TY - JOUR
T1 - Overexpression of PSR1 in Chlamydomonas reinhardtii induces luxury phosphorus uptake
AU - Slocombe, Stephen p.
AU - Zúñiga-Burgos, Tatiana
AU - Chu, Lili
AU - Mehrshahi, Payam
AU - Davey, Matthew p.
AU - Smith, Alison g.
AU - Camargo-Valero, Miller alonso
AU - Baker, Alison
N1 - © 2023 Slocombe, Zúñiga-Burgos, Chu, Mehrshahi, Davey, Smith, Camargo-Valero and Baker. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY
PY - 2023/7/27
Y1 - 2023/7/27
N2 - Remediation using micro-algae offers an attractive solution to environmental phosphate (PO43-) pollution. However, for maximum efficiency, pre-conditioning of algae to induce ‘luxury phosphorus (P) uptake’ is needed. To replicate this process, we targeted the global regulator PSR1 (Myb transcription factor: Phosphate Starvation Response 1) for over-expression in algae. Manipulating a single gene (PSR1) drove uptake of both PO43- and a Mg2+ counter-ion leading to increased PolyP granule size, raising P levels 4-fold to 8% dry cell weight, and accelerated removal of PO43- from the medium. Examination of the gene expression profile showed that the P-starvation response was mimicked under P-replete conditions, switching on luxury uptake. Hyper-accumulation of P depended on a feed-forward mechanism, where a small set of ‘Class I’ P-transporter genes were activated despite abundant external PO43- levels. The transporters drove a reduction in external PO43- levels, permitting more genes to be expressed (Class II), leading to more P-uptake. Our data pointed toward a PSR1-independent mechanism for detection of external PO43- which suppressed Class II genes. This model provided a plausible mechanism for P-overplus where prior P-starvation elevates PSR1 and on P-resupply causes luxury P-uptake. This is because the Class I genes, which include P-transporter genes, are not suppressed by the excess PO43-. Taken together, these discoveries facilitate a bio-circular approach of recycling nutrients from wastewater back to agriculture.
AB - Remediation using micro-algae offers an attractive solution to environmental phosphate (PO43-) pollution. However, for maximum efficiency, pre-conditioning of algae to induce ‘luxury phosphorus (P) uptake’ is needed. To replicate this process, we targeted the global regulator PSR1 (Myb transcription factor: Phosphate Starvation Response 1) for over-expression in algae. Manipulating a single gene (PSR1) drove uptake of both PO43- and a Mg2+ counter-ion leading to increased PolyP granule size, raising P levels 4-fold to 8% dry cell weight, and accelerated removal of PO43- from the medium. Examination of the gene expression profile showed that the P-starvation response was mimicked under P-replete conditions, switching on luxury uptake. Hyper-accumulation of P depended on a feed-forward mechanism, where a small set of ‘Class I’ P-transporter genes were activated despite abundant external PO43- levels. The transporters drove a reduction in external PO43- levels, permitting more genes to be expressed (Class II), leading to more P-uptake. Our data pointed toward a PSR1-independent mechanism for detection of external PO43- which suppressed Class II genes. This model provided a plausible mechanism for P-overplus where prior P-starvation elevates PSR1 and on P-resupply causes luxury P-uptake. This is because the Class I genes, which include P-transporter genes, are not suppressed by the excess PO43-. Taken together, these discoveries facilitate a bio-circular approach of recycling nutrients from wastewater back to agriculture.
KW - biomass
KW - micro-algae
KW - polyphosphate
KW - transcription factor
KW - waste water remediation
U2 - 10.3389/fpls.2023.1208168
DO - 10.3389/fpls.2023.1208168
M3 - Article
VL - 14
JO - Frontiers in Plant Science
JF - Frontiers in Plant Science
M1 - 1208168
ER -
