Cell Surface Expansion in Polarly Growing Root Hairs of<i>Medicago truncatula</i>

Shaw, Sidney L.; Dumais, Jacques; Long, Sharon R.

doi:10.1104/pp.124.3.959

Cited by 94 publications

(71 citation statements)

References 30 publications

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“…A targeted secretion could have the effect of locally weakening the cell wall and allowing turgor-driven cell expansion. In this regard it is pertinent that studies of root hairs, which like the pollen tubes grow by tip expansion, show that the region of maximal shape change at the cell surface is an annular ring, 2 mm to the outside of the polar axis (Shaw et al, 2000). In the pollen tube we suggest that when the fringe is destroyed with Lat-B, vesicles are no longer precisely targeted but randomly dock across the apical domain.…”

Section: Discussionmentioning

confidence: 86%

Pollen Tube Growth Oscillations and Intracellular Calcium Levels Are Reversibly Modulated by Actin Polymerization

Cárdenas¹,

Lovy²,

Kunkel³

et al. 2008

Plant Physiol.

169

137

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Prevention of actin polymerization with low concentrations of latrunculin B (Lat-B; 2 nM) exerts a profound inhibitory effect on pollen tube growth. Using flow-through chambers, we show that growth retardation starts after 10 min treatment with 2 nM Lat-B, and by 15 to 20 min reaches a basal rate of 0.1 to 0.2 mm/s, during which the pollen tube exhibits relatively few oscillations. If treated for 30 min, complete stoppage of growth can occur. Studies on the intracellular Ca 21 concentration indicate that the tipfocused gradient declines in parallel with the inhibition of growth. Tubes exhibiting nonoscillating growth display a similarly reduced and nonoscillating Ca 21 gradient. Studies on the pH gradient indicate that Lat-B eliminates the acidic domain at the extreme apex, and causes the alkaline band to move more closely to the tip. Removing Lat-B and returning the cells to control medium reverses these effects. Phalloidin staining of F-actin reveals that 2 nM Lat-B degrades the cortical fringe; it also disorganizes the microfilaments in the shank causing the longitudinally oriented elements to be disposed in swirls. Cytoplasmic streaming continues under these conditions, however the clear zone is obliterated with all organelles moving into and through the extreme apex of the tube. We suggest that actin polymerization promotes pollen tube growth through extension of the cortical actin fringe, which serves as a track to target cell wall vesicles to preferred exocytotic sites on the plasma membrane.

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Section: Discussionmentioning

confidence: 86%

Pollen Tube Growth Oscillations and Intracellular Calcium Levels Are Reversibly Modulated by Actin Polymerization

Cárdenas¹,

Lovy²,

Kunkel³

et al. 2008

Plant Physiol.

169

137

View full text Add to dashboard Cite

show abstract

“…Approximately the first third of root hair growth may be non-pulsatile and slower than the later pulsatile phase (Wymer et al, 1997), yet in another species, growth was reportedly non-pulsatile throughout hair elongation (Shaw et al, 2000). Thus, again pulsatile growth is apparently neither obligatory nor common in this tip-growing cell type.…”

Section: Absence Of Pulsatile Growthmentioning

confidence: 92%

Time series analysis demonstrates the absence of pulsatile hyphal growth

2003

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Hyphal tip growth has been previously reported as pulsatile, defined as regularly alternating fast and slow rates of extension. The growth of pollen tubes, and hyphae of Neurospora crassa and Saprolegnia ferax were analysed using high spatial and temporal resolution. By using long (100-500 s) records of growth rate, sampled every second, it was possible to apply rigorous statistical analysis of the time series. As previously demonstrated, pollen tubes can show pulsatile growth, detectable with this system. In contrast, hyphal growth rates do not show any evidence of pulsatile growth; instead, growth rates appear to fluctuate randomly. It is concluded that pulsatile growth is not a common feature of hyphal tip growth.

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“…However, the PME data in tobacco challenge this view by showing that the inverted cone stains much less brightly than the flanks surrounding the cone ; data herein). It is possible that material moves forward along the edge of the cell, being directed by the cortical actin fringe (Lovy-Wheeler et al, 2005), and deposits as an annulus outside of the polar axis (Bove et al, 2008;Zonia and Munnik, 2008), as has been shown for root hairs (Shaw et al, 2000;Dumais et al, 2004). This is an attractive idea, but more work is needed to establish its occurrence in pollen tubes.…”

Section: Exocytosis Has Been Studied In Other Pollen Tubesmentioning

confidence: 98%

Exocytosis Precedes and Predicts the Increase in Growth in Oscillating Pollen Tubes

et al. 2009

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We examined exocytosis during oscillatory growth in lily (Lilium formosanum and Lilium longiflorum) and tobacco (Nicotiana tabacum) pollen tubes using three markers: (1) changes in cell wall thickness by Nomarski differential interference contrast (DIC), (2) changes in apical cell wall fluorescence in cells stained with propidium iodide (PI), and (3) changes in apical wall fluorescence in cells expressing tobacco pectin methyl esterase fused to green fluorescent protein (PME-GFP). Using PI fluorescence, we quantified oscillatory changes in the amount of wall material from both lily and tobacco pollen tubes. Measurement of wall thickness by DIC was only possible with lily due to limitations of microscope resolution. PME-GFP, a direct marker for exocytosis, only provides information in tobacco because its expression in lily causes growth inhibition and cell death. We show that exocytosis in pollen tubes oscillates and leads the increase in growth rate; the mean phase difference between exocytosis and growth is -988 6 38 in lily and -1248 6 48 in tobacco. Statistical analyses reveal that the anticipatory increase in wall material predicts, to a high degree, the rate and extent of the subsequent growth surge. Exocytosis emerges as a prime candidate for the initiation and regulation of oscillatory pollen tube growth.

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Cell Surface Expansion in Polarly Growing Root Hairs ofMedicago truncatula

Cited by 94 publications

References 30 publications

Pollen Tube Growth Oscillations and Intracellular Calcium Levels Are Reversibly Modulated by Actin Polymerization

Pollen Tube Growth Oscillations and Intracellular Calcium Levels Are Reversibly Modulated by Actin Polymerization

Time series analysis demonstrates the absence of pulsatile hyphal growth

Exocytosis Precedes and Predicts the Increase in Growth in Oscillating Pollen Tubes

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