| Summary: | Apomictic plants (reproducing via asexual seeds), unlike sexual individuals, avoid meiosis and egg cell fertilization. Consequently, apomixis is very important for fixing maternal genotypes in the next plant generations. Despite the progress in the study of apomixis, molecular and genetic regulation of the latter remains poorly understood. So far <i>APOLLO</i> gene encoding aspartate glutamate aspartate aspartate histidine exonuclease is one of the very few described genes associated with apomixis in <i>Boechera</i> species. The centromere-specific histone H3 variant encoded by <i>CENH3</i> gene is essential for cell division. Mutations in <i>CENH3</i> disrupt chromosome segregation during mitosis and meiosis since the attachment of spindle microtubules to a mutated form of the <i>CENH3</i> histone fails. This paper presents in silico characteristic of <i>APOLLO</i> and <i>CENH3</i> genes, which may affect apomixis. Furthermore, we characterize the structure of <i>CENH3</i> by bioinformatic tools, study expression levels of <i>APOLLO</i> and <i>CENH3</i> transcripts by Real-Time Polymerase Chain Reaction RT-PCR in gynoecium/siliques of the natural diploid apomictic and sexual <i>Boechera</i> species at the stages of meiosis and before and after fertilization. While <i>CENH3</i> was a single copy gene in all <i>Boechera</i> species, the <i>APOLLO</i> gene have several polymorphic alleles associated with sexual and apomictic reproduction in the <i>Boechera</i> genera. Expression of the <i>APOLLO</i> apo-allele during meiosis was upregulated in gynoecium of apomict <i>B. divaricarpa</i> downregulating after meiosis until the 4th day after pollination (DAP). On the 5th DAP, expression in apomictic siliques increased again. In sexual <i>B. stricta</i> gynoecium and siliques <i>APOLLO</i> apo-allele did not express. Expression of the <i>APOLLO</i> sex-allele during and after meiosis in gynoecium of sexual plants was several times higher than that in apomictic gynoecium. However, after pollination the sex-allele was downregulated in sexual siliques to the level of apomicts and increased sharply on the 5th DAP, while in apomictic siliques it almost did not express. At the meiotic stage, the expression level of <i>CENH3</i> in the gynoecium of apomicts was two times lower than that of the sexual <i>Boechera</i>, decreasing in both species after meiosis and keep remaining very low in siliques of both species for several days after artificial pollination until the 4th DAP, when the expression level raised in sexual <i>B. stricta</i> siliques exceeding 5 times the level in apomictic <i>B. divaricarpa</i> siliques. We also discuss polymorphism and phylogeny of the <i>APOLLO</i> and <i>CENH3</i> genes. The results obtained may indicate to a role of the <i>CENH3</i> and <i>APOLLO</i> genes in the development of apomixis in species of the genus <i>Boechera</i>.
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