INFLUENCE OF ADVERSE SOIL CONDITIONS ON FORMATION AND FUNCTION OF ARBUSCULAR MYCORRHIZAL

Authors: Entry, James; RYGIEWICZ, PAUL - US EPA; WATRUD, LIDIA - US EPA; DONNELLY, PAULA - SANTA FE COMMUN. COLLEGE

Submitted to: Vesicular Arbuscular Mycorrhizas in Interactions in Plants Rhizosphere and
Publication Type: Book / Chapter
Publication Acceptance Date: 8/20/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Mycorrhizal associations in terrestrial ecosystems influence organic and inorganic nutrient relationships, water relations and carbon cycling in plants. Relatively little is known about factors that control the vigor and extent of mycorrhization. This lack of understanding arises in large part from the difficulty of studying the intact association, which is a functionally and anatomically distinct structure comprised of two biologically different organisms, (e.g., plants and arbuscular mycorrhizae (AM) fungi). Adverse conditions, in one form or another, are a pervasive feature in both natural and agronomic soils. The soil environment is constantly changing with regard to moisture, temperature and nutrition. In addition, soil properties are often changed to improve crop yields and, in many cases, soils may be contaminated through disposal of chemicals that are toxic to plants and microorganisms. The formation and function of mycorrhizal relationships are affected by edaphic conditions such as soil moisture, temperature, and pH. Arbuscular mycorrhizae have the ability to alleviate many anthropogenic derived plant stresses. The efficacy of plant-mycorrhizal associations to remediate soils contaminated with toxic pollutants is an that can directly benefit the public and deserves increased emphasis. Before the full potential benefits of AM fungi to host plants and to the reclamation of soils with adverse physical and chemical conditions can be realized research advances are needed in the axenic culture, genetic development, and physiology of these ubiquitous symbionts.

Technical Abstract: Mycorrhizal associations in terrestrial ecosystems influence organic and inorganic nutrient relationships, water relations and carbon cycling in plants. Relatively little is known about factors that control the vigor and extent of mycorrhization. This lack of understanding arises in large part from the difficulty of studying the intact association, which is a functionally and anatomically distinct structure comprised of two biologically different organisms, (e.g., plants and arbuscular mycorrhizae (AM) fungi). Adverse conditions, in one form or another, are a pervasive feature in both natural and agronomic soils. The soil environment is constantly changing with regard to moisture, temperature and nutrition. In addition, soil properties are often changed to improve crop yields and, in many cases, soils may be contaminated through disposal of chemicals that are toxic to plants and microorganisms. The formation and function of mycorrhizal relationships are affected by edaphic conditions such as soil composition, moisture, temperature, pH, cation exchange capacity and anthropogenic abiotic and biotic stressors including soil compaction, heavy metals and pesticides. The magnitude of stress will be affected by external and internal factors which limit the chemical or physical changes, for example, amount of stress reaching the target and length of exposure. Factors limiting dose include stress avoidance (external) and stress tolerance (internal) mechanisms. In this chapter we review the effects of a number of soil-associated stresses including soil moisture, temperature, pH, heavy metals, agricultural practices and pesticides on AM development and function and on host plant tolerance to these stresses.