Article Figures & Data
Figures
- Figure 1.
Changes in the apical cell volume of pollen tubes in response to osmotic perturbation. Each value is the mean of 50 pollen tubes ± se. The region analyzed spans the apical 50-μm length of the pollen tubes. Hypo-osmotic stress is induced by the addition of water and causes cell swelling. Hyperosmotic stress is induced by the addition of NaCl and causes cell shrinking.
- Figure 2.
Identification of phospholipids during pollen tube growth. 32Pi was added to pollen tube cultures, and lipids were extracted at the times indicated and analyzed by TLC using an alkaline solvent system. Lane 1, 15 min. Lane 2, 30 min. Lane 3, 1 h. Lane 4, 2 h. Lane 5, 4 h. Lane 6, Phospholipid marker standard.
- Figure 3.
Rate of incorporation of 32Pi into pollen tube phospholipids. Data are expressed as percentage of 32Pi incorporated into each phospholipid with respect to total 32Pi incorporated into all phospholipids at each time point. Phospholipids with high turnover rates have high initial rates of 32Pi incorporation, whereas structural phospholipids have higher incorporation of 32Pi after an initial time lag. A, PI(3,5)P2. B, PI(4,5)P2. C, PIP. D, PA. E, PI. F, PC. G, PE. H, PG.
- Figure 4.
Analysis of PLD activity during pollen tube growth. A, Lipids were extracted and analyzed by TLC using an ethyl acetate solvent system. Lane 1, Control in the absence of n-butanol. Lanes 2 to 5, 5, 15, 30, and 60 min after the addition of 0.1% (v/v) n-butanol. B, Increasing accumulation of PA and PBut during pollen tube growth indicates constitutive activity of PLD. PBut values are expressed as percentage increase with respect to the 5-min sample.
- Figure 5.
Hypo-osmotic stress stimulates PLD activity and generates increased levels of PA. Lipids were extracted and analyzed by TLC using an ethyl acetate solvent system. A, Lane 1, control in the absence of n-butanol. Lanes 2 and 3, 5 and 10 min after the addition of 25% (v/v) water. Lanes 4 and 5, 5 and 10 min after the addition of 50% (v/v) water. Lanes 6 and 7, 5 and 10 min after the addition of 100% (v/v) water. B, Concentration-dependent increases in PA and PBut with increasing hypo-osmotic stress (percentage water, v/v). All samples analyzed at 10 min after the start of hypo-osmotic stress.
- Figure 6.
Time-dependent increases in PA and PBut after hypo-osmotic treatment of 100% (v/v) water. Values represent percentage increase of PA compared with untreated control and PBut compared with 10-min sample. A, time course of PA increase. B, Time course of PBut increase.
- Figure 7.
Hypo-osmotic stress induces a decrease in PIP. Lipids were extracted and analyzed by TLC using an alkaline solvent system. A, Concentration-dependent decrease in PIP. Lane 1, Control. Lanes 2 and 3, 5 and 10 min after the addition of 25% (v/v) water. Lanes 4 and 5, 5 and 10 min after the addition of 50% (v/v) water. Lanes 6 and 7, 5 and 10 min after the addition of 100% (v/v) water. B, Time-dependent decrease in PIP. Lane 1, Control. Lanes 2 to 8, 30 s, 1 min, 2 min, 4 min, 8 min, 15 min, and 30 min after the addition of 100% (v/v) water. C, Time course of PIP decrease after addition of 100% (v/v) water.
- Figure 8.
Hyperosmotic stress inhibits PLD activity and reduces the level of PA. Lipids were extracted and analyzed by TLC using an ethyl acetate solvent system. Lanes 1 and 2, Control 0 and 10 min after the addition of 0.1% (v/v) n-butanol. Lanes 3 and 4, 15 and 30 min after the addition of 50 mm NaCl. Lanes 5 and 6, 15 and 30 min after the addition of 100 mm NaCl. Lanes 7 and 8, 15 and 30 min after the addition of 200 mm NaCl. Lanes 9 and 10, 15 and 30 min after the addition of 400 mm NaCl. All hyperosmotic stress tests (lanes 3–10) performed in the presence of 0.1% (v/v) n-butanol. B, Time-dependent decrease in PA at 200 and 400 mm NaCl.
- Figure 9.
Hyperosmotic stress induces increases in PI(3,5)P2 and PI(4,5)P2. A, Concentration-dependent increases in PI(3,5)P2 and PI(4,5)P2 at 30 min after the start of treatment. Controls, Untreated pollen tubes. B, Time-dependent increases in PI(3,5)P2 and PI(4,5)P2 after addition of 400 mm NaCl. Lipids were extracted and analyzed by TLC using an alkaline solvent system. Lane 1, Control, untreated pollen tubes. Lanes 2 to 8, 30 s, 1 min, 2 min, 4 min, 8 min, 15 min, and 30 min after addition of 400 mm NaCl. Lane 9, Phospholipid marker standard. C, Analysis of time-dependent increases in PI(3,5)P2 and PI(4,5)P2 induced by 400 mm NaCl. Controls, untreated pollen tubes.
