Meiotic mutations in rye <i>Secale cereale</i> L.

Abstract

Spontaneous meiotic mutations of winter rye Secale cereale L. (2n = 14) were revealed in inbred F₂ progenies, which were obtained by self-pollination of F₁ hybrids resulting from crosses of individual plants of cultivar Vyatka or weedy rye with plants of self-fertile inbred lines. The mutations cause partial or complete sterility, and are maintained in heterozygote condition. Six types of mutations were distinguished as the result of cytological analysis of meiosis and genetic analysis. (1) Plants with nonallelic asynaptic mutations sy1 and sy9 lacked bivalents in 96.8 and 67.0% metaphase I cells, respectively, formed only axial elements but not the mature synaptonemal complex (SC), and had defects in telomere clustering in early prophase I. (2) Weak asynaptic mutant sy3 showed incomplete synapsis at the start of SC degradation at diplotene and lower chiasma number; yet only 2% meiocytes lacked bivalents in MI. (3) Mutations sy2, sy6, sy7, sy8, sy10, and sy19 caused nonhomologous synapsis; i.e., a varying number of univalents and occasional multivalents were observed in MI, which was preceded by switches of pairing partners and fold-back synapsis at mid-prophase I. (4) Mutation mei6 led to the formation of protrusions and minor branched structures of the SC lateral elements. (5) Allelic mutations mei8 and mei8-10 caused irregular chromatin condensation along the chromosome length in prophase I, which was accompanied by chromosome sticking and fragmentation in MI. (6) Allelic mutations mei5 and mei10 determined chromosome supercondensation, caused the disturbance of meiotic spindle assembly, arrested meiosis at various stages but did not affect formation of the pollen wall, thus arrested meiocytes got covered with the pollen wall. Analysis of double mutants revealed recessive epistatic interactions for some mutations; the epistatic group was sy9 > sy1 > sy3 > sy19. This reflects the sequence of meiotic events controlled by the corresponding genes. The expression of sy2 and sy19 proved to be modified by additional genes. Most meiotic mutations found in rye have analogs in other plants.

Chromosome synapsis in Arabidopsis: analysis of the transverse filament protein ZYP1 reveals novel functions for the synaptonemal complex

“…A number of asynaptic and desynaptic mutants were identified and analyzed cytologically in a range of species including maize (Beadle 1930(Beadle , 1933Golubovskaya and Mashnenkov 1976;Maguire et al 1991;Nelson and Clary 1952), rye (reviewed in Sosnikhina et al 2005), tomato (Havekes et al 1994), and Arabidopsis (Ross et al 1997). Mutations which result in varying degrees of nonhomologous, as opposed to homologous, synapsis were also described (Golubovskaya et al 1997(Golubovskaya et al , 2002Jenkins and Okumus 1992;Pawlowski et al 2004;Sosnikhina et al 2005;Timopheeva and Golubovskaya 1991). Recently, the gene encoding poor homologous synapsis (PHS1) was cloned from maize using the Mutator transposon tagging system (Pawlowski et al 2004).…”

The cytogenetics of homologous chromosome pairing in meiosis in plants

“…However, very few of these genes have sequence homologs in other groups of eukaryotes, including plants, suggesting that even though the overall bouquet structure is conserved, specific aspects of telomere clustering evolve more quickly. In plants, several mutants showing bouquet defects are known, including pam1 , dy1 , dsy1 , afd1 , and phs1 in maize, and sy1 in rye (Golubovskaya et al, 2002(Golubovskaya et al, , 2006Bass et al, 2003;Pawlowski et al, 2004;Sosnikhina et al, 2005). However, since the causes underlying nearly all these mutations are unknown, it is not clear which of these mutants represent specific bouquet defects and which are primarily defective in other meiotic processes, such as recombination, but also affect telomere clustering.…”

ASY1 coordinates early events in the plant meiotic recombination pathway

“…This potential has recently been demonstrated. A number of asynaptic and desynaptic mutants have been identified and analyzed cytologically in various plant species including maize (Golubovskaya and Mashnenkov, 1976), rye (reviewed in Sosnikhina et al, 2005) and tomato (Havekes et al, 1994). However, the lack of molecular information and genetic tools in these species is generally a serious limitation in the analysis of these synaptic mutants.…”

“…However, the lack of molecular information and genetic tools in these species is generally a serious limitation in the analysis of these synaptic mutants. A number of spontaneous meiotic mutations of winter rye, Secale cereale L., with abnormal synapsis have previously been described (reviewed in Sosnikhina et al, 2005). Immunolocalization studies using anti-ASY1 antibody on chromosome spread preparations of one rye mutant, sy10, has permitted its asynaptic behaviour to be analysed in detail (Mikhailova et al, 2006).…”