsatellite markers was developed. Using the collection of cross-hybridizing probes, the presence of multiple translocations in rye genome with respect to wheat and barley genomes was shown. However, within large regions of genome a strict collinearity of marker order was observed that allow us to use the method of comparative mapping for an introduction of new genes. In the developed genetic map 18 morphological and breeding-valuable genes mapped in different rye populations were integrated. The comparative analysis of homeological loci in genomes of Triticeae species as well as in genomes of rice and maize was carried out. The genes controlling a number of morphological traits, plant height, photoperiodic response and winter/spring growth habit were shown to be conserve among cereals and to form clear homoeologous rows.