About 90% of all known lichens have a green alga as a symbiont. has single cells that are globose, which is common in lichens. (green alga or cyanobacterium) but its acceptance was slow to develop . The goal of this mini review is to briefly review what is known about the .. defense responses during successful lichen symbiosis (Joneson et al. A lichen is an organism that results from a mutualistic relationship between a The other organism is usually a cyanobacterium or green alga.
How do Lichens Grow? They also provide vitamins to the fungus. Cyanobacteria can make amino acids directly from the nitrogen gas in the atmosphere, something neither fungi nor algae can do. The fungus, in turn, protects its partners from drying out and shades them from strong sunlight by enclosing the photosynthesizing partners within the body of the lichen. This life habit has allowed lichens to successfully colonize many different habitats.
Lichens have a truly remarkable resistance to drought. A dry lichen can quickly absorb from 3 to 35 times its weight in water! Lichens can also absorb moisture from dew or fog, even from the air itself if the humidity is very high and the temperature is low.
They also dry out slowly, making it possible for the photosynthesizing partner s to make food for as long as possible. This ability to quickly absorb and retain water from many sources makes it possible for lichens to live in harsh environments like deserts and polar regions, and on exposed surfaces like bare rocks, roofs and tree branches. The thallus, or lichen body, comes in four shapes: Most lichens grow slowly, probably because they live in environments where water is available for only short periods.
They tend to live for many years, and lichens hundred of years old can be used to date the rock surfaces on which they grow. Lichens spread mostly by small pieces of their body being blown around. All the partners in the original lichen body are present in the fragment, so growth can begin immediately.
Some lichens create soredia, balls of tissue made just for dispersal. Although the fungus is the major partner, dispersal by spores is rare. Uses for Lichens Lichens have many uses.
They differ in their sensitivity to air pollution, and the presence or absence of different lichens in an area has been used to map concentrations of pollutants. Foliose lichens are used to represent trees in model train layouts. Lichens also make about known "secondary products".
It is thought that these chemicals are produced by lichens as defenses against disease and parasites, and, in some cases, to make the lichen taste unpleasant to animals.
Some of these compounds are now used as anti-viral and anti-bacterial medications.
Symbiosis in lichens - Wikipedia
Other secondary products are used to make everyday life more colorful and pleasant. Some are used to scent Wool Dyed with Lichenssoaps and make perfumes. Other lichen fungi occur in only five orders in which all members are engaged in this habit Orders GraphidalesGyalectalesPeltigeralesPertusarialesand Teloschistales.
Lichenized and nonlichenized fungi can even be found in the same genus or species.
Lichens | Herbarium | USU
TrebouxiophyceaePhaeophyceaeChlorophyceae have been found to associate with the lichen-forming fungi. One fungus, for example, can form lichens with a variety of different algae.
The thalli produced by a given fungal symbiont with its differing partners will be similar, and the secondary metabolites identical, indicating that the fungus has the dominant role in determining the morphology of the lichen.
Further, the same algal species can occur in association with different fungal partners. Lichens are known in which there is one fungus associated with two or even three algal species.
Symbiosis in lichens
Rarely, the reverse can occur, and two or more fungal species can interact to form the same lichen. Chlorococcales is now a relatively small order and may no longer include any lichen photobionts.Symbiotic Plants
Algae that resemble members of the Trebouxia are presumed to be in the class Trebouxiophyceae and go by the same descriptive name Trebouxioid. Cyanolichens[ edit ] Although the photobionts are almost always green algae chlorophytasometimes the lichen contains a blue-green alga instead cyanobacterianot really an algaand sometimes both types of photobionts are found in the same lichen.
A cyanolichen is a lichen with a cyanobacterium as its main photosynthetic component photobiont.