Lipid anchoring and electrostatic interactions target NOT-LIKE-DAD to pollen endo-plasma membrane

Abstract

Phospholipases cleave phospholipids, major membrane constituents. They are thus essential for many developmental processes, including male gamete development. In flowering plants, mutation of phospholipase NOT-LIKE-DAD (NLD, also known as MTL or ZmPLA1) leads to peculiar defects in sexual reproduction, notably the induction of maternal haploid embryos. Contrary to previous reports, NLD does not localize to cytosol and plasma membrane of sperm cells but to the pollen endo-plasma membrane (endo-PM), a specific membrane derived from the PM of the pollen vegetative cell that encircles the two sperm cells. After pollen tube burst, NLD localizes at the apical region of the egg apparatus. Pharmacological approaches coupled with targeted mutagenesis revealed that lipid anchoring together with electrostatic interactions are involved in the attachment of NLD to this atypical endo-PM. Membrane surface-charge and lipid biosensors indicated that phosphatidylinositol-4,5-bisphosphate is enriched in the endo-PM, uncovering a unique example of how membrane electrostatic properties can define a specific polar domain (i.e., endo-PM), which is critical for plant reproduction and gamete formation.

Absent daddy, but important father

“…1b)? Interestingly, contrary to previous reports 4,5 , the MTL/NLD/ZmPLA1 protein was recently demonstrated to not localize inside but outside of the sperm cells, on the poorly characterized endo-plasma membrane that encircles the sperm cells 9 (Fig. 1b).…”

Evaluation of genome and base editing tools in maize protoplasts

“…The maize ( Zea mays ) inbred line A188 ( Gerdes and Tracy, 1993 ) and derived transgenic or edited plants were grown in 15 m 2 growth chambers that fulfil the French S2 safety standards for the culture of transgenic plants ( Gilles et al., 2021 ). The photoperiod consisted of 16 h light and 8 h darkness in a 24 h diurnal cycle.…”

Loss-of-function alleles of ZmPLD3 cause haploid induction in maize

“…Given the conservation of MTL/ZmPLA1/NLD in cereals, knockout of MTL/ZmPLA1/NLD orthologues in rice 12 and wheat 13 also triggered HI. It has been shown that MTL/ZmPLA1/NLD , encoded a pollen-specific patatin-like phospholipase A expressing specifically in vegetative cell but not sperm cell 14 . Further analysis of subcellular localization revealed that MTL/ZmPLA1/NLD targeted the endo-plasma membrane, a specific membrane derived from vegetative cell that surrounds the two sperm cells in pollen 14 – 16 .…”

“…It has been shown that MTL/ZmPLA1/NLD , encoded a pollen-specific patatin-like phospholipase A expressing specifically in vegetative cell but not sperm cell 14 . Further analysis of subcellular localization revealed that MTL/ZmPLA1/NLD targeted the endo-plasma membrane, a specific membrane derived from vegetative cell that surrounds the two sperm cells in pollen 14 – 16 . These results implied that phospholipases highly expressed in pollen might play an important role in sexual reproduction.…”