The spatial expression patterns of a phosphate transporter (MtPT1) from Medicago truncatula indicate a role in phosphate transport at the root/soil interface

Abstract

SummaryThe movement of phosphate from the soil into plant root cells is the ®rst of many crucial transport events required to supply phosphorous (P) to cells throughout the plant. In addition to the ability to acquire phosphate from the soil, the majority of the vascular plants are able to form arbuscular mycorrhizal associations in which phosphate may be delivered to the cortex via a fungus. Previously, we cloned two phosphate transporter genes, MtPT1 and MtPT2 from Medicago truncatula roots. Complementation of a yeast phosphate transport mutant revealed that MtPT1 is a functional phosphate transporter and Northern analyses revealed that MtPT1 is expressed exclusively in roots (Liu et al., 1998, Mol. Plant-Microbe Interact. 11, 14±22). Utilising an antibody speci®c for MtPT1, we have analysed the accumulation and spatial expression patterns of the MtPT1 transporter. MtPT1 transcript and protein levels show close correlation and increase dramatically in the roots in response to phosphate starvation. MtPT1 protein levels decrease in roots during development of a symbiosis with arbuscular mycorrhizal (AM) fungi, indicating that this transporter is not involved in symbiotic phosphate transport. Membrane fractionation and analysis of a MtPT1/GFP fusion protein revealed that MtPT1 is located in the plasma membrane, while in situ hybridisation and immunolocalisation demonstrate the presence of MtPT1 transcripts and protein in the epidermal cells and root hairs of M. truncatula roots. MtPT1 shows expression patterns consistent with a role speci®cally in the acquisition of phosphate from the soil and is distinct from the other phosphate transporter of this class described to date.

The arbuscular mycorrhizal fungus Glomus mosseae can enhance arsenic tolerance in Medicago truncatula by increasing plant phosphorus status and restricting arsenate uptake

“…Means followed by the same letter within columns are not significantly different by Duncan's multiple range test at the 5% level. downregulate high-affinity phosphate transporters (MtPT1 and MtPT2) which may be responsible for absorption of phosphate from soil by M. truncatula (Liu et al, 1998;Chiou et al, 2001;Burleigh, 2001). Furthermore, studies on the kinetics of phosphate/arsenate uptake have suggested that AMF can downregulate phosphate/arsenate transporters in both arsenate resistant and non-resistant Holcus lanatus (Gonzalez-Chavez et al, 2002).…”

Characterization of Lipid Rafts from Medicago truncatula Root Plasma Membranes: A Proteomic Study Reveals the Presence of a Raft-Associated Redox System

“…The PM was purified essentially according to Rabotti and Zocchi (1994) and Chiou et al (2001). All steps were performed at 4°C.…”

OsPHF1 Regulates the Plasma Membrane Localization of Low- and High-Affinity Inorganic Phosphate Transporters and Determines Inorganic Phosphate Uptake and Translocation in Rice

“…Similar to yeast PHO84, members of the PHT1 family are localized to the plasma membrane (Chiou et al, 2001;Shin et al, 2004). This indicates that the activity of Pi transporters is controlled through the secretory pathway trafficking to the plasma membrane.…”