Figure 1.
Figure 1. Subcellular localization of YFP-RabA4d in growing pollen tubes. (A and B) Representative confocal images of tobacco pollen tubes transiently expressing YFP-RabA4d (A) or GFP as a control (B). Shown are single laser sections focused on the midplane of pollen tubes. (C) A representative confocal image of a YFP-Rab4d–expressing tube treated with BFA. 3 h after bombardment, transformed tubes were treated with 1 μg/ml BFA for 1 h before imaging. Shown are single laser sections focused on the midplane of pollen tubes. (D) A time series of a tube showing the dynamics and oscillation of the tip localization of YFP-RabA4d. Confocal images were selected from the entire time series (5-s intervals) of a growing tube expressing YFP-RabA4d. The numbers beneath each image indicate time elapsed from the beginning of the time series. Shown are single laser sections focused on the midplane. Images for this time series are from Video 1 (available). (E) A representative median focal plane image of tobacco pollen tube expressing YFP-RabA4d. The mean intensity of the YFP signal was measured in the area within 5 μm from the tip (circle). Bars, 10 μm. (F) Quantitative analysis of the YFP-RabA4d accumulation to the tip and growth rate oscillation. 4 h after bombardment, time-lapse confocal images of pollen tips were collected at 5-s intervals. YFP signal intensity within 5 μm from the tip shown in E of YFP signal (left) was compared with tip elongation rate (right). Similar results were obtained from five individual experiments. Note the mean oscillation period of tip accumulation of YFP-RabA4d was ∼68 s. Break is inserted for focus adjustment and reposition of the pollen tube. (G) Cross correlation analysis of F. To quantify the phase relationship between vesicle accumulation and tip growth, the growth curve was shifted with respect to the YFP-RabA4d curve, and the values of the correlation coefficient corresponding to a phase shift were measured. The highest correlation occurs when growth oscillation lags the oscillation of YFP signal by 10 s, which indicates that the growth burst follows YFP-RabA4d accumulation at the tip.

Subcellular localization of YFP-RabA4d in growing pollen tubes. (A and B) Representative confocal images of tobacco pollen tubes transiently expressing YFP-RabA4d (A) or GFP as a control (B). Shown are single laser sections focused on the midplane of pollen tubes. (C) A representative confocal image of a YFP-Rab4d–expressing tube treated with BFA. 3 h after bombardment, transformed tubes were treated with 1 μg/ml BFA for 1 h before imaging. Shown are single laser sections focused on the midplane of pollen tubes. (D) A time series of a tube showing the dynamics and oscillation of the tip localization of YFP-RabA4d. Confocal images were selected from the entire time series (5-s intervals) of a growing tube expressing YFP-RabA4d. The numbers beneath each image indicate time elapsed from the beginning of the time series. Shown are single laser sections focused on the midplane. Images for this time series are from Video 1 . (E) A representative median focal plane image of tobacco pollen tube expressing YFP-RabA4d. The mean intensity of the YFP signal was measured in the area within 5 μm from the tip (circle). Bars, 10 μm. (F) Quantitative analysis of the YFP-RabA4d accumulation to the tip and growth rate oscillation. 4 h after bombardment, time-lapse confocal images of pollen tips were collected at 5-s intervals. YFP signal intensity within 5 μm from the tip shown in E of YFP signal (left) was compared with tip elongation rate (right). Similar results were obtained from five individual experiments. Note the mean oscillation period of tip accumulation of YFP-RabA4d was ∼68 s. Break is inserted for focus adjustment and reposition of the pollen tube. (G) Cross correlation analysis of F. To quantify the phase relationship between vesicle accumulation and tip growth, the growth curve was shifted with respect to the YFP-RabA4d curve, and the values of the correlation coefficient corresponding to a phase shift were measured. The highest correlation occurs when growth oscillation lags the oscillation of YFP signal by 10 s, which indicates that the growth burst follows YFP-RabA4d accumulation at the tip.

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