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

LESCANO I; TORRES J; NOTA MF; CECCHINI NM; ALVAREZ ME

Congreso; EMBO Workshop-Plant genome stability and change 2020; 2021

Seed development and germination are coupled with cycles ofdehydration and rehydration associated with high levels ofreactive oxygen species, resulting in oxidation of DNA bases andstrand breaks. Genome damage can be accumulated throughtime or exacerbated by stressful conditions (i.e. hightemperatures) resulting in aged seeds with decreased vigor andviability. Consequently, DNA must be repaired prior germinationto prevent genomic damage from being fixed after cell division.The base excision repair (BER) contributes to this end by usingDNA glycosylases that excise damaged bases from the genome.Here, we first analyzed the seed phenotypes associated with thedeficiency of the Arabidopsis DNA glycosylase MBD4L (methylbindingdomain protein 4 like). Both silique and seed size, as wellas 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 termstorage at 22°C or short heat treatments at 37°C and 45°C.Germination rate under control and aging conditions wererescued by overexpressing MBD4L isoforms in the mutantbackground. Interestingly, seeds expressing the shorter isoformpresented the highest germination rates. Comet assays and theexpression pattern of BER genes showed that DNA repair wascompromised in mbd4l mutants. Moreover, the promoter studiesshowed that MBD4L expression was higher at early stages duringseed development. Our results suggest that MBD4L contributesto DNA repair by activating the BER system prior seedgermination to maintain genome integrity and ensure cell survivaland accurate transmission of genetic information.