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Can Phosphite Substitute for Phosphate in ptxD Rice? Evidence From Uptake and Agronomic Performance
Clenya Carla Leandro de Oliveira1, André Luís da Silva Parente Nogueira1, José Nivaldo de Oliveira Sátiro1
1Institute of Agronomy, Department of Soil Science, Federal Rural University of Rio de Janeiro, Seropédica, Brazil.
Physiologia Plantarum
|June 19, 2026
Summary
Engineered rice can use phosphite (Phi) as a phosphorus source, but its uptake is less efficient than phosphate (Pi). This suggests Phi is a complementary fertilizer, not a phosphate substitute.
Area of Science:
- Agricultural Science
- Plant Biotechnology
- Nutrient Management
Background:
- Engineering crops to utilize phosphite (Phi) as a phosphorus (P) source offers enhanced nutrient use efficiency.
- The ptxD gene enables phosphite metabolism, presenting a potential for innovative crop management strategies.
Purpose of the Study:
- To evaluate the capacity of engineered rice (Oryza sativa L.) to utilize phosphite (Phi) as a phosphorus source.
- To compare the agronomic performance and uptake efficiency of phosphite versus phosphate in transgenic rice.
Main Methods:
- Cultivation of transgenic rice lines expressing a codon-optimized ptxD gene under soil and hydroponic conditions.
- Application of graded doses of phosphate (Pi) or phosphite (Phi) in low-P Ferralsol and controlled hydroponic environments.
- Real-time quantification of Pi and Phi depletion using a fluorometric assay with thermostable phosphite dehydrogenase (17X-PTDH).
Main Results:
- Transgenic rice lines showed enhanced growth and phosphorus accumulation when fertilized with Phi compared to wild-type (WT) plants.
- Agronomic performance with Phi was consistently lower than with Pi, particularly at reduced fertilization doses.
- Uptake kinetics demonstrated slower Phi absorption and restricted biomass accumulation at low Phi concentrations, indicating lower acquisition efficiency than Pi.
Conclusions:
- Engineered rice (Oryza sativa L.) can metabolize phosphite (Phi) as a P source, confirming functional ptxD expression.
- Phosphite acquisition efficiency in engineered rice is substantially inferior to phosphate (Pi) uptake.
- Phosphite should be considered a complementary fertilizer or weed management tool, not a complete phosphate substitute in ptxD-based systems.
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