The 30th International Conference on Arabidopsis Research (ICAR 2019)

432 / 2019-01-29 04:40:15

Distinct requirements of RNA Polymerase IV in the Brassicaceae

RdDM,Pol IV,plant reproductive development

Plenary track > Epigenetics

In the canonical RNA-directed DNA methylation (RdDM) pathway, the biogenesis of 24-nucleotide small interfering RNAs (24nt-siRNAs) requires the plant-specific RNA polymerase IV (Pol IV). Loss of Pol IV function does not cause obvious developmental defects in Arabidopsis thaliana. In contrast, impaired POL IV function in Brassica rapa was reported to cause a maternally controlled defect of seed development. To test whether the requirement of Pol IV function during reproductive development is a conserved feature within Brassicaceae species having higher number of transposable elements than Arabidopsis thaliana, we generated a loss-of-function allele in the NRPD1a subunit of Pol IV in Capsella rubella. Consistent with the phenotype reported in Brassica, loss of Pol IV function in Capsella caused a maternally-controlled seed phenotype. Strikingly however, we also observed an arrest of pollen development after meiosis at the unicellular stage. Since we did not observe an obvious meiotic defect, we speculate that Pol IV is required post-meiotically at the unicellular stage to repress transposable elements. Our data highlight species-specific requirements of Pol IV function during plant reproductive development.