Key words
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citrate; malate; phosphorus; potato; root-soil interface; transport
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Research programs
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COST-Action 631 - Understanding and Modelling Plant - Soil Interactions in the Rhizosphere Environment
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Short description
(English)
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Serveral transgenic plants have been generated in the applicant's lab in the past few years which serve as model systems to test the hypothesis that acquisition of P, one of the most limiting elements in plant nutrition, affects uptake and accumulation of other nutrient elements, especially those, which are critical for human nutrition, i.e. Fe, Zn, and Ca. The different transgenic plants proposed in this project express heterologous genes such as phytase or citrate synthase, a phosphate transporters or a malate exporter, respectively. Additionally, mutant Petunia plants will be identified which overaccumulate the nutrients specified above. All these plant species will be analyzed on a molecular physiological level in absence and presence of the arbuscular mycorrhizal symbiosis with respect to gene expression, rhizosecretion, and acquisition and translocation of nutrient elements. This project could eventually reveal mechanisms which could be used to generate healthier plants, with respect to plant tolerance to low P conditions, but also whith respect to human nutrition or clean-up of contaminated soils.
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Partners and International Organizations
(English)
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AT, BE, BG, CH, CY, CZ, DE, DK, ES, FI, FR, GR, HU, IL, IT, NL, NO, PL, SE, SI, SK, UK
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Abstract
(English)
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Dinitrogen fixation symbioses, like the rhizobial and the actinorhizal symbiosis, respectively, are based on the exchange of photosynthetic carbon and of nitrogen between the two symbionts. The gene product AgDCAT1 from alder (Alnus glutinosa L. Gaertner) was recently shown to be localized at the root-Frankia symbiotic interface in actinorhizal nodules, and to mediate dicarboxylate uptake in yeast and E. coli cells, respectively. Although experimental evidence for export activity of AgDCAT1 was missing, the protein was proposed to be involved in malate export from the plant host to the Frankia microsymbiont in nodules of actinorhizal roots. In this project, we showed that the AgDCAT1 gene confers enhanced exudation of di- and tricarboxylic acids at the root-soil interface of transgenic potato (Solanum tuberosum L. var. Solara) when expressed under the control of a root hair cell (= trichoblast)-specific promoter. This is clear evidence for AgDCAT1 acting as an exporter in planta which, in combination with data from Jeong et al. (200), identifies AgDCAT1 as the first plant plasma membrane transporter involved in exchange of carbon with the microbial partner in a root symbiosis. Expression of AgDCAT1 in root hair cells led to enhanded secretion of organic acids from roots and increased plant P uptake efficiency and Al tolerance. This trait could thus be of major importance in root biotechnology for crop improvement.
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References in databases
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Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. +41 31 322 74 82 Swiss Project-Number: C02.0081
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