Arabidopsis Dynamin-Related Protein 1a is important for cell plate fusion with parent cell plasma membrane in cytokinesis during pollen mitosis I.

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conclusionArabidopsis Dynamin-Related Protein 1a is important for mediating cell plate-parental membrane fusion during pollen mitosis I by regulating the formation of finger-like projections at the margin of the cell plate. Pollen mitosis I (PMI) is critical for pollen development, and the fusion of the cell plate with the parental plasma membrane is one of the most essential events during cytokinesis in PMI. However, the molecular mechanisms underlying this process remain largely unknown. In this study, we show that Arabidopsis Dynamin-Related Protein 1a (DRP1a), a multidomain GTPase regulating membrane remodeling processes such as fission, fusion, and tubulation, is required for cell plate fusion with the parental plasma membrane during PMI. Loss of DRP1a function leads to pollen abortion, with most drp1a mutant pollen grains failing to complete cell plate-parental membrane fusion. Further analysis revealed that in wild-type microspores, finger-like projections extend from the margins of the expanding cell plate and establish contact at the plasma membrane's adhesion zone. However, these structures were absent in cytokinesis-defective pollen grains from drp1a/ + mutants. Notably, DRP1a-YFP localized specifically to the cell plate margins, suggesting its direct involvement in this process. Our findings demonstrate that DRP1a, a member of the Dynamin-Related Protein family known for its roles in membrane remodeling, is important for mediating cell plate-parental membrane fusion during PMI by regulating the formation of finger-like projections.