title: Effects of genetically modified starch metabolism in potato plants on photosynthate fluxes into the rhizosphere and on microbial degraders of root exudates.
abstract: A high percentage of photosynthetically assimilated carbon is released into soil via root exudates, which are acknowledged as the most important factor for the development of microbial rhizosphere communities. As quality and quantity of root exudates are dependent on plant genotype, the genetic engineering of plants might also influence carbon partitioning within the plant and thus microbial rhizosphere community structure. In this study, the carbon allocation patterns within the plant-rhizosphere system of a genetically modified amylopectin-accumulating potato line (Solanum tuberosum L.) were linked to microbial degraders of root exudates under greenhouse conditions, using (13)C-CO(2) pulse-chase labelling in combination with phospholipid fatty acid (PLFA) analysis. In addition, GM plants were compared with the parental cultivar as well as a second potato cultivar obtained by classical breeding. Rhizosphere samples were obtained during young leaf developmental and flowering stages. (13)C allocation in aboveground plant biomass, water-extractable organic carbon, microbial biomass carbon and PLFA as well as the microbial community structure in the rhizosphere varied significantly between the natural potato cultivars. However, no differences between the GM line and its parental cultivar were observed. Besides the considerable impact of plant cultivar, the plant developmental stage affected carbon partitioning via the plant into the rhizosphere and, subsequently, microbial communities involved in the transformation of root exudates.
authors.affiliation: Department of Terrestrial Ecogenetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Soil Ecology, Neuherberg, Germany. silvia.gschwendtner@helmholtzmuenchen.de
authors.forename: Silvia
authors.initials: S
authors.lastname: Gschwendtner
authors.forename: Jürgen
authors.initials: J
authors.lastname: Esperschütz
authors.forename: Franz
authors.initials: F
authors.lastname: Buegger
authors.forename: Michael
authors.initials: M
authors.lastname: Reichmann
authors.forename: Martin
authors.initials: M
authors.lastname: Müller
authors.forename: Jean Charles
authors.initials: JC
authors.lastname: Munch
authors.forename: Michael
authors.initials: M
authors.lastname: Schloter
mesh_terms: D000687:Amylopectin / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism*; D018533:Biomass; D050260:Carbohydrate Metabolism; D002244:Carbon / Q000032:analysis; D002247:Carbon Isotopes / Q000032:analysis; D018556:Crops, Agricultural / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis; D010743:Phospholipids / Q000032:analysis; D053147:Plant Exudates / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D058441:Rhizosphere; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology; D011198:Solanum tuberosum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D005227:Fatty Acids; D010743:Phospholipids; D053147:Plant Exudates; D012987:Soil; D002244:Carbon; D000687:Amylopectin