Exudation (plant)

Exudation ( Latin exudare , German “sweat out, drain” , English exudation ), sometimes also root exudation , in plant physiology, in some cases describes the excretion of substances from a plant; the material released is called exudate . The term is not common for all excretion and secretion processes.

In ecology in particular , the term exudation is used for the diffusive excretion of monosaccharides , amino acids and other small-molecule organic compounds. The phytoplankton organisms exude up to half of the photosynthetically formed compounds and thus influence the water surrounding them. In higher plants , such substances are released into the environment via the roots , making them part of the rhizodeposition . They develop various effects in the rhizosphere , so they can allelopathically affect neighboring plants , be used by microorganisms , etc.

In addition, gums that emerge from injuries to the bark and other parts of the plant are also called exudates.

Plant roots excrete, depending on their type and concentration, the type of plant, the age and the development and nutritional status of the plant as well as the soil and environmental conditions, a myriad of substances that are present in the plant: various types of sugar, amino acids, organic acids, proteins , Growth substances, growth inhibitors and others. The exudates serve as food for the microfauna living in the rhizosphere ; the plants benefit in symbiosis from the excretions of these animals, microbes and bacteria, for example from the nitrogen-fixing nodule bacteria .

Every 20: In exudates were found amino acids , 21 organic acids and inorganic acids, 15 , lignin components, 11 sugars 6, allomones (neurotransmitters), 5 glucosinolates , 4 fatty acids and various phenols and mucilage, proteins and enzymes. The root hairs secrete the enzyme phytase , which converts phosphorus- phytate complexes into easily soluble inorganic phosphorus compounds.

Web links

Wiktionary: Exudation  - explanations of meanings, word origins, synonyms, translations

• Root exudates ; private website of the late agricultural journalist Rainer Maché
• Erwin Lengauer: The activity of microbes on plant roots , Research Center for Mountain Agriculture, University of Innsbruck , PDF file

Individual evidence

1. ^ Matthias Schaefer: Dictionary of Ecology . 5, revised and expanded edition. Spektrum Akademischer Verlag, Heidelberg 2012, ISBN 978-3-8274-2562-1 , keyword exudation , p. 87 ( limited preview in Google Book Search - electronic resource).
2. ↑ Schaefer 2012, keyword Phykosphere , p. 223
3. ↑ Gerhard Eisenbrand, Peter Schreier (ed.): Römpp-Lexikon Lebensmittelchemie . Food law edited by Alfred Hagen Meyer. 2nd, completely revised and enlarged edition. Thieme, Stuttgart 2006, ISBN 3-13-143462-7 , keyword rubber , p. 479 ( limited preview in Google Book search).
4. ↑ Erwin Lengauer: The activity of microbes on plant roots , Research Center for Mountain Agriculture, University of Innsbruck , PDF file
5. ↑ Root exudates