Roles of Arabidopsis patatin-related phospholipases a in root development are related to auxin responses and phosphate deficiency.
Phospholipase A enzymes cleave phospho- and galactolipids to generate free fatty acids and lysolipids that function in animal and plant hormone signaling. Here, we describe three Arabidopsis patatin-related phospholipase A (pPLA) genes AtPLAIVA, AtPLAIVB, and AtPLAIVC and their corresponding proteins. Loss-of-function mutants reveal roles for these pPLAs in roots during normal development and under phosphate deprivation. AtPLAIVA is expressed strongly and exclusively in roots and AtplaIVA-null mutants have reduced lateral root development, characteristic of an impaired auxin response. By contrast, AtPLAIVB is expressed weakly in roots, cotyledons, and leaves but is transcriptionally induced by auxin, although AtplaIVB mutants develop normally. AtPLAIVC is expressed in the floral gynaecium and is induced by abscisic acid (ABA) or phosphate deficiency in roots. While an AtplaIVC-1 loss-of-function mutant displays ABA responsiveness, it exhibits an impaired response to phosphate deficiency during root development. Recombinant AtPLA proteins hydrolyze preferentially galactolipids and, less efficiently, phospholipids, although these enzymes are not localized in chloroplasts. We find that AtPLAIVA and AtPLAIVB are phosphorylated by calcium-dependent protein kinases in vitro and this enhances their activities on phosphatidylcholine but not on phosphatidylglycerol. Taken together, the data reveal novel functions of pPLAs in root development with individual roles at the interface between phosphate deficiency and auxin signaling.
Rietz
Steffen
S
Max Planck Institute for Plant Breeding Research, Department of Plant Microbe Interactions, Carl von Linné Weg 10, D-50829 Cologne, Germany.
Dermendjiev
Georgi
G
Oppermann
Esther
E
Tafesse
Fikadu Getah
FG
Effendi
Yunus
Y
Holk
André
A
Parker
Jane E
JE
Teige
Markus
M
Scherer
Günther F E
GF
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism*; D008969:Molecular Sequence Data; D010710:Phosphates / Q000172:deficiency / Q000378:metabolism; D010741:Phospholipases A / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D018517:Plant Roots / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D010710:Phosphates; D010741:Phospholipases A