Pollen Tubes and Tip Growth: of Biophysics and Tipomics

Obermeyer, Gerhard; Feijó, José A.

doi:10.1007/978-3-319-56645-0_1

Cited by 3 publications

(5 citation statements)

References 30 publications

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“…The lack of correlation between internal turgor pressure and growth rate of pollen tubes 39 (reviewed in refs. 40,41 ) contradicts the assumption that turgor is modulated during oscillatory growth 42,43 . Our results support a tip growth model, which is not dependent on increased turgor pressure, and suggest that the combined fluxes of the opposing circuits of cations and anions at the tip and shank balance each other out, so that there is no net build-up of osmotically relevant ionic concentrations 34 .…”

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confidence: 90%

Plasma membrane H+-ATPases sustain pollen tube growth and fertilization

et al. 2020

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Pollen tubes are highly polarized tip-growing cells that depend on cytosolic pH gradients for signaling and growth. Autoinhibited plasma membrane proton (H +) ATPases (AHAs) have been proposed to energize pollen tube growth and underlie cell polarity, however, mechanistic evidence for this is lacking. Here we report that the combined loss of AHA6, AHA8, and AHA9 in Arabidopsis thaliana delays pollen germination and causes pollen tube growth defects, leading to drastically reduced fertility. Pollen tubes of aha mutants had reduced extracellular proton (H +) and anion fluxes, reduced cytosolic pH, reduced tip-toshank proton gradients, and defects in actin organization. Furthermore, mutant pollen tubes had less negative membrane potentials, substantiating a mechanistic role for AHAs in pollen tube growth through plasma membrane hyperpolarization. Our findings define AHAs as energy transducers that sustain the ionic circuit defining the spatial and temporal profiles of cytosolic pH, thereby controlling downstream pH-dependent mechanisms essential for pollen tube elongation, and thus plant fertility.

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confidence: 90%

Plasma membrane H+-ATPases sustain pollen tube growth and fertilization

et al. 2020

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“…• Extension of protrusion by exocytosis at the tip [189] by using vesicles from a pool maintained at the tip. (Spitzenkörper in fungi [16,17], clear zone and vesicle supply center [187,214])…”

Section: Tip At the Apexmentioning

confidence: 99%

Length control of long cell protrusions: rulers, timers and transport

Patra¹,

Chowdhury²,

Jülicher³

2022

Preprint

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A living cell uses long tubular appendages for locomotion and sensory purposes. Hence, assembling and maintaining a protrusion of correct length is crucial for its survival and overall performance. Usually the protrusions lack the machinery for the synthesis of building blocks and imports them from the cell body. What are the unique features of the transport logistics which facilitate the exchange of these building blocks between the cell and the protrusion? What kind of 'rulers' and 'timers' does the cell use for constructing its appendages of correct length on time? How do the multiple appendages coordinate and communicate among themselves during different stages of their existence? How frequently do the fluctuations drive the length of these dynamic protrusions out of the acceptable bounds? These questions are addressed from a broad perspective in this review which is organized in three parts. In part-I the list of all known cell protrusions is followed by a comprehensive list of the mechanisms of length control of cell protrusions reported in the literature. We review not only the dynamics of the genesis of the protrusions, but also their resorption and regrowth as well as regeneration after amputation. As a case study in part-II, the specific cell protrusion that has been discussed in detail is eukaryotic flagellum (also known as cilium); this choice was dictated by the fact that flagellar length control mechanisms have been studied most extensively over more than half a century in cells with two or more flagella. Although limited in scope, brief discussions on a few non-flagellar cell protrusions in part-III of this review is intended to provide a glimpse of the uncharted territories and challenging frontiers of research on subcellular length control phenomena that awaits vigorous investigations.

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“…Pollen tube (PT) tip growth is a highly polarized form of cell elongation ultimately leading to the delivery of sperm cells at the embryo sac and subsequent double fertilization ( Obermeyer and Feijó, 2017 ). The PT tip functions as the site of plasticity and extension, where vesicles filled with cell wall proteins and precursors fuse with the apical plasma membrane, providing extra membrane and cell wall material to the growing cell.…”

Section: Introductionmentioning

confidence: 99%

“…During its penetration down the style and transmitting tract toward the ovule, many interactive signals are exchanged between the PT and its surrounding tissue ( Qu et al, 2015 ; Obermeyer and Feijó, 2017 ). Upon reaching the female gametophyte, the PT encounters attracting signals that guide it to the synergids.…”

Section: Introductionmentioning

confidence: 99%

“…More so, Ca 2+ -signatures seem embedded throughout the male–female tissue crosstalk pathway ( Denninger et al, 2014 ; Hamamura et al, 2014 ). A number of highly dynamic cellular processes occur during PT growth ( Obermeyer and Feijó, 2017 ), including the formation and maintenance of intra- and extracellular ion dynamics, apical endo-/exocytosis and the modification of the cytoskeleton, all of which depend on tight spatial and temporal control of cytosolic [Ca 2+ ] oscillations at the tip ( Schoenaers et al, 2017 ). Pharmacological interruption of the apical cytoplasmic Ca 2+ gradient causes immediate growth cessation ( Iwano et al, 2009 ), and local elevation of the [Ca 2+ ] ext irreversibly steers tip growth directionality in vitro ( Bibikova et al, 1997 ).…”

Section: Introductionmentioning

confidence: 99%

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The Kinase ERULUS Controls Pollen Tube Targeting and Growth in Arabidopsis thaliana

et al. 2017

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In this paper, we describe the role of the receptor-like kinase ERULUS (ERU) in PT growth of Arabidopsis thaliana. In silico analysis and transcriptional reporter lines revealed that ERU is only expressed in pollen and root hairs (RHs), making it a tip growth-specific kinase. Deviations from Mendelian inheritance were observed in the offspring of self-pollinated heterozygous eru plants. We found that in vivo eru PT targeting was disturbed, providing a possible explanation for the observed decrease in eru fertilization competitiveness. Extracellular calcium perception and intracellular calcium dynamics lie at the basis of in vivo pollen tube (PT) tip growth and guidance. In vitro, ERU loss-of-function lines displayed no obvious PT phenotype, unless grown on low extracellular calcium ([Ca2+]ext) medium. When grown at 12 the normal [Ca2+]ext, eru PTs grew 37% slower relative to WT PTs. Visualization of cytoplasmic [Ca2+]cyt oscillations using the Yellow Cameleon 3.6 (YC3.6) calcium sensor showed that, unlike in WT PTs, eru apical [Ca2+]cyt oscillations occur at a lower frequency when grown at lower [Ca2+]ext, consistent with the observed reduced growth velocity. Our results show that the tip growth-specific kinase ERULUS is involved in regulating Ca2+-dependent PT growth, and most importantly, fertilization efficiency through successful PT targeting to the ovules.

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Pollen Tubes and Tip Growth: of Biophysics and Tipomics

Cited by 3 publications

References 30 publications

Plasma membrane H+-ATPases sustain pollen tube growth and fertilization

Plasma membrane H+-ATPases sustain pollen tube growth and fertilization

Length control of long cell protrusions: rulers, timers and transport

The Kinase ERULUS Controls Pollen Tube Targeting and Growth in Arabidopsis thaliana

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