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pollen tube definition
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pollen tube definition

In order to experimentally observe distributional changes that take place in the actin cytoskeleton during pollen tube growth, green fluorescent proteins(GFPs) have been put to use. The maximum length of the F-actin cables were shorter in the rmd-mutant pollen tubes compared to those in the wild type tubes. [26] Lifeact-mEGFP has been used as a marker to study the dynamics of actin filaments in the growing pollen tubes of tobacco, lilies and Arabidopsis. [2], Class I formin AtFH3 is another actin nucleation factor. Information about pollen tube in the AudioEnglish.org dictionary, synonyms and antonyms. [8][17], Calcium and ethylene in Arabidopsis thaliana were involved in termination of the pollen tube when it grows near the ovary. In this region, actin filaments are arranged into axial bundles of uniform polarity, thereby enabling the transport of various organelles and vesicles from the base of the pollen tube to the tip, propelling overall tube growth. The pollen tube is highly branched and grows on the female sporophyte tissues. In most species the plants are wind-pollinated, and the pollen grains of conifers have air bladders that provide buoyancy in air currents. The pollen tube acts as a conduit to transport the male gamete cells from the pollen grain—either from the stigma (in flowering plants) to the ovules at the base of the pistil or directly through ovule tissue in some gymnosperms. In the apical region - the site of tip-directed growth- actin filaments are less abundant, however they are highly dynamic. Genetic knockouts of AtFH5 resulted in a decreased abundance of actin filaments in both apical and subapical regions of the pollen tube, thereby providing more evidence to support the theory that AtFH5 nucleates actin filament assembly in apical and subapical regions of the pollen tube. Fig. Therefore, this shows that RMD is localized within the tip of the pollen tube. See more. There is great variation in pollen tubes in angiosperms and many model plants like petunia, Arabidopsis, lily and tobacco plants have been studied for intraspecific variation and signaling mechanisms. The pollen tubes of the wild-type plants had a greater pollen tube length than the mutants, but the mutants had a greater tube width. Quick definitions from WordNet (pollen tube) noun: slender tubular outgrown from a pollen grain that penetrates the ovule and releases male gametes Also see pollen_tubes Words similar to pollen tube Usage examples for pollen tube Words that often appear near pollen tube [37] The homogalacturonans accumulate in the apex region via exocytosis in order to loosen the cell wall. All Free. These two methods demonstrated that there was an abundant presence of the RMD transcripts in the lemma, pistil, anther, and mature pollen grains. Pollen tube growth is toward eggs of the same species as the pollen. After the germination rates were tested, there was a comparison of the lengths and widths of the pollen tubes between the two plants. [24] In terms of spatial distribution, actin filaments are arranged into three different structures within the pollen tube. AtFH3 nucleates actin filament assembly of the longitudinal actin cables located in the shank region of the pollen tube. Outcrossed pollen grows more successfully. Other articles where Pollen tube is discussed: angiosperm: Pollination: The pollen tube ultimately enters an ovule through the micropyle and penetrates one of the sterile cells on either side of the egg (synergids). How many readers could get excited by the fact that a single primrose plant can produce two kinds of flowers, virtually identical but one with a long style (the stalk that channels, Post the Definition of pollen tube to Facebook, Share the Definition of pollen tube on Twitter, We Got You This Article on 'Gift' vs. 'Present'. Nevertheless, several aspects have already been identified as central in the process of pollen tube growth. One such method of transport involves traveling through the style from the stigma. [9] Polypeptides found in the style also regulate growth of tube and specific peptides that play a role in signaling for growth have been identified. Ans. These synergids begin to degenerate immediately after pollination. Double-strand breaks in DNA that arise appear to be efficiently repaired in the generative cell, but not in the vegetative cell, during the transport process to the female gametophyte.[34]. [15][16], There is great variation in the rate of growth of pollen tubes and many studies have focused on signaling. This indicates the presence of membrane-anchored actin nucleation factors. In cycads, however, various enzymes have been identified in the pollen tube that direct growth and the nucellus tissues are more damaged with the tube growth. Meaning of pollen tube. pollen tube: A slender tube that is formed by a pollen grain of a seed plant and penetrates the ovule, where it releases the male gametes. Learn a new word every day. Pollen grains undergo dehydration to reduce their mass so that they can be easily moved from one flower to another. See Fig. [17], The length of the pollen tube varies by species. Fluorescent intensity was measured using statistical analysis in order to observe the actin filament densities within the pollen tubes. For example, GFP-mTalin resulted in excessive filament bundling and GFP-fimbrin/ABD2-GFP did not label actin filaments located in the apical or subapical regions of the pollen tube. Individual pollen grains are small enough to require magnification to see detail. Meaning of pollen tube. The pollen tube of most seed plants acts as a passageway. Learn more. The pollen tube formation is complex and the mechanism is not fully understood, but is of great interest to scientists. Definition of pollen tube in the Definitions.net dictionary. In order to determine the polarity of the actin cables, the angles between the actin cables and elongation axis of the pollen tube were measured. The actin filaments in the cytoskeleton, the peculiar cell wall, secretory vesicle dynamics, and the flux of ions, to name a few, are some of the fundamental features readily identified as crucial, but whose role has not yet been completely elucidated. See more. [21] The angiosperm pollen tube is simple, unbranched, and fast growing, however this is not the case for ancestral plants. Pollen tubes are unique to plants and their structures have evolved over the history of plants. (botany) a slender tubular outgrowth from a pollen grain when deposited on the stigma for a flower; it penetrates the style and conveys the male gametes to the ovule Familiarity information: POLLEN TUBE used as a noun is very rare. The actin cytoskeleton is an important factor in pollen tube growth, because there are different patterns of actin cytoskeleton within the different regions of the pollen tube for the maintenance of polarized cell growth. An essential protein required for this tip growth is the actin-organizing protein and type II formin protein called Rice Morphology Determinant (RMD). The sperm cells are the male gametes that will join with the egg cell and the central cell in double fertilization. The LURE peptides that are secreted from the synergids, which occupy the space adjacent to the egg cell, can use attractants. Therefore, these results support that RMD is essential for controlling pollen germination. 255 Pollen tube . Such events are essential for regulating the velocity and direction of pollen tube growth. A pollen grain itself is not the male gamete. [42][43], RMD promotes pollen germination and pollen tube growth, and this is proven through numerous experiments. pollen tube: 1 n (botany) a slender tubular outgrowth from a pollen grain when deposited on the stigma for a flower; it penetrates the style and conveys the male gametes to the ovule Type of: plant part , plant structure any part of a plant or fungus [27] Such experimentation has made a connection between the dynamics of tip-localized actin filaments and their role in the formation of actin structures in the subapical region. Therefore, pollen must submerge through the pollination droplet which brings the male gametophyte to the egg of the exposed ovule. First, pollen grains were collected from proRMD::GUS trangenic plants, and it was noted that there was a strong GUS signal within these mature pollen grains. 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