Activation of Phospholipases C and D Is an Early Response to a Cold Exposure in Arabidopsis Suspension Cells

Abstract

The signaling events generated by a cold exposure are poorly known in plants. We were interested in checking the possible activation of enzymes of the phosphoinositide signaling pathway in response to a temperature drop. In Arabidopsis suspension cells labeled with 33 PO 4 3Ϫ , a cold treatment induces a rapid increase of phosphatidic acid (PtdOH) content. This production was due to the simultaneous activation of phospholipase C (through diacylglycerol kinase activity) and phospholipase D, as monitored by the production of inositol triphosphate and of transphosphatidylation product, respectively. Moreover, inhibitors of the phosphoinositide pathway and of diacylglycerol kinase reduced PtdOH production. Enzyme activation occurred immediately after cells were transferred to low temperature. The respective contribution of both kind of phospholipases in cold-induced production of PtdOH could be estimated. We created conditions where phospholipids were labeled with 33 PO 4 3Ϫ , but with ATP being nonradioactive. In such conditions, the apparition of radioactive PtdOH reflected PLD activity. Thus, we demonstrated that during a cold stress, phospholipase D activity accounted for 20% of PtdOH production. The analysis of composition in fatty acids of cold-produced PtdOH compared with that of different phospholipids confirmed that cold-induced PtdOH more likely derived mainly from phosphoinositides. The addition of chemical reagents modifying calcium availability inhibited the formation of PtdOH, showing that the cold-induced activation of phospholipase pathways is dependent on a calcium entry.During their development, plants are submitted to various stresses, either abiotic ones like changes in light intensities, in temperature conditions, or in soil water potential, or biotic ones like interactions with microorganisms. Among these stresses, changes in temperature are very important for plants cultivated in temperate climates. They are submitted to temperature variations between day and night, but also over the different seasons. Contrary to mammals, no system to maintain temperature homeostasis exists in plants that are going to adapt to a temperature change by modifying their metabolism. It has been observed for instance that in response to a cold treatment, specific genes are expressed such as those leading to the accumulation of sugar and Pro. Most of these metabolic changes explain why some plants submitted for a while to nonchilling, cold temperatures can resist to subzero temperature thanks to the so called cold-acclimation phenomenon (Thomashow, 1998(Thomashow, , 2001. Although many genes have been shown to be induced by a cold treatment (Seki et al., 2001), the signaling pathway implicated in the perception and in the transduction of cold signal into the cells is poorly known. In Synechocystis sp., Vigh and his collaborators (Vigh et al., 1993) proposed that rigidification of the plasma membrane might be the event that initiates all the downstream signaling cascade. Suzuki and collaborators (Suzuki et al., 20...

Desaturase mutants reveal that membrane rigidification acts as a cold perception mechanism upstream of the diacylglycerol kinase pathway in Arabidopsis cells

“…To discriminate between these different sources we applied a protocol of differential labeling with radioactive orthophosphate [7]. WT cells were labeled with [ 33 P]-orthophosphate for 15 min (Fig.…”

Effect of n-butanol and cold pretreatment on the cytoskeleton and the ultrastructure of maize microspores when cultured in vitro

“…It is proven that activity of phospholipase D increased after cold exposure (Ruelland et al 2002), leading to the elevation of intracellular PA levels. In Arabidopsis, phosphatidic acid negatively affected the actin-binding ability of a heterodimeric capping protein (CP) that binds actin filaments at the barbed ends (Huang et al 2006;Pleskot et al 2012).…”

AtDGK2, a Novel Diacylglycerol Kinase from Arabidopsis thaliana, Phosphorylates 1-Stearoyl-2-arachidonoyl-sn-glycerol and 1,2-Dioleoyl-sn-glycerol and Exhibits Cold-inducible Gene Expression

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