The DNA glycosylase MBD4L contributes to DNA repair during seed development and germination

IGNACIO LESCANO; JOSÉ ROBERTO TORRES; FLORENCIA NOTA; NICOLÁS CECCHINI; MARIA ELENA ALVAREZ

Leiden

Workshop; Plant Genome Stability and Change; 2021

EMBO

Seed development and germination are coupled with cycles of dehydration and rehydration associated with high levels of reactive oxygen species, resulting in oxidation of DNA bases and strand breaks. Genome damage can be accumulated through time or exacerbated by stressful conditions (i.e. high temperatures) resulting in aged seeds with decreased vigor and viability. Consequently, DNA must be repaired prior germination to prevent genomic damage from being fixed after cell division. The base excision repair (BER) contributes to this end by using DNA glycosylases that excise damaged bases from the genome. Here, we first analyzed the seed phenotypes associated with the deficiency of the Arabidopsis DNA glycosylase MBD4L (methyl-binding domain protein 4 like). Both silique and seed size, as well as the germination rate were decreased in the MBD4L mutant (mdb4l) compared to the wild-type. The decreased germinationrate of mbd4l seeds was exacerbated after aging by long term storage at 22°C or short heat treatments at 37°C and 45°C. Germination rate under control and aging conditions were rescued by overexpressing MBD4L isoforms in the mutant background. Interestingly, seeds expressing the shorter isoform presented the highest germination rates. Comet assays and the expression pattern of BER genes showed that DNA repair was compromised in mbd4l mutants. Moreover, the promoter studies showed that MBD4L expression was higher at early stages during seed development. Our results suggest that MBD4L contributes to DNA repair by activating the BER system prior seed germination to maintain genome integrity and ensure cell survival and accurate transmission of genetic information.