Maize XRCC2 participates in somatic DNA repair and meiotic crossover formation

The eukaryotic radiation sensitive 51 (RAD51) gene family comprises 7 ancient paralogs that have been remarkably conserved across both plants and animals. Among these paralogs, X-ray repair cross-complementing 2 (XRCC2) plays a pivotal role in mammalian embryonic development. However, in Arabidopsis (Arabidopsis thaliana), disruption of its function leads to seemingly normal meiotic processes, and intriguingly, even appears to increase meiotic recombination. Given these disparate observations, the precise role of XRCC2 during meiosis remains largely elusive. Here, we identified the XRCC2 gene in maize (Zea mays), a member of the RAD51 paralog family and the homolog of Arabidopsis XRCC2. Plants with mutated XRCC2 exhibited partial male and female sterility. Cytological investigations of xrcc2 mutants revealed that the meiocytes form univalent chromosomes and chromosome bridges and undergo chromosome fragmentation, while homologous pairing and synapsis occur normally. Notably, the xrcc2 mutant showed a significant reduction in the number of meiotic chiasmata and RAD51 foci. Furthermore, XRCC2 was essential for maintaining genome stability and affected the transcription of RAD51 paralogs. Within yeast and tobacco systems, we detected interactions between XRCC2 and disrupted meiotic cDNA1, radiation sensitive 51C, and radiation sensitive 51D. Collectively, XRCC2 demonstrates remarkable functional diversity across species and plays an important role in maize crossover formation.