The Lipid Flippases ALA4 and ALA5 Play Critical Roles in Cell Expansion and Plant Growth

Abstract

A subclass of lipid flippases contribute to glycerolipid and sphingolipid homeostasis in Arabidopsis leaves, and play critical roles in cell expansion and vegetative growth. Footnotes: Author contributions: J.D. authored the manuscript. R.P. and J.D. analyzed vegetative physiology. S.M. bred the double-knockout lines and identified dwarf mutants. E.B., A.R., and J.S. performed subcellular localization experiments. L.P. and R.L. were involved in the cloning of ALA5 for yeast expression. T.B. performed lipid uptake and functional complementation assays. R.L. analyzed the data and carried out statistical analysis for yeast experiments. M.P. and R.L. supervised yeast experiments. E.C. and R.C. performed sphingolipid profiling of ala4/5 mutants. J.H. performed all plant crosses, supervised in planta experiments, and assisted J.D. in writing. J.H. agrees to serve as author responsible for contact.

Mini-review: Lipid flippases as putative targets for biotechnological crop improvement

“…A role in GlcCer signaling was proposed for ALA4 and ALA5, but transport of this lipid could not be confirmed for ALA5, and ALA4 was not tested (Davis et al, 2020).…”

“…Further work showed ALA3-dependent phosphatidylglycerol (PG) transport but failed to detect significant PE and PC translocation ( Jensen et al., 2017 ). ALA5 has a preference for PC, but still recognizes PE to a significant extent in fluorescent lipid-based uptake assays ( Davis et al., 2020 ). In addition, yeast expression of ALA5 results in resistance to low concentrations of the toxic PS-binding peptide papuamide, indicating that the plant protein can also transport natural PS ( Davis et al., 2020 ).…”

“…ALA5 has a preference for PC, but still recognizes PE to a significant extent in fluorescent lipid-based uptake assays ( Davis et al., 2020 ). In addition, yeast expression of ALA5 results in resistance to low concentrations of the toxic PS-binding peptide papuamide, indicating that the plant protein can also transport natural PS ( Davis et al., 2020 ). In the same experiments, ALA5 was shown to transport ceramide-derived sphingomyelin.…”

“…The only confirmed example of a plant flippase involved in lipid signaling is ALA10, which was shown to be required for lysoPC signaling during light-dependent stomatal movement and adaptive responses to phosphate starvation ( Poulsen et al., 2015 ). A role in GlcCer signaling was proposed for ALA4 and ALA5, but transport of this lipid could not be confirmed for ALA5, and ALA4 was not tested ( Davis et al., 2020 ).…”

Arabidopsis P4 ATPase-mediated cell detoxification confers resistance to Fusarium graminearum and Verticillium dahliae

“…In Arabidopsis , there are 12 members (AtALA1 to AtALA12; Arabidopsis thaliana a minophospho l ipid A TPases) in the P4 ATPase family. Although important roles of AtALAs have been reported in tolerance to temperature stresses 67 – 69 , disease resistance 70 – 72 , auxin polar distribution 73 , cell expansion and plant growth 74 , 75 , pollen and ovule development 76 – 78 , little is known about the role of P4 ATPases in mycotoxin detoxification, even though ALA4 was demonstrated to be involved in heavy mental detoxification 79 .…”