hypha

Examples of hypha in the following topics:

• Fungi Cell Structure and Function

  • The vegetative stage consists of a tangle of slender thread-like structures called hyphae (singular, hypha), whereas the reproductive stage can be more conspicuous.
  • The mass of hyphae is a mycelium .
  • The hyphae in bread molds (which belong to the Phylum Zygomycota) are not separated by septa.
  • Fungal hyphae may be (a) septated or (b) coenocytic (coeno- = "common"; -cytic = "cell") with many nuclei present in a single hypha.
  • A bright field light micrograph of (c) Phialophora richardsiae shows septa that divide the hyphae.

• Ascomycota: The Sac Fungi

  • Filamentous ascomycetes produce hyphae divided by perforated septa, allowing streaming of cytoplasm from one cell to the other.
  • Conidia and asci, which are used respectively for asexual and sexual reproductions, are usually separated from the vegetative hyphae by blocked (non-perforated) septa.
  • Sexual reproduction starts with the development of special hyphae from either one of two types of mating strains .
  • Special ascogenous hyphae arise, in which pairs of nuclei migrate: one from the "male" strain and one from the "female" strain.
  • The ascospores are then released, germinate, and form hyphae that are disseminated in the environment and start new mycelia .

• Mycorrhizae: The Symbiotic Relationship between Fungi and Roots

  • Mycorrhizae help increase the surface area of the plant root system because hyphae, which are narrow, can spread beyond the nutrient depletion zone.
  • Hyphae are long extensions of the fungus, which can grow into small soil pores that allow access to phosphorus otherwise unavailable to the plant .
  • Hyphae from the fungi extend from the mantle into the soil, which increases the surface area for water and mineral absorption.
  • Hyphae proliferate within the mycorrhizae, which appears as off-white fuzz in this image.
  • These hyphae greatly increase the surface area of the plant root, allowing it to reach areas that are not depleted of nutrients.

• Basidiomycota: The Club Fungi

  • The fungi in the Phylum Basidiomycota are easily recognizable under a light microscope by their club-shaped fruiting bodies called basidia (singular, basidium), which are the swollen terminal cell of a hypha.
  • The "gills" are actually compacted hyphae on which the basidia are borne.
  • The haploid nuclei migrate into basidiospores, which germinate and generate monokaryotic hyphae.
  • The lifecycle of a basidiomycete alternates generation with a prolonged stage in which two nuclei (dikaryon) are present in the hyphae.

• Fungi Reproduction

  • Fragments of hyphae can grow new colonies.
  • Conidiospores are unicellular or multicellular spores that are released directly from the tip or side of the hypha.
  • Other asexual spores originate in the fragmentation of a hypha to form single cells that are released as spores; some of these have a thick wall surrounding the fragment.
  • This bright field light micrograph shows the release of spores from a sporangium at the end of a hypha called a sporangiophore.

• Mutualistic Relationships with Fungi and Fungivores

  • In a mycorrhizal association, the fungal mycelia use their extensive network of hyphae and large surface area in contact with the soil to channel water and minerals from the soil into the plant, thereby increasing a plant's nutrient uptake.
  • Ectomycorrhizae ("outside" mycorrhiza) depend on fungi enveloping the roots in a sheath (called a mantle) and a Hartig net of hyphae that extends into the roots between cells .
  • The body of a lichen, referred to as a thallus, is formed of hyphae wrapped around the photosynthetic partner .
  • This cross-section of a lichen thallus shows the (a) upper cortex of fungal hyphae, which provides protection; the (b) algal zone where photosynthesis occurs, the (c) medulla of fungal hyphae, and the (d) lower cortex, which also provides protection and may have (e) rhizines to anchor the thallus to the substrate.

• Deuteromycota: The Imperfect Fungi

  • Some hyphae may recombine and form heterokaryotic hyphae.

• Glomeromycota

  • It appears that most members of this family form arbuscular mycorrhizae: the hyphae interact with the root cells forming a mutually-beneficial association where the plants supply the carbon source and energy in the form of carbohydrates to the fungus while the fungus supplies essential minerals from the soil to the plant.
  • They have coenocytic hyphae and reproduce asexually, producing glomerospores.

• Zygomycota: The Conjugated Fungi

  • Zygomycetes have a thallus of coenocytic hyphae in which the nuclei are haploid when the organism is in the vegetative stage.
  • Two opposing mating strains (type + and type –) must be in close proximity for gametangia (singular: gametangium) from the hyphae to be produced and fuse, leading to karyogamy .

• Chytridiomycota: The Chytrids

  • Most chytrids are unicellular; a few form multicellular organisms and hyphae, which have no septa between cells (coenocytic).