Wimalasekera R., Pejchar P., Holk A., Martinec J., Scherer G.F.E.
MOLECULAR PLANT
3:
610-625,
2010
Keywords:
Auxin, brassinolide signaling, phosphate deficiency, phosphatidylcholinesplitting phospholipase C (PC-PLC), NPC genes
Abstract:
Phosphatidylcholine-hydrolysing phospholipase C (PC-PLC) catalyzes the hydrolysis of
phosphatidylcholine (PC) to generate phosphocholine and diacylglycerol (DAG). PC-PLC has
a long tradition in animal signal transduction to generate DAG as a second messenger besides
the classical phosphatidylinositol splitting phospholipase C (PI-PLC). Based on amino acid
sequence similarity to bacterial PC-PLC, six putative PC-PLC genes (NPC1 to NPC6) were
identified in the Arabidopsis genome. RT-PCR analysis revealed overlapping expression
pattern of NPC genes in root, stem, leaf, flower and silique. In auxin-treated PNPC3:GUS and
PNPC4:GUS seedlings strong increase of GUS activity was visible in roots, leaves and shoots
and to a weaker extent, in brassinolide-treated (BL) seedlings. PNPC4:GUS seedlings also
responded to cytokinin with increased GUS activity in young leaves. Compared to wild type,
T-DNA insertional knockouts npc3 and npc4 showed shorter primary roots and lower lateral
root density at low BL concentrations but increased lateral root densities in response to
exogenous 0.05-1.0 μM BL. BL-induced expression of TCH4 and LRX2 which are involved
in cell expansion was impaired but not impaired in repression of CPD, a BL biosynthesis
gene, in BL-treated npc3 and npc4. These observations suggest NPC3 and NPC4 are
important in BL-mediated signaling in root growth. When treated with 0.1 μM BL, DAG
accumulation was observed in tobacco BY-2 cell cultures labelled with fluorescent PC as
early as 15 min after application. We hypothesize that at least one PC-PLC is a plant signaling
enzyme in BL signal transduction and, as shown earlier, in elicitor signal transduction.
Fulltext: contact IEB authors
IEB authors: Jan Martinec,
Přemysl Pejchar
Čeština
English