TY - JOUR

T1 - Sugar for my honey

T2 - Carbohydrate partitioning in ectomycorrhizal symbiosis

AU - Nehls, Uwe

AU - Grunze, Nina

AU - Willmann, Martin

AU - Reich, Marlis

AU - Küster, Helge

N1 - Funding information: This work was financed by the Deutsche Forschungsgemeinschaft as part of the focus program ”Molecular Biology of Mycorrhiza”. We are indebted to Margaret Ecke and Andrea Bock for excellent technical assistance and to Dr. Mika Tarkka for critical reading of the manuscript.

PY - 2007/1/1

Y1 - 2007/1/1

N2 - Simple, readily utilizable carbohydrates, necessary for growth and maintenance of large numbers of microbes are rare in forest soils. Among other types of mutualistic interactions, the formation of ectomycorrhizas, a symbiosis between tree roots and certain soil fungi, is a way to overcome nutrient and carbohydrate limitations typical for many forest ecosystems. Ectomycorrhiza formation is typical for trees in boreal and temperate forests of the northern hemisphere and alpine regions world-wide. The main function of this symbiosis is the exchange of fungus-derived nutrients for plant-derived carbohydrates, enabling the colonization of mineral nutrient-poor environments. In ectomycorrhizal symbiosis up to 1/3 of plant photoassimilates could be transferred toward the fungal partner. The creation of such a strong sink is directly related to the efficiency of fungal hexose uptake at the plant/fungus interface, a modulated fungal carbohydrate metabolism in the ectomycorrhiza, and the export of carbohydrates towards soil growing hyphae. However, not only the fungus but also the plant partner increase its expression of hexose importer genes at the plant/fungus interface. This increase in hexose uptake capacity of plant roots in combination with an increase in photosynthesis may explain how the plant deals with the growing fungal carbohydrate demand in symbiosis and how it can restrict this loss of carbohydrates under certain conditions to avoid fungal parasitism.

AB - Simple, readily utilizable carbohydrates, necessary for growth and maintenance of large numbers of microbes are rare in forest soils. Among other types of mutualistic interactions, the formation of ectomycorrhizas, a symbiosis between tree roots and certain soil fungi, is a way to overcome nutrient and carbohydrate limitations typical for many forest ecosystems. Ectomycorrhiza formation is typical for trees in boreal and temperate forests of the northern hemisphere and alpine regions world-wide. The main function of this symbiosis is the exchange of fungus-derived nutrients for plant-derived carbohydrates, enabling the colonization of mineral nutrient-poor environments. In ectomycorrhizal symbiosis up to 1/3 of plant photoassimilates could be transferred toward the fungal partner. The creation of such a strong sink is directly related to the efficiency of fungal hexose uptake at the plant/fungus interface, a modulated fungal carbohydrate metabolism in the ectomycorrhiza, and the export of carbohydrates towards soil growing hyphae. However, not only the fungus but also the plant partner increase its expression of hexose importer genes at the plant/fungus interface. This increase in hexose uptake capacity of plant roots in combination with an increase in photosynthesis may explain how the plant deals with the growing fungal carbohydrate demand in symbiosis and how it can restrict this loss of carbohydrates under certain conditions to avoid fungal parasitism.

KW - Amanita

KW - Ectomycorrhiza

KW - Gene expression

KW - Poplar

KW - Sugar regulation

UR - http://www.scopus.com/inward/record.url?scp=33845587069&partnerID=8YFLogxK

U2 - 10.1016/j.phytochem.2006.09.024

DO - 10.1016/j.phytochem.2006.09.024

M3 - Review article

C2 - 17078984

AN - SCOPUS:33845587069

VL - 68

SP - 82

EP - 91

JO - PHYTOCHEMISTRY

JF - PHYTOCHEMISTRY

SN - 0031-9422

IS - 1

ER -