Endophyte
As endophytes (from ancient Greek ἔνδον éndon "inside, inside" and φυτόν phytón "growth, plant") are living beings, usually fungi or bacteria , which live inside the vegetation of a plant . While some endophytes cause symptoms of disease, others do not cause damage and can even have a symbiotic relationship with their host plant by producing substances that promote the growth of the plant or increase its stress tolerance . It is assumed that these mutually beneficial cases arose from the coevolution of host and colonist from an originally parasitic relationship.
Endophytic fungi
Endophytic fungi in the Epichloë genus (and anamorphic relatives of the Neotyphodium genus ) often colonize grasses in which the fungal mycelium can penetrate the entire stem and the leaves. After infection of the flowers, these fungi are often spread with the seeds of their host plant. For neotyphodium this is the only form of reproduction and distribution. Infections from neighboring plants only occur in the case of Epichloë . These endophytic fungi often produce alkaloids , which protect plants and fungi from predators. In addition, colonization with the fungus can make the host plant more robust against environmental factors such as drought, although the underlying mechanisms of this protection are still largely unknown.
A well-known example is the reed fescue ( Festuca arundinacea ), which is colonized by the tubular fungus Neotyphodium coenophialum . While uninfected grass makes good pasture forage, livestock that eat infected grass display a range of symptoms ranging from lethargy to decreased growth and reduced fertility to gangrene . The ergot alkaloids produced by N. coenophialum , especially ergovalin , are responsible for these symptoms . Other alkaloids produced by N. coenophialum , in particular loline alkaloids and peramine, have insecticidal properties, so that they help protect the grass endophyte community from eating.
Possible applications for endophytic fungi, which are being researched, are the use to generate increased tolerance in crops to insect damage and drought, if possible with the plant being suitable for animal feed.
Numerous root-colonizing mycorrhizal fungi also grow at least partially inside the plant body and thus endophytically . These are found as symbionts in most land plants and have a positive influence on the nutrient uptake and stress tolerance of their hosts. However, they are usually not referred to as endophytes, since a significant part of the mycelium grows outside the plant body.
Endophytic bacteria
Different types of endophytic bacteria have been detected in several plants. Different types of bacteria can be found in the same plant at the same time, whereby individual types usually colonize a certain plant tissue.
In addition to pathogenic bacteria such as Agrobacterium tumefaciens , many endophytic bacteria do not cause any symptoms of disease or even lead to growth-promoting effects. Various species are known that produce plant hormones that can influence growth. The provision of nutrients by endophytic bacteria is also of great importance, in particular the fixation of nitrogen from the air, most developed in the symbiosis between nodule bacteria and legumes . In some cases, it has also been shown that colonization with endophytic bacteria made the host plant more resistant to attack by pathogens , possibly because the endophytes were already occupied with possible attack sites or by producing antibodies.
Endophytic Kinetoplastea
The Kinetoplastea (also Kinetoplastida) form a class of flagellated unicellular organisms ( flagellates ); they belong to the Euglenozoa . Many kinetoplasts are parasites . The Trypanosomatida are a group of unicellular flagellates within the group of the Kinetoplastea; ( African sleeping sickness and various animal diseases are caused by the associated species). Some plant pests of the genus Phytomonas belong to these Trypanosomatida.
Endophytic algae
Marine macroalgae are commonly inhabited by endophytic filamentous brown , red, and green algae . The endophytes often grow entirely within the host, only the reproductive structures of the endophytes are on the host surface. Endophytic filamentous brown algae, with the exception of Herpodiscus durvillaeae, are pigmented and therefore do not depend on a host to provide them with nutrients. The majority of endophytic red algae, on the other hand, have reduced pigmentation or have completely lost it and are therefore necessarily dependent on the host.
Endophytic algae infections often occur together with morphological malformations in marine macroalgae. However, a causal relationship between endophyte infections and symptoms has not yet been established.
See also
literature
- Peter H. Raven, Ray F. Evert, Susan E. Eichhorn: Biology of plants . Walter de Gruyter, Berlin / New York 2000, ISBN 3-11-015462-5 .
- S. Aldrich-Markham, G. Pirelli, AM Craig: Endophyte Toxins in Grass Seed Fields and Straw - Effects on Livestock. Extension Service, Oregon State University, 1995/2007. (PDF)
- Cindy Lodewyckx, Jaco Vangronsveld, Fiona Porteous, Edward RB Moore, Safieh Taghavi, Max Mezgeay, Daniel van der Lelie: Endophytic Bacteria and Their Potential Applications . In: Critical Reviews in Plant Sciences . No. 21 (6) , 2002, pp. 583-606 .
Web links
- Renate U. Vanselow: Loss of Biodiversity: Overlooked Fungal Regulators.
Individual evidence
- ^ A b K. Clay, C. Schardl: Evolutionary origins and ecological consequences of endophyte symbiosis with grasses . In: American Naturalist . Vol. 160, Suppl 4, February 2002, pp. S99-S127 , PMID 18707456 .
- ^ AF Peters: Field and culture studies of Streblonema macrocystis sp. nov. (Ectocapales, Phaeophyceae) from Chile, a sexual endophyte of giant kelp . In: Phycologia . tape 30 , no. 4 , July 1991, ISSN 0031-8884 , pp. 365–377 , doi : 10.2216 / i0031-8884-30-4-365.1 ( tandfonline.com [accessed March 17, 2019]).
- ↑ Akira F. Peters: Taxonomic implications of gamete fusions in the parasitic brown alga Herpodiscus durvillaeae . In: Canadian Journal of Botany . tape 68 , no. 6 , June 1990, ISSN 0008-4026 , pp. 1398–1401 , doi : 10.1139 / b90-178 ( nrcresearchpress.com [accessed March 17, 2019]).
- ^ JA Callow, ME Callow, LV Evans: Nutritional Studies on the Parasitic Red Alga Choreocolax polysiphoniae . In: The New Phytologist . tape 83 , no. 2 , 1979, ISSN 0028-646X , pp. 451-462 , JSTOR : 2434145 .
- ↑ Miriam S. Bernard, Martina Strittmatter, Pedro Murúa, Svenja Heesch, Ga Youn Cho: Diversity, biogeography and host specificity of kelp endophytes with a focus on the genera Laminarionema and Laminariocolax (Ectocarpales, Phaeophyceae) . In: European Journal of Phycology . tape 54 , no. 1 , January 2, 2019, ISSN 0967-0262 , p. 39–51 , doi : 10.1080 / 09670262.2018.1502816 .