Ectomycorrhizal fungi enhance nitrogen and phosphorus nutrition of Nothofagus dombeyi under drought conditions by regulating assimilative enzyme activities
- 10 July 2009
- journal article
- Published by Wiley in Physiologia Plantarum
- Vol. 136 (4), 426-436
- https://doi.org/10.1111/j.1399-3054.2009.01237.x
Abstract
Drought stress conditions (DC) reduce plant growth and nutrition, restraining the sustainable reestablishment of Nothofagus dombeyi in temperate south Chilean forest ecosystems. Ectomycorrhizal symbioses have been documented to enhance plant nitrogen (N) and phosphorus (P) uptake under drought, but the regulation of involved assimilative enzymes remains unclear. We studied 1-year-old N. dombeyi (Mirb.) Oerst. plants in association with the ectomycorrhizal fungi Pisolithus tinctorius (Pers.) Coker & Couch. and Descolea antartica Sing. In greenhouse experiments, shoot and root dry weights, mycorrhizal colonization, foliar N and P concentrations, and root enzyme activities [glutamate synthase (glutamine oxoglutarate aminotransferase (GOGAT), EC 1.4.1.13-14), glutamine synthetase (GS, EC 6.3.1.2), glutamate dehydrogenase (GDH, EC 1.4.1.2-4), nitrate reductase (NR, EC 1.6.6.1), and acid phosphomonoesterase (PME, EC 3.1.3.1-2)] were determined as a function of soil-water content. Inoculation of N. dombeyi with P. tinctorius and D. antartica significantly stimulated plant growth and increased plant foliar N and P concentrations, especially under DC. Ectomycorrhizal inoculation increased the activity of all studied enzymes relative to non-mycorrhizal plants under drought. We speculate that GDH is a key enzyme involved in the enhancement of ectomycorrhizal carbon (C) availability by fuelling the tricarboxylic acid (TCA) cycle under conditions of drought-induced carbon deficit. All studied assimilative enzymes of the ectomycorrhizal associations, involved in C, N, and P transfers, are closely interlinked and interdependent. The up-regulation of assimilative enzyme activities by ectomycorrhizal fungal root colonizers acts as a functional mechanism to increase seedling endurance to drought. We insist upon incorporating ectomycorrhizal inoculation in existing Chilean afforestation programs.Keywords
This publication has 57 references indexed in Scilit:
- Phosphorus fractions and phosphatase activity in an Andisol under different forest ecosystemsGeoderma, 2008
- Plant limiting nutrients in Andean-Patagonian woody species: Effects of interannual rainfall variation, soil fertility and mycorrhizal infectionForest Ecology and Management, 2008
- The Isoenzyme 7 of Tobacco NAD(H)-Dependent Glutamate Dehydrogenase Exhibits High Deaminating and Low Aminating Activities in VivoPlant Physiology, 2007
- Water transfer via ectomycorrhizal fungal hyphae to conifer seedlingsMycorrhiza, 2007
- Glutamate dehydrogenase in plants: is there a new story for an old enzyme?Plant Physiology and Biochemistry, 2003
- Ectomycorrhizal colonisation of roots and ash granules in a spruce forest treated with granulated wood ashForest Ecology and Management, 2002
- Exploration types of ectomycorrhizaeMycorrhiza, 2001
- Water relations, drought and vesicular-arbuscular mycorrhizal symbiosisMycorrhiza, 2001
- NITRATE REDUCTASE STRUCTURE, FUNCTION AND REGULATION: Bridging the Gap between Biochemistry and PhysiologyAnnual Review of Plant Physiology and Plant Molecular Biology, 1999
- Effect of organic and inorganic nitrogen sources on endogenous polyamines and growth of ectomycorrhizal fungi in pure cultureMycorrhiza, 1999