Calcium Channel Activity during Pollen Tube Growth and Reorientation.

Malhó, Rui; Read, Nick D.; Trewavas, Anthony; Pais, M. S.

doi:10.1105/tpc.7.8.1173

Cited by 185 publications

(144 citation statements)

References 22 publications

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“…Wu, unpublished data). The stretch-activated PM Ca 21 channels have been proposed to be present in pollen and pollen tubes and may function in pollen germination and tube growth (Pierson et al, 1994;Malhó et al, 1995;Malhó and Trewavas, 1996). The features of the stretch-activated Ca 21 channels differ from those of the hyperpolarization-activated Ca 21 channels in pollen and pollen tubes reported in this study.…”

Section: Identification Of Ca 21 Channels In Arabidopsis Pollen Protocontrasting

confidence: 53%

“…These two organic Ca 21 channel blockers are commonly used to block animal Ca 21 channels (Hess, 1990). The findings of this study and of Malhó et al (1995) suggest that different types of Ca 21 channels may exist in pollen and pollen tubes from those in animal cells. In addition, we observed another type of Ca 21 channel, which was stretchactivated and Gd 31 -or La 31 -sensitive, in Arabidopsis and Brassica pollen protoplasts (Y.F.…”

Section: Identification Of Ca 21 Channels In Arabidopsis Pollen Protomentioning

confidence: 72%

“…Several lines of evidence suggest that PM Ca 21 channels may be prominently involved in the regulation of this Ca 21 gradient (Pierson et al, 1994(Pierson et al, , 1996Malhó et al, 1995). Ca 21 influx in pollen or pollen tubes has been investigated by using 45 Ca 21 (Jaffe et al, 1975), Ca 21 -selective vibrating probes (Kuhtreiber and Jaffe, 1990;Pierson et al, 1994;Holdaway-Clarke et al, 1997;Messerli et al, 1999;Franklin-Tong et al, 2002), and Mn 21 -quenching techniques .…”

Section: Discussionmentioning

confidence: 99%

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Ca2+-Permeable Channels in the Plasma Membrane of Arabidopsis Pollen Are Regulated by Actin Microfilaments

et al. 2004

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Cytosolic free Ca 21 and actin microfilaments play crucial roles in regulation of pollen germination and tube growth. The focus of this study is to test the hypothesis that Ca 21 channels, as well as channel-mediated Ca 21 influxes across the plasma membrane (PM) of pollen and pollen tubes, are regulated by actin microfilaments and that cytoplasmic Ca 21 in pollen and pollen tubes is consequently regulated. In vitro Arabidopsis (Arabidopsis thaliana) pollen germination and tube growth were significantly inhibited by Ca 21 channel blockers La 31 or Gd 31 and F-actin depolymerization regents. The inhibitory effect of cytochalasin D (CD) or cytochalasin B (CB) on pollen germination and tube growth was enhanced by increasing external Ca 21 . Ca 21 fluorescence imaging showed that addition of actin depolymerization reagents significantly increased cytoplasmic Ca 21 levels in pollen protoplasts and pollen tubes, and that cytoplasmic Ca 21 increase induced by CD or CB was abolished by addition of Ca 21 channel blockers. By using patch-clamp techniques, we identified the hyperpolarization-activated inward Ca 21 currents across the PM of Arabidopsis pollen protoplasts. The activity of Ca 21 -permeable channels was stimulated by CB or CD, but not by phalloidin. However, preincubation of the pollen protoplasts with phalloidin abolished the effects of CD or CB on the channel activity. The presented results demonstrate that the Ca 21 -permeable channels exist in Arabidopsis pollen and pollen tube PMs, and that dynamic actin microfilaments regulate Ca 21 channel activity and may consequently regulate cytoplasmic Ca 21 .The primary function of pollen and pollen tubes is to deliver sperms to egg apparatus for double fertilization that is required for sexual reproduction of flowering plants. Pollen germination and pollen tube growth are a continuous and highly polarized process characteristic of tip growth; thus pollen and pollen tubes provide an ideal model system for the study of cell polarity control and tip growth. It is well known that extracellular Ca 21 is required for pollen germination and tube growth (for review, see Steer and Steer, 1989;Taylor and Hepler, 1997;Malhó , 1998;Franklin-Tong, 1999), which indicates a possible involvement of Ca 21 influx in pollen germination and tube growth. Upon pollen hydration and germination, cytoplasmic Ca 21 concentration ([Ca 21 ] i ) at the germinal aperture where the pollen tube emerges increases to a higher level than other regions, and a tip-focused Ca 21 gradient is then established and sustained while a pollen tube grows forward (Rathore et al., 1991;Pierson et al., 1994;Feijó et al., 1995). Disruption or modification of the Ca 21 gradient inhibits pollen tube growth (Miller et al., 1992) or changes its growth direction (Malhó and Trewavas, 1996). The tip-focused Ca 21 gradient oscillates in the pollen tubes of lily (Lilium longiflorum) and other species (Holdaway-Clarke et al., 1997;Messerli and Robinson, 1997;Messerli et al., 2000). Ca 21 mobilization from intracellular Ca...

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Section: Identification Of Ca 21 Channels In Arabidopsis Pollen Protocontrasting

confidence: 53%

Section: Identification Of Ca 21 Channels In Arabidopsis Pollen Protomentioning

confidence: 72%

Section: Discussionmentioning

confidence: 99%

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Ca2+-Permeable Channels in the Plasma Membrane of Arabidopsis Pollen Are Regulated by Actin Microfilaments

et al. 2004

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“…S4 D and E). We tested this prediction by treating pollen tubes with LaCl 3 , a calcium channel blocker that has been shown to lower cytosolic calcium levels in pollen tubes (32). When treated with 10 M LaCl 3 , the pollen tubes maintained a high level of apical ROP1 activity (Ͼ 1.5) but lost its oscillation (Fig.…”

Section: Simulation and Experimental Validation Of The Effect Of Calcmentioning

confidence: 99%

Calcium participates in feedback regulation of the oscillating ROP1 Rho GTPase in pollen tubes

Yang

2009

Proc. Natl. Acad. Sci. U.S.A.

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Biological oscillation occurs at various levels, from cellular signaling to organismal behaviors. Mathematical modeling has allowed a quantitative understanding of slow oscillators requiring changes in gene expression (e.g., circadian rhythms), but few theoretical studies have focused on the rapid oscillation of cellular signaling. The tobacco pollen tube, which exhibits growth bursts every 80 s or so, is an excellent system for investigating signaling oscillation. Pollen tube growth is controlled by a tip-localized ROP1 GTPase, whose activity oscillates in a phase about 90 degrees ahead of growth. We constructed a mathematical model of ROP1 activity oscillation consisting of interlinking positive and negative feedback loops involving F-actin and calcium, ROP1-signaling targets that oscillate in a phase about 20 degrees and 110 degrees behind ROP1 activity, respectively. The model simulates the observed changes in ROP1 activity caused by F-actin disruption and predicts a role for calcium in the negative feedback regulation of the ROP1 activity. Our experimental data strongly support this role of calcium in tip growth. Thus, our findings provide insight into the mechanism of pollen tube growth and the oscillation of cellular signaling.model ͉ ROP1 GTPase ͉ tip growth

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“…[1][2][3] Early studies were focus on the plasma membrane calcium channel regulation and cytosolic free calcium concentration variation in the pollen tube reason by which was one of the most important second messengers in plants. [3][4][5][6][7] However, reports have also showed that the potassium channels in the pollen tubes were also involved in several important steps of plant sexual reproduction. [8][9][10][11][12][13][14][15][16][17][18][19] Recently, more reports further demonstrated this phenomena.…”

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confidence: 99%