Lichens are fungi that have discovered agriculture. — Trevor Goward
**Abstract:** The research topic is lichen, specifically in its assembly, dormancy, and growth pattern. Lichen is more of a colony than an organism. Through symbiotic relationships, fungi and algae manage to collaborate and achieve a more efficient, resilient, and balanced overall strategy. For instance, the lichen has no root, so it absorbs moisture directly from the air. When the moisture level is high, it produces sugar through photosynthesis and stores the moist within its thallus. When the wet level drops, the lichen slowly dries up, following its environment. Eventually, it goes into dormancy and remains inactive until the air is humid again. This significant pattern is a result of the mutualistic relationship between the algal and fungal partners. It is both efficient and adaptive energetically, allowing the lichen to live beyond harsh environmental cycles.
A Lichen is a composite organism that arises from algae or cyanobacteria living among multiple fungi species' filaments in a symbiotic relationship. Lichens have properties different from those of their component organisms. There are three major types of lichens, and Fruticose has a **shrub-**like mycelium, Folios has some leave-like thallus, crustose imitates a thin layer of cells substrate.
Lichenization is a particular form of life of 20% fungal species. In this relationship, the fungal part is called mycobiont, mostly made up with mycelium. The algae and cyanobacteria living within the phallus is called photobiont. And some yeasts may be found critical to the system, where they produce energy through fermentation. In this way, a lichen is a versatile system that are very adaptive to the chemical alternation of its habitat.
The flow of energy & product within a lichen
Let's take a closer look. Within the algae layer, there is a hypha growing towards an alga cell. It will wrap around it and penetrate it to extract the sugar in the alga.
Hyphae wrap and penetrate algae to extract carbohydrate product.
Above the algae layer is the cortex. It is a dense layer of fungi cells. But it automatically balances its density in order to filter down sufficient sunlight for the algae.
Cortex density regulated with a negative feedback loop
Lichens are adaptive to different moisture levels and carry out photosynthesis under various circumstances. So how do they do that?
They had developed a passive strategy called poikilohydric, which allows them to regulate their water content following the environment. When the moisture level is high, It can hold the moist within their thallus for as long as possible. When the environment dries up, the lichen will be dry, too, but more slowly. After that, it goes into dormancy and waits for the next humid event.
Passive strategy: Poikilohydry, holds water when wet, dormant when dry.