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Increased trehalose biosynthesis in Hartig net hyphae of ectomycorrhizas
Author(s) -
López Mónica Fajardo,
Männer Philipp,
Willmann Anita,
Hampp Rüdiger,
Nehls Uwe
Publication year - 2007
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2007.01983.x
Subject(s) - trehalose , hypha , biology , biochemistry , biosynthesis , mycelium , fungus , symbiosis , botany , gene , bacteria , genetics
Summary• To obtain photoassimilates in ectomycorrhizal symbiosis, the fungus has to create a strong sink, for example, by conversion of plant‐derived hexoses into fungus‐specific compounds. Trehalose is present in large quantities in Amanita muscaria and may thus constitute an important carbon sink. • In Amanita muscaria –poplar ( Populus tremula × tremuloides ) ectomycorrhizas, the transcript abundances of genes encoding key enzymes of fungal trehalose biosynthesis, namely trehalose‐6‐phosphate synthase ( TPS ), trehalose‐6‐phosphate phosphatase ( TPP ) and trehalose phosphorylase ( TP ), were increased. • When mycorrhizas were separated into mantle and Hartig net, TPS , TPP and TP expression was specifically enhanced in Hartig net hyphae. Compared with the extraradical mycelium, TPS and TPP expression was only slightly increased in the fungal sheath, while the increase in the expression of TP was more pronounced. TPS enzyme activity was also elevated in Hartig net hyphae, displaying a direct correlation between transcript abundance and turnover rate. In accordance with enhanced gene expression and TPS activity, trehalose content was 2.7 times higher in the Hartig net. • The enhanced trehalose biosynthesis at the plant–fungus interface indicates that trehalose is a relevant carbohydrate sink in symbiosis. As sugar and nitrogen supply affected gene expression only slightly, the strongly increased expression of the investigated genes in mycorrhizas is presumably developmentally regulated.