Endoplasmic Reticulum– and Golgi-Localized Phospholipase A2 Plays Critical Roles in Arabidopsis Pollen Development and Germination

Abstract

The phospholipase A₂ (PLA₂) superfamily of lipolytic enzymes is involved in a number of essential biological processes, such as inflammation, development, host defense, and signal transduction. Despite the proven involvement of plant PLA₂s in many biological functions, including senescence, wounding, elicitor and stress responses, and pathogen defense, relatively little is known about plant PLA₂s, and their genes essentially remain uncharacterized. We characterized three of four Arabidopsis thaliana PLA₂ paralogs (PLA₂-β, -γ, and -δ) and found that they (1) are expressed during pollen development, (2) localize to the endoplasmic reticulum and/or Golgi, and (3) play critical roles in pollen development and germination and tube growth. The suppression of PLA₂ using the RNA interference approach resulted in pollen lethality. The inhibition of pollen germination by pharmacological PLA₂ inhibitors was rescued by a lipid signal molecule, lysophosphatidyl ethanolamine. Based on these results, we propose that plant reproduction, in particular, male gametophyte development, requires the activities of the lipid-modifying PLA₂s that are conserved in other organisms.