Essential for the formation of class I meiotic crossovers. Interacts with PTD. Highest levels in young buds, where male meiosis occurs. Also present at low levels in plantlets, leaves, flowers, and roots. Reduction in the number of class I crossovers (COs) during meiosis (PubMed:18812090, PubMed:21771883). Impaired fertility due to altered male and female meiosis (PubMed:18812090). Belongs to the XPF family.