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International Journal of Molecular... Jan 2019Pollen is the male gametophyte of higher plants. Its major function is to deliver sperm cells to the ovule to ensure successful fertilization. During this process, many... (Review)
Review
Pollen is the male gametophyte of higher plants. Its major function is to deliver sperm cells to the ovule to ensure successful fertilization. During this process, many interactions occur among pollen tubes and pistil cells and tissues, and calcium ion (Ca) dynamics mediate these interactions among cells to ensure that pollen reaches the embryo sac. Although the precise functions of Ca dynamics in the cells are unknown, we can speculate about its roles on the basis of its spatial and temporal characteristics during these interactions. The results of many studies indicate that calcium is a critical element that is strongly related to pollen germination and pollen tube growth.
Topics: Calcium; Flowers; Germination; Plant Development; Plant Physiological Phenomena; Pollen; Pollen Tube
PubMed: 30669423
DOI: 10.3390/ijms20020420 -
Molecular Plant Mar 2017Maize is the most important agricultural crop used for food, feed, and biofuel as well as a raw material for industrial products such as packaging material. To increase... (Review)
Review
Maize is the most important agricultural crop used for food, feed, and biofuel as well as a raw material for industrial products such as packaging material. To increase yield and to overcome hybridization barriers, studies of maize gamete development, the pollen tube journey, and fertilization mechanisms were initiated more than a century ago. In this review, we summarize and discuss our current understanding of the regulatory components for germline development including sporogenesis and gametogenesis, the progamic phase of pollen germination and pollen tube growth and guidance, as well as fertilization mechanisms consisting of pollen tube arrival and reception, sperm cell release, fusion with the female gametes, and egg cell activation. Mechanisms of asexual seed development are not considered here. While only a few molecular players involved in these processes have been described to date and the underlying mechanisms are far from being understood, maize now represents a spearhead of reproductive research for all grass species. Recent development of essentially improved transformation and gene-editing systems may boost research in this area in the near future.
Topics: Fertilization; Ovule; Plant Proteins; Pollen Tube; Zea mays
PubMed: 28267957
DOI: 10.1016/j.molp.2017.01.012 -
Planta Jan 2021In flowering plants, pollen germination on the stigma and pollen tube growth in pistil tissues are critical for sexual plant reproduction, which are involved in the... (Review)
Review
In flowering plants, pollen germination on the stigma and pollen tube growth in pistil tissues are critical for sexual plant reproduction, which are involved in the interactions between pollen/pollen tube and pistil tissues. GPI-anchored proteins (GPI-APs) are located on the external surface of the plasma membrane and function in various processes of sexual plant reproduction. The evidences suggest that GPI-APs participate in endosome machinery, Ca oscillations, the development of the transmitting tract, the maintenance of the integrity of pollen tube, the enhancement of interactions of the receptor-like kinase (RLK) and ligand, and guidance of the growth of pollen tube, and so on. In this review, we will summarize the recent progress on the roles of GPI-APs in the interactions between pollen/pollen tube and pistil tissues during pollination, such as pollen germination on the stigma, pollen tube growth in the transmitting tract, pollen tube guidance to the ovule, and pollen tube reception in the embryo sac. We will also discuss the future outlook of GPI-APs in the interactions between pollen/pollen tube and pistil tissues.
Topics: Flowers; GPI-Linked Proteins; Ovule; Plant Proteins; Pollen Tube; Pollination; Research
PubMed: 33394122
DOI: 10.1007/s00425-020-03526-8 -
Biochimica Et Biophysica Acta Sep 2016During evolution, the male gametophyte of Angiosperms has been severely reduced to the pollen grain, consisting of a vegetative cell containing two sperm cells. This... (Review)
Review
During evolution, the male gametophyte of Angiosperms has been severely reduced to the pollen grain, consisting of a vegetative cell containing two sperm cells. This vegetative cell has to deliver the sperm cells from the stigma through the style to the ovule. It does so by producing a pollen tube and elongating it to many centimeters in length in some species, requiring vast amounts of fatty acid and membrane lipid synthesis. In order to optimize this polar tip growth, a unique lipid composition in the pollen has evolved. Pollen tubes produce extraplastidial galactolipids and store triacylglycerols in lipid droplets, probably needed as precursors of glycerolipids or for acyl editing. They also possess special sterol and sphingolipid moieties that might together form microdomains in the membranes. The individual lipid classes, the proteins involved in their synthesis as well as the corresponding Arabidopsis knockout mutant phenotypes are discussed in this review. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.
Topics: Galactolipids; Gene Expression Regulation, Plant; Lipid Droplets; Lipids; Pollen; Pollen Tube; Signal Transduction; Triglycerides
PubMed: 27033152
DOI: 10.1016/j.bbalip.2016.03.023 -
International Journal of Molecular... Nov 2018In non-cleistogamous plants, the male gametophyte, the pollen grain is immotile and exploits various agents, such as pollinators, wind, and even water, to arrive to a... (Review)
Review
In non-cleistogamous plants, the male gametophyte, the pollen grain is immotile and exploits various agents, such as pollinators, wind, and even water, to arrive to a receptive stigma. The complex process of pollination involves a tubular structure, i.e., the pollen tube, which delivers the two sperm cells to the female gametophyte to enable double fertilization. The pollen tube has to penetrate the stigma, grow in the style tissues, pass through the septum, grow along the funiculus, and navigate to the micropyle of the ovule. It is a long journey for the pollen tube and its two sperm cells before they meet the female gametophyte, and it requires very accurate regulation to perform successful fertilization. In this review, we update the knowledge of molecular dialogues of pollen-pistil interaction, especially the progress of pollen tube activation and guidance, and give perspectives for future research.
Topics: Adhesiveness; Flowers; Germination; Pollen Tube; Water
PubMed: 30423936
DOI: 10.3390/ijms19113529 -
Current Opinion in Plant Biology Dec 2015Fertilization is an important life event for sexually reproductive plants. Part of this process involves precise regulation of a series of complicated cell-cell... (Review)
Review
Fertilization is an important life event for sexually reproductive plants. Part of this process involves precise regulation of a series of complicated cell-cell communications between male and female tissues. Through genetic and omics approaches, many genes and proteins involved in this process have been identified. Here we review our current understanding of signaling components during fertilization. We will especially focus on LURE peptides and related signaling events that are required for micropylar pollen tube guidance. We will also summarize signaling events required for termination of micropylar pollen tube guidance after fertilization.
Topics: Fertilization; Gene Expression Regulation, Plant; Peptides; Plant Proteins; Pollen Tube; Pollination; Signal Transduction
PubMed: 26580200
DOI: 10.1016/j.pbi.2015.10.006 -
International Journal of Molecular... Mar 2021Angiosperm reproduction relies on the precise growth of the pollen tube through different pistil tissues carrying two sperm cells into the ovules' embryo sac, where they... (Review)
Review
Angiosperm reproduction relies on the precise growth of the pollen tube through different pistil tissues carrying two sperm cells into the ovules' embryo sac, where they fuse with the egg and the central cell to accomplish double fertilization and ultimately initiate seed development. A network of intrinsic and tightly regulated communication and signaling cascades, which mediate continuous interactions between the pollen tube and the sporophytic and gametophytic female tissues, ensures the fast and meticulous growth of pollen tubes along the pistil, until it reaches the ovule embryo sac. Most of the pollen tube growth occurs in a specialized tissue-the transmitting tract-connecting the stigma, the style, and the ovary. This tissue is composed of highly secretory cells responsible for producing an extensive extracellular matrix. This multifaceted matrix is proposed to support and provide nutrition and adhesion for pollen tube growth and guidance. Insights pertaining to the mechanisms that underlie these processes remain sparse due to the difficulty of accessing and manipulating the female sporophytic tissues enclosed in the pistil. Here, we summarize the current knowledge on this key step of reproduction in flowering plants with special emphasis on the female transmitting tract tissue.
Topics: Extracellular Matrix; Fertilization; Flowers; Magnoliopsida; Ovule; Plant Proteins; Pollen Tube; Seeds; Signal Transduction
PubMed: 33807566
DOI: 10.3390/ijms22052603 -
Journal of Integrative Plant Biology Jan 2015
Topics: Actin Cytoskeleton; Movement; Myosins; Organelles; Plant Proteins; Plants; Pollen Tube
PubMed: 25494628
DOI: 10.1111/jipb.12318 -
Plant Physiology Jun 2020To reach the female gametophyte, growing pollen tubes must penetrate different tissues within the pistil, the female reproductive organ of a flower. Past research has...
To reach the female gametophyte, growing pollen tubes must penetrate different tissues within the pistil, the female reproductive organ of a flower. Past research has identified various chemotropic cues that guide pollen tubes through the transmitting tract of the pistil, which represents the longest segment of its growth path. In addition, physical mechanisms also play a role in pollen tube guidance; however, these processes remain poorly understood. Here we show that pollen tubes from plants with solid transmitting tracts actively respond to the stiffness of the environment. We found that pollen tubes from and other plant species with a solid or semisolid transmitting tract increase their growth rate in response to an increasing matrix stiffness. By contrast, pollen tubes from and other plant species with a hollow transmitting tract decrease their growth rate with increasing matrix stiffness, even though the forces needed to maintain a constant growth rate remain far below the maximum penetration force these pollen tubes are able to generate. Moreover, when confronted with a transition from a softer to a stiffer matrix, pollen tubes from display a greater ability to penetrate into a stiffer matrix compared with pollen tubes from even though the maximum force generated by pollen tubes from (11 µN) is smaller than the maximum force generated by pollen tubes from (36 µN). These findings demonstrate a mechano-sensitive growth behavior, termed here durotropic growth, that is only expressed in pollen tubes from plants with a solid or semisolid transmitting tract and thus may contribute to an effective pollen tube guidance within the pistil.
Topics: Flowers; Lilium; Plant Proteins; Pollen Tube; Nicotiana
PubMed: 32241878
DOI: 10.1104/pp.19.01505 -
Plant & Cell Physiology Nov 2021Many plant processes occur in the context of and in interaction with a surrounding matrix such as soil (e.g. root growth and root-microbe interactions) or surrounding... (Review)
Review
Many plant processes occur in the context of and in interaction with a surrounding matrix such as soil (e.g. root growth and root-microbe interactions) or surrounding tissues (e.g. pollen tube growth through the pistil), making it difficult to study them with high-resolution optical microscopy. Over the past decade, microfabrication techniques have been developed to produce experimental systems that allow researchers to examine cell behavior in microstructured environments that mimic geometrical, physical and/or chemical aspects of the natural growth matrices and that cannot be generated using traditional agar plate assays. These microfabricated environments offer considerable design flexibility as well as the transparency required for high-resolution, light-based microscopy. In addition, microfluidic platforms have been used for various types of bioassays, including cellular force assays, chemoattraction assays and electrotropism assays. Here, we review the recent use of microfluidic devices to study plant cells and organs, including plant roots, root hairs, moss protonemata and pollen tubes. The increasing adoption of microfabrication techniques by the plant science community may transform our approaches to investigating how individual plant cells sense and respond to changes in the physical and chemical environment.
Topics: Biological Assay; Bryophyta; Imaging, Three-Dimensional; Microfluidic Analytical Techniques; Plant Cells; Plant Roots; Pollen Tube; Protoplasts
PubMed: 34027549
DOI: 10.1093/pcp/pcab067