Abstract
Development of the male gametophyte is a tightly regulated process that requires precise control of cell division and gene expression. A relevant aspect to understand the events underlying pollen development regulation constitutes the identification and characterization of the genes required for this process. In this work we showed that the DC1 domain protein BINUCLEATE POLLEN (BNP) is essential for pollen development and germination. Pollen grains carrying the defective BNP allele failed to complete mitosis II and are impaired in pollen germination. By yeast two hybrid screening and bimolecular fluorescence complementation assays, we identified a set of BNP-interacting proteins. Among confirmed interactors we found NAC family transcriptional regulators Vascular plant One-Zinc finger 1 (VOZ1) and VOZ2. BNP and VOZ1/2 proteins were mainly detected co-localized in prevacuolar compartments. As voz1voz2 double mutants showed the same developmental defect observed in bnp pollen grains, we propose that BNP requirement to complete microgametogenesis could be linked to its interaction with VOZ1/2 proteins. By studying VOZ1 localization in pollen from bnp/BNP plants, we showed that VOZ1 nuclear localization requires BNP. We propose that BNP is acting as a scaffold protein recruiting VOZ1 and likely VOZ2 to prevacuolar compartments into assemblies that could modulate VOZ1/2 translocation to the nucleus and therefore modulate their activity as transcriptional regulators.
One sentence summary The DC1 domain protein BNP is required for pollen development and germination by mediating NAC transcription factors VOZ1/2 nuclear localization.