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Poster De Conférence Année : 2016

Functional PTB phosphate transporters are present in streptophyte algae and early diverging land plant

C. Bonnot
Holger Breuninger
Alexander Hetherington
Steven Kelly
Liam Dolan

Résumé

Plants absorb orthophosphate (Pi) through Pi-transporter proteins located in the plasma membrane of cells at the interface with the external environment. PHOSPHATE TRANSPORTER 1 (PHT1) proteins transport Pi through H+/Pi-co- transport across the plasma membrane of root cells in angiosperms. The presence of PHT1 genes in early diverging land plants and streptophyte algae suggests that PHT1 protein function in all streptophyte lineages. However, Pi- uptake depend on Na+-influx in streptophyte algae implying that Na+/Pi- symporters function at the plasma membrane of streptophytes. Here we report 26 the discovery of PHOSPHATE TRANSPORTER B (PTB) in streptophyte algae and land plants. Previously identified in chlorophyte algae only, the PTB proteins are hypothesised to uptake Pi by Na+/Pi-symport. Consistent with a role in Pi- uptake from the environment, streptophyte PTB proteins are predicted to be plasma membrane proteins and the steady state levels of mRNAs of most PTB genes in the bryophyte Marchantia polymorpha and in the streptophyte alga Coleochaete nitellarum are higher low-Pi than in replete-Pi environments and in M. polymorpha rhizoids than in M. polymorpha thallus. The expression of M. polymorpha PTB proteins in the Saccharomyces cerevisiae pho2 mutant, defective in high-affinity Pi-transport, rescues growth in low-Pi environments. These data demonstrate that PTB proteins are plasma membrane Pi- transporters and suggest that PTB and PHT1 proteins operate in parallel in early diverging land plants and streptophyte algae. This dual system might attest the progressive transition between two Pi-uptake mechanisms and adaptation to dry habitat during land colonization.
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hal-04187819 , version 1 (25-08-2023)

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  • HAL Id : hal-04187819 , version 1

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C. Bonnot, Hélène Proust, Benoît Pinson, Florine P L Colbalchini, Alexis Lesly-Veillard, et al.. Functional PTB phosphate transporters are present in streptophyte algae and early diverging land plant. EMBO Workshop on New model systems for early land plant evolution, Jun 2016, Vienne, Austria. . ⟨hal-04187819⟩

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