Germinating conidiospores of Hyaloperonospora parasitica. Observe the appressorium on top right.
An appressorium is a specialized cell typical of many fungal plant pathogens that is used to infect host plants. It is a flattened, hyphal "pressing" organ, from which a minute infection peg grows and enters the host, using turgor pressure capable of punching through even Mylar.[1][2]
Following spore attachment and germination on the host surface, the emerging germ tube perceives physical cues such as surface hardness and hydrophobicity, as well as chemical signals including wax monomers that trigger appressorium formation. Appressorium formation begins when the tip of the germ tube ceases polar growth, hooks, and begins to swell. The contents of the spore are then mobilized into the developing appressorium, a septum develops at the neck of the appressorium, and the germ tube and spore collapse and die. As the appressorium matures, it becomes firmly attached to the plant surface and a dense layer of melanin is laid down in the appressorium wall, except across a pore at the plant interface. Turgor pressure increases inside the appressorium and a penetration hypha emerges at the pore, which is driven through the plant cuticle into the underlying epidermal cells. The osmotic pressure exerted by the appressorium can reach up to 8 MPa, which allows it to puncture the plant cuticle.[3] This pressure is achievable due to a melanin-pigmented cell wall which is impermeable to compounds larger than water molecules, so the highly-concentrated ions cannot escape from it.[4]
^Cite error: The named reference Howard1991 was invoked but never defined (see the help page).
^Cite error: The named reference Howard1996 was invoked but never defined (see the help page).
^Fitopatologia. T. 1, Podstawy fitopatologii. Selim Kryczyński, Zbigniew Weber, Barbara Gołębniak. Poznań: Powszechne Wydawnictwo Rolnicze i Leśne. 2010. ISBN 978-83-09-01063-0. OCLC 802060485.{{cite book}}: CS1 maint: others (link)
^Howard, Richard J.; Ferrari, Margaret A. (1989-12-01). "Role of melanin in appressorium function". Experimental Mycology. 13 (4): 403–418. doi:10.1016/0147-5975(89)90036-4. ISSN 0147-5975.
An appressorium is a specialized cell typical of many fungal plant pathogens that is used to infect host plants. It is a flattened, hyphal "pressing" organ...
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and culm nodes. Using a structure called an appressorium, the pathogen penetrates the plant. The appressorium cell wall is chitinous and its inner side...
2013-08-21. Zhu, M.; et al. (2017). "Very-long-chain aldehydes induce appressorium formation in ascospores of the wheat powdery mildew fungus Blumeria graminis"...
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germ tube which develops an appressorium, or 'pressing' organ. As the germ tube grows, it pulls the spore and the appressorium together, causing an indentation...
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attach to the plant by which through growth they begin to produce an appressorium which penetrates the plant cell and allows for the pathogen to obtain...
The spores produce an appressorium which in turn produces a penetration peg. This hypha grows from bottom of the appressorium and works its way through...
appressed Flattened, or closely applied; e.g. of scales or fibers. appressorium A swelling at the end of a germ tube or other hypha that adheres to the...
conidia. F. Direct penetration of the germ tube through a stoma. G. Appressorium-like structure formed in the antestomatal chamber. H. Secondary conidia...
other fungi using lectins on the host fungi as a receptor, forming an appressorium. Once this is formed, Trichoderma inject toxic enzymes into the host...
form a structure called an appressorium that evolved to puncture plant tissues. The pressure generated by the appressorium, directed against the plant...
into the walls of the appressorium to create turgor pressure in the appressorium. The melanin allows water into the appressorium cell but nothing out....
the germ tube, whose apical section differentiates into a melanised appressorium. This structure will then function to penetrate the plant cell cuticle...
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produce a single germ tube that grows across the leaf surface, until an appressorium forms. Appressoria form over anticlinal walls or over the center of epidermal...
its host, as does Blasiphalia. Instead, Rickenella produces a small appressorium or no appressoria and penetrates the rhizoids of its moss hosts, growing...
stomata, or penetrate directly through the top of the leaf, using its appressorium, infecting the leaf within 12 hours. In the orchard, Alternaria citri...
the appressorium appears the same, as a simple swelling at the end of a hypha, closely appressed to the eggshell. Adhesion between the appressorium and...
surface of a host plant. The conidia then develop germ tubes, forming an appressorium, that later forms into haustoria. These haustoria are used to siphon...
for photosynthesis. Following conidia germination, the fungus forms an appressorium, which penetrates the corn leaf cell directly using an infection hypha...
gloeosporioides conidium lands upon a susceptible host it will first produce an appressorium. This specialized structure allows the pathogen to penetrate the host...
teres) makes up to 3 conidia per conidiophore. It infects plants with an appressorium. It grows bio-trophically in the first infected plant cell, but then...
disease. Once the rice sheath has been inoculated, the pathogen forms an appressorium and infection cushions. Both intercellular and intracellular hyphae are...
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