What do the terms phycobiont and mycobiont signify?
Explanation Lichens are the mutualistic, or rather symbiotic association of photosynthetic algae and fungi. The photosynthetic partners, that are algae; also known as Phycobionts in this case, are typically unicellular or multicellular green algae or cyanobacteria. The fungal component; also known as Mycobionts in this case, may be a member of ascomycetes(mostly) or a member of basidiomycetes(in a few cases), which are two of the four major divisions of fungi. The fungus (Mycobionts) usually gives a lichen its overall shape and structure, and tissues formed by hyphae account for most of the lichen’s mass. Hyphae are the structural, long filamentous units of dense myecelliumnetwork. The algal partners (Phycobionts) generally occupy an inner layer below the lichen surface.The Phycobionts provide carbon compounds which are simple carbohydrates by photosynthesis; the cyanobacteria also fix nitrogen and provide organic nitrogen. The Mycobionts provide their photosynthetic partners with a suitable environment for growth. The physical arrangement of hyphaeallows gas exchange for absorbing water vapour from the environment, protects the photosynthic partner which is light sensitive by providing it much-needed shade, and retains water and minerals. The fungi of many lichens reproduce sexually by forming ascocarps or basidiocarps whereas algal partner reproduce independently of the fungus by asexual cell division. An important point to note is that Phycobionts are predominent and Mycobionts are subordinate partners. Final Answer The terms Phycobionts and Mycobionts signify the symbiotic relationship of Algae and Fungi in Lichens.
