Phospholipase D Delta Regulates Pollen Tube Growth By Modulating Actin Cytoskeleton Organization In Arabidopsis

The actin cytoskeleton plays pivotal roles in pollen tube growth by regulating organelle movement, cytoplasmic streaming, and vesicle trafficking. Previous studies have reported that plasma membrane-localized phospholipase D delta (PLD delta) binds to cortical microtubules and negatively regulates plant stress tolerance. However, it remains unknown whether or how PLD delta regulates microfilament organization. In this study, we found that loss of PLD delta function led to a significant increase in pollen tube growth, whereas PLD delta overexpression resulted in pollen tube growth inhibition. We also found that wild-type PLD delta, rather than Arg 622-mutated PLD delta, complemented the pld delta phenotype in pollen tubes. In vitro biochemical assays demonstrated that PLD delta binds directly to F-actin, and immunofluorescence assays revealed that PLD delta in pollen tubes influences actin organization. Together, these results suggest that PLD delta participates in the development of pollen tube growth by organizing actin filaments.