title: Functional characterization of LePT4: a phosphate transporter in tomato with mycorrhiza-enhanced expression.
abstract: Many plant roots acquire inorganic phosphate (Pi) from soils directly through the root-soil interface via high-affinity Pi transporters and/or through symbiotic associations between the cortical cells and arbuscular mycorrhizal fungi. In tomato, three phosphate transporters (LePT3, LePT4, and LePT5) are up-regulated upon colonization by arbuscular mycorrhizal fungi. In this study, the role of LePT4 in tomato is elucidated by molecular and physiological characterizations of a loss-of-function mutant lept4. In the absence of mycorrhizal infection and under solution-Pi concentrations (Cp) of 0.05 mM and 0.5 mM, the mutant exhibited severe Pi-deficiency symptoms which were associated with significantly lower Pi uptake as compared with that of the wild type. However, at a Cp of 5 mM, lept4 grew better than the wild type. Mycorrhizal infection at a Cp of 0.05 mM resulted in a significant increase in the transcripts of LePT4 in the wild type and a concomitant 2-fold increase in Pi uptake. Although upon mycorrhizal infection, lept4 also exhibited an increased Pi uptake, it was significantly lower than that of the wild type. Under a Cp of 1 mM and in the absence of mycorrhizal infection, LePT4 expression was suppressed in the wild type and a mutation in this gene resulted in a slight reduction in total Pi uptake. These data highlight the pivotal role of LePT4 in mycorrhizal-mediated Pi uptake in tomato, and show that this function may not be fully compensated by other members of the family. Characterization of the mycorrhiza-associated Pi transporter lept4 mutant, along with expression analysis of LePT3, provides evidence for the different routes of mycorrhiza-mediated Pi uptake in plants.
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China.
authors.forename: Guo-Hua
authors.initials: GH
authors.lastname: Xu
authors.forename: Veronique
authors.initials: V
authors.lastname: Chague
authors.forename: Cathy
authors.initials: C
authors.lastname: Melamed-Bessudo
authors.forename: Yoram
authors.initials: Y
authors.lastname: Kapulnik
authors.forename: Ajay
authors.initials: A
authors.lastname: Jain
authors.forename: Kashchandra G
authors.initials: KG
authors.lastname: Raghothama
authors.forename: Avraham A
authors.initials: AA
authors.lastname: Levy
authors.forename: Avner
authors.initials: A
authors.lastname: Silber
mesh_terms: D001692:Biological Transport / Q000235:genetics; D018527:Hydroponics; D018551:Solanum lycopersicum / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology; D038821:Mycorrhizae / Q000502:physiology*; D028061:Phosphate Transport Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010710:Phosphates / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology; D018520:Plant Shoots / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology
chemical_list: D028061:Phosphate Transport Proteins; D010710:Phosphates; D010940:Plant Proteins