Figure S2.
Schematic describing the organization of actin filaments and distribution of vesicles in WT, adf7, and adf10 pollen tubes. (A) Loss of function of ADF7 and ADF10 has differential effects on the recovery pattern of the backward movement of vesicles in pollen tubes. The left column shows prebleached pollen tubes. Yellow boxes indicate the photobleached regions. The right panels show the time-lapse images of pollen tubes after photobleaching. The signals within the unbleached tip region initially decrease after bleaching due to the backward movement of unbleached vesicles, and the signals then recover after the tipward movement of fluorescent vesicles. Insets show the full view of the distribution of RabA4b vesicles lingering in the tip before the fluorescence signals of the unbleached apex region reach a minimum. The V-shaped accumulation pattern of RabA4b vesicles can be distinguished at the very early stage of recovery. The accumulation of RabA4b mainly occurred at the very tip of the WT pollen tubes. By comparison, vesicles accumulated in a region a bit further away from the very tip of the adf7 pollen tube, and vesicles accumulated within a much wider apical region in adf10 pollen tubes. The brightness of all images was adjusted intentionally for optimal presentation. Bars = 5 μm. (B) The left panels show the organization of actin filaments and overall distribution of vesicles in WT, adf7, and adf10 pollen tubes. The right panels, within the dashed blue box, show the postulated process of vesicle delivery and eventual accumulation of vesicles at the tip of WT, adf7, and adf10 pollen tubes. Transport vesicles are delivered to the tip of WT pollen tubes using apical actin filaments at the cortex as tracks. Vesicles are released after reaching the tip. This tip-directed vesicle transportation is differentially impaired in adf7 and adf10 pollen tubes because of differential disorganization of apical actin filaments at the cortex. In WT pollen tubes, transport vesicles are released and accumulate in the region with fewer actin filaments, which is indicated by the dashed white circle in the left panel. In adf7 pollen tubes, fewer vesicles accumulate within the corresponding region because the amount of actin filaments is increased. In WT pollen tubes, the released vesicles are physically restricted by the inner apical actin filaments that naturally assume an inverted V cone-shaped distribution (Qu et al., 2017). In adf10 pollen tubes, the region of vesicle accumulation is enlarged because the disorganized inner apical actin filaments are defective in spatially restricting the vesicles. By comparison, the pattern of apical vesicle accumulation in adf7 pollen tubes is similar to that in WT, as the organization of inner apical actin filaments appears quite similar to that in WT. Green and red arrows indicate the direction of tip-directed and backward movement of vesicles, respectively. The green dashed lines in the left panel indicate the border of vesicle accumulation.

Schematic describing the organization of actin filaments and distribution of vesicles in WT, adf7, and adf10 pollen tubes. (A) Loss of function of ADF7 and ADF10 has differential effects on the recovery pattern of the backward movement of vesicles in pollen tubes. The left column shows prebleached pollen tubes. Yellow boxes indicate the photobleached regions. The right panels show the time-lapse images of pollen tubes after photobleaching. The signals within the unbleached tip region initially decrease after bleaching due to the backward movement of unbleached vesicles, and the signals then recover after the tipward movement of fluorescent vesicles. Insets show the full view of the distribution of RabA4b vesicles lingering in the tip before the fluorescence signals of the unbleached apex region reach a minimum. The V-shaped accumulation pattern of RabA4b vesicles can be distinguished at the very early stage of recovery. The accumulation of RabA4b mainly occurred at the very tip of the WT pollen tubes. By comparison, vesicles accumulated in a region a bit further away from the very tip of the adf7 pollen tube, and vesicles accumulated within a much wider apical region in adf10 pollen tubes. The brightness of all images was adjusted intentionally for optimal presentation. Bars = 5 μm. (B) The left panels show the organization of actin filaments and overall distribution of vesicles in WT, adf7, and adf10 pollen tubes. The right panels, within the dashed blue box, show the postulated process of vesicle delivery and eventual accumulation of vesicles at the tip of WT, adf7, and adf10 pollen tubes. Transport vesicles are delivered to the tip of WT pollen tubes using apical actin filaments at the cortex as tracks. Vesicles are released after reaching the tip. This tip-directed vesicle transportation is differentially impaired in adf7 and adf10 pollen tubes because of differential disorganization of apical actin filaments at the cortex. In WT pollen tubes, transport vesicles are released and accumulate in the region with fewer actin filaments, which is indicated by the dashed white circle in the left panel. In adf7 pollen tubes, fewer vesicles accumulate within the corresponding region because the amount of actin filaments is increased. In WT pollen tubes, the released vesicles are physically restricted by the inner apical actin filaments that naturally assume an inverted V cone-shaped distribution (Qu et al., 2017). In adf10 pollen tubes, the region of vesicle accumulation is enlarged because the disorganized inner apical actin filaments are defective in spatially restricting the vesicles. By comparison, the pattern of apical vesicle accumulation in adf7 pollen tubes is similar to that in WT, as the organization of inner apical actin filaments appears quite similar to that in WT. Green and red arrows indicate the direction of tip-directed and backward movement of vesicles, respectively. The green dashed lines in the left panel indicate the border of vesicle accumulation.

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