Ayadi Amal, David Pascale, Arrighi Jean-François, Chiarenza Serge, Thibaud Marie-Christine, Nussaume Laurent, Marin Elena
Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Environnementale et de Biotechnologie, Laboratoire de Biologie du Développement des Plantes, F-13108 Saint-Paul-lez-Durance, France (A.A., P.D., S.C., M.-C.T., L.N., E.M.);Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7265 Biologie Végétale and Microbiologie Environnementale, F-13108 Saint-Paul-lez-Durance, France (A.A., P.D., S.C., M.-C.T., L.N., E.M.); Aix-Marseille Université, F-13108 Saint-Paul-lez-Durance, France (A.A., P.D., S.C., M.-C.T., L.N., E.M.); andLaboratoire des Symbioses Tropicales et Méditerranéennes, TA A-82/J Campus International de Baillarguet, 34398 Montpellier cedex 5, France (J.-F.A.).
Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Environnementale et de Biotechnologie, Laboratoire de Biologie du Développement des Plantes, F-13108 Saint-Paul-lez-Durance, France (A.A., P.D., S.C., M.-C.T., L.N., E.M.);Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7265 Biologie Végétale and Microbiologie Environnementale, F-13108 Saint-Paul-lez-Durance, France (A.A., P.D., S.C., M.-C.T., L.N., E.M.); Aix-Marseille Université, F-13108 Saint-Paul-lez-Durance, France (A.A., P.D., S.C., M.-C.T., L.N., E.M.); andLaboratoire des Symbioses Tropicales et Méditerranéennes, TA A-82/J Campus International de Baillarguet, 34398 Montpellier cedex 5, France (J.-F.A.)
Plant Physiol. 2015 Apr;167(4):1511-26. doi: 10.1104/pp.114.252338. Epub 2015 Feb 10.
Arabidopsis (Arabidopsis thaliana) absorbs inorganic phosphate (Pi) from the soil through an active transport process mediated by the nine members of the PHOSPHATE TRANSPORTER1 (PHT1) family. These proteins share a high level of similarity (greater than 61%), with overlapping expression patterns. The resulting genetic and functional redundancy prevents the analysis of their specific roles. To overcome this difficulty, our approach combined several mutations with gene silencing to inactivate multiple members of the PHT1 family, including a cluster of genes localized on chromosome 5 (PHT1;1, PHT1;2, and PHT1;3). Physiological analyses of these lines established that these three genes, along with PHT1;4, are the main contributors to Pi uptake. Furthermore, PHT1;1 plays an important role in translocation from roots to leaves in high phosphate conditions. These genetic tools also revealed that some PHT1 transporters likely exhibit a dual affinity for phosphate, suggesting that their activity is posttranslationally controlled. These lines display significant phosphate deficiency-related phenotypes (e.g. biomass and yield) due to a massive (80%-96%) reduction in phosphate uptake activities. These defects limited the amount of internal Pi pool, inducing compensatory mechanisms triggered by the systemic Pi starvation response. Such reactions have been uncoupled from PHT1 activity, suggesting that systemic Pi sensing is most probably acting downstream of PHT1.
拟南芥（Arabidopsis thaliana）通过由磷酸盐转运蛋白1（PHT1）家族的九个成员介导的主动运输过程从土壤中吸收无机磷酸盐（Pi）。这些蛋白质具有高度的相似性（大于61%），且表达模式重叠。由此产生的遗传和功能冗余阻碍了对其特定作用的分析。为了克服这一困难，我们的方法是将多个突变与基因沉默相结合，以使PHT1家族的多个成员失活，包括位于5号染色体上的一组基因（PHT1;1、PHT1;2和PHT1;3）。对这些株系的生理分析表明，这三个基因与PHT1;4一起，是Pi吸收的主要贡献者。此外，PHT1;1在高磷条件下从根向叶的转运中起重要作用。这些遗传工具还表明，一些PHT1转运蛋白可能对磷酸盐表现出双重亲和力，这表明它们的活性受到翻译后调控。由于磷酸盐吸收活性大幅降低（80%-96%），这些株系表现出与磷酸盐缺乏相关的显著表型（如生物量和产量）。这些缺陷限制了内部Pi库的数量，诱导了由系统性Pi饥饿反应触发的补偿机制。这些反应与PHT1活性无关，这表明系统性Pi感知很可能在PHT1的下游起作用。
