Isolation and characterisation of the RAD51 and DMC1 homologs from Arabidopsis thaliana

Abstract

By using RT-PCR and degenerate oligonucleotides based on the sequence homology between the yeast RAD51 and DMC1 genes, two genes belonging to the RAD51 and DMC1 families were isolated from Arabidopsis thaliana ecotype Columbia. A RAD51 genomic DNA was also sequenced which is almost identical to its Landsberg erecta counterpart, except for a few translationally silent substitutions and for the presence of a 527-bp element downstream of the polyadenylation site. This element is repeated in the genome of Arabidopsis. Northern analyses were conducted to characterize the expression pattern of both these genes. AtRAD51 and AtDMC1 are expressed in flower buds, but also in the mitotically active cells from a suspension culture. AtRAD51, but not AtDMC1, transcript level increases after gamma irradiation of the cells. Finally, a synchronisation experiment conducted with the suspension culture indicated that not only AtRAD51 but also AtDMC1 are regulated during the cell cycle, with S-phase-specific induction. Since DMC1 genes have always been regarded as being specifically meiotic, we discuss the significance of this mitotic transcriptional regulation in Arabidopsis.

Identification of PlantRAD52Homologs and Characterization of theArabidopsis thaliana RAD52-Like Genes

“…In plants, RAD51 (Doutriaux et al, 1998;Bleuyard et al, 2006) and RAD54 (Osakabe et al, 2006;Shaked et al, 2006) homologs have been identified, leaving the question of whether plants contain RAD52 homologs (Iyer et al, 2002;Mortensen et al, 2009) or whether their absence may be compensated for by two plant BRCA2 homologs (Siaud et al, 2004;Abe et al, 2009). Nevertheless, the absence of RAD52 in plants is somewhat intriguing, considering its role in mediating critical steps of homologous recombination and its relatively high conservation across eukaryotes.…”

Random Chromosome Segregation without Meiotic Arrest in Both Male and Female Meiocytes of a dmc1 Mutant of Arabidopsis

“…Finally, homozygous disruption of the DMC1 gene in mouse parallels some aspect of the yeast dmc1 mutations in that it also affects meiosis, although leading to apoptosis, which was not observed in yeast (Pittman et al, 1998;Yoshida et al, 1998). In Arabidopsis, an ortholog of the yeast DMC1 gene, AtDMC1 , has been described (Sato et al, 1995;Klimyuk and Jones, 1997;Doutriaux et al, 1998). It is a single-copy gene that is expressed in young flower buds when cells are undergoing meiosis.…”

Functional conservation of the meiotic genes SDS and RCK in male meiosis in the monocot rice

“…In addition to the conserved sequences and functions of rice SDS and RCK shown in this study, a small number of rice meiosis genes have been studied including PAIR2 [43], OsDMC1 [44], OsRad21-4 [45] and their functions in rice male meiosis are conserved compared to their correspondent homologous genes ASY1 [58], AtDMC1 [59,60], SYN1 [61] in Arabidopsis. In Arabidopsis, the ASY1 protein is localized to the axial/lateral elements and an asy1 mutant is asynaptic and unable to form SC in both male and female meiocytes, indicating its critical role in SC formation [54,58,62].…”