The DcPS1 cooperates with OSDLa during pollen development and 2n gamete production in carnation meiosis.

Background: Deciphering the mechanisms of meiosis has important implications for potential applications in plant breeding programmes and species evolution. However, the process of meiosis is poorly understood in carnation, which is famous for its cut flowers.

Results: We report that Dianthus caryophyllus parallel spindle 1 (DcPS1) regulates omission of second division like a (OSDLa) during pollen development and 2n gamete production in carnation meiosis. In DcPS1 and OSDLa RNAi lines, an absence of the second meiotic division and the abnormal orientation of spindles at meiosis II might be the main reason for dyad/triad formation, resulting in unreduced gametes. We also found that carnation OSDLa interacted with DcPS1 and DcRAD51D. In the DcPS1 RNAi lines, a decrease in OSDLa and DcRAD51D expression was observed. In the OSDLa RNAi lines, a decrease in DcPS1 and DcRAD51D expression was also observed. We propose that DcPS1 regulates OSDLa expression, allowing entry into meiosis II and the proper orientation of the metaphase II spindle in meiosis II. We also propose that OSDLa regulates DcRAD51D expression, allowing for homologous recombination.

Conclusions: These results suggest a critical role for DcPS1 and OSDLa in diplogamete production during meiosis and open a new pathway for meiosis-related studies.