Photochemical processes, carbon assimilation and RNA accumulation of sucrose transporter genes in tomato arbuscular mycorrhiza |
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Authors: | Boldt Katja Pörs Yvonne Haupt Bastian Bitterlich Michael Kühn Christina Grimm Bernhard Franken Philipp |
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Institution: | a Leibniz-Institute of Vegetable and Ornamental Crops, Theodor-Echtermeyer-Weg 1, D-14979 Grossbeeren, Germany b Humboldt University, Institute of Biology, Plant Physiology, Philippstrasse 13, D-10115 Berlin, Germany c Humboldt University, Institute of Biology, Cell Biology, Invalidenstrasse 42, D-10115 Berlin, Germany |
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Abstract: | Arbuscular mycorrhizal fungi enhance CO2 assimilation of their hosts which ensure the demand for carbohydrates of these obligate biotrophic microorganisms. Photosynthetic parameters were measured in tomato colonised or not by the arbuscular mycorrhizal fungus Glomus mosseae. In addition, carbohydrate contents and mRNA accumulation of three sucrose transporter genes were analysed. Mycorrhizal plants showed increased opening of stomata and assimilated significant more CO2. A higher proportion of the absorbed light was used for photochemical processes, while non-photochemical quenching and the content of photoprotective pigments were lower. Analysis of sugar contents showed no significant differences in leaves but enhanced levels of sucrose and fructose in roots, while glucose amounts stayed constant. The three sucrose transporter encoding genes of tomato SlSUT1, SlSUT2 and SlSUT4 were up-regulated providing transport capacities to transfer sucrose into the roots. It is proposed that a significant proportion of sugars is used by the mycorrhizal fungus, because only amounts of fructose were increased, while levels of glucose, which is mainly transferred towards the fungus, were nearly constant. |
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Keywords: | A/ci CO2 uptake rate in relation to intercellular CO2 concentration AM arbuscular mycorrhiza C mock-inoculated ci intercellular CO2 concentration JCO2 CO2 uptake rate PPFD photosynthetic photon flux density PSII photosystem II SUT sucrose transporters ΦPSII apparent quantum yield of PSII photochemistry |
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