Proteoid roots
Proteoid roots are densely packed roots that are formed by some plants when there is a lack of phosphate in order to improve phosphate uptake.
Proteoid get their name from the family of the Proteaceae , where this phenomenon was first observed. This family grows on the very low phosphorus soils of Australia. In contrast to most other plants, the roots are formed close together in a small volume of soil. Due to the formation of large amounts of organic acids (mostly citric acid ), which are released into the soil as root exudates, the pH value of the soil solution in this small volume is reduced and the solubility of phosphates is significantly increased. As a result, even the rhizosphere in limestone soils can be acidified, with the poorly soluble calcium phosphate being dissolved and converted into calcium citrate .
In addition to phosphorus, iron , manganese and zinc are also mobilized and made accessible to the plant.
The proteoid roots can make up 80 percent of the total root mass.
In addition to the Proteaceae, proteoid roots also occur in representatives of the Myricaceae , the Casuarinaceae , but also in annual legumes such as the white lupine ( Lupinus albus ). L. albus invests up to 23 percent of its photosynthetic products in the formation of organic acids. If the phosphate supply is sufficient, the proteoid roots are not formed.
literature
used for the article:
- Horst Marschner: Mineral Nutrition of Higher Plants . Second edition, Academic Press, London 1995, pp. 517f. and 556ff. ISBN 0-12-473543-6
further: