Role of MSH6 during DNA recombination in Arabidopsis thaliana

GONZALEZ, VALENTINA; SPAMPINATO, CLAUDIA P.

Paraná

Congreso; LIV Reunión Anual de la Sociedad Argentina de Investigación Bioquímica (SAIB); 2018

SAIB

The mismatch repair (MMR) pathway promotes genome stability by increasing the fidelity of DNA replication and recombination. The initial step of the pathway requires heterodimers of MSH proteins. The MSH6-MSH2 heterodimer recognizes base-base mismatches and small insertion/deletion loops. To further understand the role of Arabidopsis MSH6 in vivo, we first generated transgenic plants expressing the β-glucuronidase (GUS) reporter gene under the control of the MSH6 promoter. Histochemical staining demonstrated that MSH6 is preferentially expressed in proliferating tissues. We then investigated protein function during meiotic and somatic recombination using previously described reporter assays. The meiotic tester line contains two reporter genes that encode green (GFP) and red (RFP) fluorescent proteins located at 16 cM under the regulation of a seed-specific promoter. Seeds with exclusively green or red fluorescence indicate a meiotic recombination event between the markers. The somatic recombination assay construct contains two overlapping halves of the GUS reporter gene (namely GU and US). Recombination between identical (homologous recombination) or 1.6% divergent (homeologous recombination) U repeats leads to the formation of an active GUS reporter gene. Disruption of MSH6 has no effect on the rate of meiotic recombination, but increased the frequency of homologous or homeologous recombination by 1.3- or 4-fold, respectively, relative to wild-type plants. We conclude that MSH6 plays an important role during somatic recombination in plants.