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Title: Deficiencies in cluster‐2 ALA lipid flippases result in salicylic acid‐dependent growth reductions
Abstract P4 ATPases (i.e., lipid flippases) are eukaryotic enzymes that transport lipids across membrane bilayers. In plants, P4 ATPases are named Aminophospholipid ATPases (ALAs) and are organized into five phylogenetic clusters. Here we generated an Arabidopsis mutant lacking all five cluster‐2 ALAs (ala8/9/10/11/12), which is the most highly expressedALAsubgroup in vegetative tissues. Plants harboring the quintuple knockout (KO) show rosettes that are 2.2‐fold smaller and display chlorotic lesions. A similar but less severe phenotype was observed in anala10/11double KO. The growth and lesion phenotypes ofala8/9/10/11/12mutants were reversed by expressing aNahGtransgene, which encodes an enzyme that degrades salicylic acid (SA). A role for SA in promoting the lesion phenotype was further supported by quantitative PCR assays showing increased mRNA abundance for an SA‐biosynthesis geneISOCHORISMATE SYNTHASE 1(ICS1) and two SA‐responsive genesPATHOGENESIS‐RELATED GENE 1(PR1) andPR2.Lesion phenotypes were also reversed by growing plants in liquid media containing either low calcium (~0.1 mM) or high nitrogen concentrations (~24 mM), which are conditions known to suppress SA‐dependent autoimmunity. Yeast‐based fluorescent lipid uptake assays revealed that ALA10 and ALA11 display overlapping substrate specificities, including the transport of LysoPC signaling lipids. Together, these results establish that the biochemical functions of ALA8–12 are at least partially overlapping, and that deficiencies in cluster‐2 ALAs result in an SA‐dependent autoimmunity phenotype that has not been observed for flippase mutants with deficiencies in otherALAclusters.  more » « less
Award ID(s):
2129234
PAR ID:
10511679
Author(s) / Creator(s):
; ; ; ; ; ; ;
Publisher / Repository:
Physiologia Plantarum
Date Published:
Journal Name:
Physiologia Plantarum
Volume:
176
Issue:
2
ISSN:
0031-9317
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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