Exonuclease required for organelle DNA degradation during pollen development. Plays non-essential roles in maternal inheritance. May be part of the DNA salvage machinery. Inhibited by free nucleotide diphosphates (NDPs). Highly expressed in mature pollen grains. Detected in flowers, senescing leaves and roots. Starts to express at the bicellular pollen stage, with a peak at the tricellular pollen stage. No visible phenotype. DPD1 homologs are present in flowering plants but not in moss, green algae and animals. Belongs to the exonuclease superfamily. TREX family.