RESUMO
The Peterhof Collection of spontaneous meiotic mutants of rye was used as a model to study the genetic control of meiosis key events in an organism with a large genome. A combination of methods, which included fluorescence in situ DNA-DNA hybridization, sequencing of recombinogenic proteins, and immunocytochemical analysis of meiosis proteins, clearly showed that mutation sy1 affects recombination events, asynapsis in mutant sy9 is connected with defects of the assembly of synaptonemal complex axial cores, and that synapsis defects in mutant sy10 are coupled with the presence of protein Zyp1 in the core region. The assembly of proteins Asyl and Zyp1 on the axes of meiotic chromosomes was shown to occur separately, which is a specific feature of rye, as compared to arabidopsis.
Assuntos
Cromossomos de Plantas/genética , Mutação , Recombinação Genética , Secale/genética , Complexo Sinaptonêmico/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Cromossomos de Plantas/metabolismo , Secale/metabolismo , Complexo Sinaptonêmico/metabolismoRESUMO
AExpression and inheritance of the sy18 mutation causing impairment of synapsis homology were studied. It was established that the abnormal phenotype is determined by a recessive allele of the sy18 gene. Univalents and multivalents are observed in homozygotes for this mutant allele. According to the electron microscopic analysis of synaptonemal complexes in mutants, homologous synapsis occurs together with nonhomologous synapsis. The sy18 gene was found to have no allelism with asynaptic genes sy1 and sy9 and with genes sy10 and sy19 causing, like sy18, disturbances in synapsis homology.
Assuntos
Alelos , Genes de Plantas/genética , Genes Recessivos/fisiologia , Mutação , Secale/genética , Complexo Sinaptonêmico/genética , Secale/metabolismo , Complexo Sinaptonêmico/metabolismoRESUMO
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.
Assuntos
Cromossomos de Plantas/genética , Evolução Molecular , Genes de Plantas/genética , Loci Gênicos/genética , Repetições de Microssatélites/genética , Secale/genética , Mapeamento Cromossômico , Grão Comestível/genética , Oryza/genética , Especificidade da Espécie , Zea mays/genéticaRESUMO
The cytological phenotype was studied in a desynaptic form isolated from a population of rye cultivar Vyatka. The primary defect of desynaptic plants was identified as nonhomologous (heterologous) chromosome synapsis, which was observed by electron microscopy of synaptonemal complexes (SCs) in meiotic prophase I. Synapsis defects involved switches of synapsing axial elements to nonhomologous partners, asynapsis in the switching region, and foldbacks formed by the SC lateral elements. Defective bivalent formation was observed at later stages: the univalent number varied and multivalent chromosome associations were observed in single cells in metaphase I. The desynaptic phenotype was controlled by two recessive genes, sy8a and sy8b, which acted and were inherited independently. In a hybrid combination with line Ku-2/63, the desynaptic phenotype was suppressed by the dominant allele of a third gene for inhibitor I; the segregation in hybrid families corresponded to 57:7.
