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Science (New York, N.Y.) Dec 2017In flowering plants, fertilization requires complex cell-to-cell communication events between the pollen tube and the female reproductive tissues, which are controlled...
In flowering plants, fertilization requires complex cell-to-cell communication events between the pollen tube and the female reproductive tissues, which are controlled by extracellular signaling molecules interacting with receptors at the pollen tube surface. We found that two such receptors in , BUPS1 and BUPS2, and their peptide ligands, RALF4 and RALF19, are pollen tube-expressed and are required to maintain pollen tube integrity. BUPS1 and BUPS2 interact with receptors ANXUR1 and ANXUR2 via their ectodomains, and both sets of receptors bind RALF4 and RALF19. These receptor-ligand interactions are in competition with the female-derived ligand RALF34, which induces pollen tube bursting at nanomolar concentrations. We propose that RALF34 replaces RALF4 and RALF19 at the interface of pollen tube-female gametophyte contact, thereby deregulating BUPS-ANXUR signaling and in turn leading to pollen tube rupture and sperm release.
Topics: Arabidopsis; Arabidopsis Proteins; Fertilization; Ligands; Pollen Tube; Protein Kinases; Signal Transduction
PubMed: 29242234
DOI: 10.1126/science.aao3642 -
International Journal of Molecular... Feb 2023The aim of this Special Issue is to highlight the molecular dialogue between the pollen tube and the pistil [...].
The aim of this Special Issue is to highlight the molecular dialogue between the pollen tube and the pistil [...].
Topics: Pollen Tube; Cell Communication; Pollination; Flowers
PubMed: 36835118
DOI: 10.3390/ijms24043707 -
Science (New York, N.Y.) Jan 2022Fertilization of an egg by multiple sperm (polyspermy) leads to lethal genome imbalance and chromosome segregation defects. In , the block to polyspermy is facilitated...
Fertilization of an egg by multiple sperm (polyspermy) leads to lethal genome imbalance and chromosome segregation defects. In , the block to polyspermy is facilitated by a mechanism that prevents polytubey (the arrival of multiple pollen tubes to one ovule). We show here that FERONIA, ANJEA, and HERCULES RECEPTOR KINASE 1 receptor-like kinases located at the septum interact with pollen tube-specific RALF6, 7, 16, 36, and 37 peptide ligands to establish this polytubey block. The same combination of RALF (rapid alkalinization factor) peptides and receptor complexes controls pollen tube reception and rupture inside the targeted ovule. Pollen tube rupture releases the polytubey block at the septum, which allows the emergence of secondary pollen tubes upon fertilization failure. Thus, orchestrated steps in the fertilization process in are coordinated by the same signaling components to guarantee and optimize reproductive success.
Topics: Arabidopsis; Arabidopsis Proteins; Fertilization; Ligands; Ovule; Peptides; Phosphotransferases; Pollen; Pollen Tube; Pollination; Protein Kinases; Signal Transduction
PubMed: 35050671
DOI: 10.1126/science.abl4683 -
International Journal of Molecular... Jan 2019The pollen tube was a fundamental step forward in the evolution of terrestrial plants; in fact, it allowed plants to liberate themselves from water demand during...
The pollen tube was a fundamental step forward in the evolution of terrestrial plants; in fact, it allowed plants to liberate themselves from water demand during reproduction [...].
Topics: Plant Physiological Phenomena; Pollen Tube; Reproduction
PubMed: 30691221
DOI: 10.3390/ijms20030531 -
The New Phytologist Oct 2018
Topics: Cell Wall; Mechanical Phenomena; Plant Proteins; Pollen Tube; Pollination
PubMed: 30156021
DOI: 10.1111/nph.15358 -
International Journal of Molecular... Nov 2021Angiosperm mature pollen represents a quiescent stage with a desiccated cytoplasm surrounded by a tough cell wall, which is resistant to the suboptimal environmental... (Review)
Review
Angiosperm mature pollen represents a quiescent stage with a desiccated cytoplasm surrounded by a tough cell wall, which is resistant to the suboptimal environmental conditions and carries the genetic information in an intact stage to the female gametophyte. Post pollination, pollen grains are rehydrated, activated, and a rapid pollen tube growth starts, which is accompanied by a notable metabolic activity, synthesis of novel proteins, and a mutual communication with female reproductive tissues. Several angiosperm species (, tobacco, maize, and kiwifruit) were subjected to phosphoproteomic studies of their male gametophyte developmental stages, mostly mature pollen grains. The aim of this review is to compare the available phosphoproteomic studies and to highlight the common phosphoproteins and regulatory trends in the studied species. Moreover, the pollen phosphoproteome was compared with root hair phosphoproteome to pinpoint the common proteins taking part in their tip growth, which share the same cellular mechanisms.
Topics: Phosphoproteins; Plant Proteins; Pollen Tube; Pollination; Proteome; Proteomics
PubMed: 34830092
DOI: 10.3390/ijms222212212 -
Plant Signaling & Behavior 2018Vacuoles are versatile organelles in plant cells, critical for growth and responses to environmental cues. Vacuoles are dynamic tubular structures in pollen tubes, the... (Review)
Review
Vacuoles are versatile organelles in plant cells, critical for growth and responses to environmental cues. Vacuoles are dynamic tubular structures in pollen tubes, the male gametophytes. Mutations at vacuolar fusion machinery caused male gametophytic lethality by affecting pollen tube growth and guidance, which are critical steps leading to angiosperm reproduction. In comparison, the role of vacuolar trafficking and its cargoes in this process is less understood. In this mini-review, we summarize old and recent findings that indicate the involvement of vacuolar trafficking in pollen tube growth and guidance. We also point at future studies that would provide insights into a key role of vacuolar trafficking and its cargos in pollen tube growth and guidance.
Topics: Arabidopsis; Arabidopsis Proteins; Pollen Tube; Vacuoles
PubMed: 29701540
DOI: 10.1080/15592324.2018.1464854 -
Plant Physiology Jan 2017Pollen tube guidance in flowering plants is a unique and critical process for successful sexual reproduction. The pollen tube that grows from pollen, which is the male... (Review)
Review
Pollen tube guidance in flowering plants is a unique and critical process for successful sexual reproduction. The pollen tube that grows from pollen, which is the male gametophyte, precisely navigates to the embryo sac, which is the female gametophyte, within the pistil. Recent advances have clarified the molecular framework of gametophytic pollen tube guidance. Multiple species-specific attractant peptides are secreted from synergid cells, the proper development and function of which are regulated by female gametes. Multiple receptor-like kinases on the pollen tube tip are involved in sensing species-specific attractant peptides. In this Update article, recent progress in our understanding of the mechanism of gametophytic pollen tube guidance is reviewed, including attraction by synergid cells, control of pollen tube guidance by female gametes, and directional growth of the pollen tube by directional cue sensing. Future directions in the study of pollen tube guidance also are discussed.
Topics: Models, Biological; Ovule; Peptides; Pollen Tube
PubMed: 27920159
DOI: 10.1104/pp.16.01571 -
The New Phytologist Nov 2021All kingdoms of life have evolved tip-growing cells able to mine their environment or deliver cargo to remote targets. The basic cellular processes supporting these... (Review)
Review
All kingdoms of life have evolved tip-growing cells able to mine their environment or deliver cargo to remote targets. The basic cellular processes supporting these functions are understood in increasing detail, but the multiple interactions between them lead to complex responses that require quantitative models to be disentangled. Here, I review the equations that capture the fundamental interactions between wall mechanics and cell hydraulics starting with a detailed presentation of James Lockhart's seminal model. The homeostatic feedbacks needed to maintain a steady tip velocity are then shown to offer a credible explanation for the pulsatile growth observed in some tip-growing cells. Turgor pressure emerges as a central variable whose role in the morphogenetic process has been a source of controversy for more than 50 yr. I argue that recasting Lockhart's work as a process of chemical stress relaxation can clarify how cells control tip growth and help us internalise the important but passive role played by turgor pressure in the morphogenetic process.
Topics: Cell Cycle; Cell Differentiation; Cell Wall; Pollen Tube; Pollination
PubMed: 34492127
DOI: 10.1111/nph.17722 -
Annals of Botany Sep 2011Pollination is a crucial step in angiosperm (flowering plant) reproduction. Highly orchestrated pollen-pistil interactions and signalling events enable plant species to... (Review)
Review
BACKGROUND
Pollination is a crucial step in angiosperm (flowering plant) reproduction. Highly orchestrated pollen-pistil interactions and signalling events enable plant species to avoid inbreeding and outcrossing as a species-specific barrier. In compatible pollination, pollen tubes carrying two sperm cells grow through the pistil transmitting tract and are precisely guided to the ovules, discharging the sperm cells to the embryo sac for fertilization.
SCOPE
In Lilium longiflorum pollination, growing pollen tubes utilize two critical mechanisms, adhesion and chemotropism, for directional growth to the ovules. Among several molecular factors discovered in the past decade, two small, secreted cysteine-rich proteins have been shown to play major roles in pollen tube adhesion and reorientation bioassays: stigma/style cysteine-rich adhesin (SCA, approx. 9·3 kDa) and chemocyanin (approx. 9·8 kDa). SCA, a lipid transfer protein (LTP) secreted from the stylar transmitting tract epidermis, functions in lily pollen tube tip growth as well as in forming the adhesive pectin matrix at the growing pollen tube wall back from the tip. Lily chemocyanin is a plantacyanin family member and acts as a directional cue for reorienting pollen tubes. Recent consecutive studies revealed that Arabidopsis thaliana homologues for SCA and chemocyanin play pivotal roles in tip polarity and directionality of pollen tube growth, respectively. This review outlines the biological roles of various secreted proteins in angiosperm pollination, focusing on plant LTPs and chemocyanin.
Topics: Antigens, Plant; Arabidopsis; Carrier Proteins; Lilium; Plant Proteins; Pollen Tube; Reproduction
PubMed: 21307038
DOI: 10.1093/aob/mcr015