Leaf phosphorus fractionation in rice to understand internal phosphorus-use efficiency

Area of Science:

• Plant Physiology
• Agricultural Science
• Biochemistry

Background:

• Phosphorus (P) availability is a major constraint for rice (Oryza sativa) production, impacting sustainable agriculture.
• Improving internal phosphorus use efficiency (PUE) is critical, especially in low-input farming systems.
• Understanding how leaf P is allocated to different chemical fractions is key to PUE but remains poorly understood.

Purpose of the Study:

• To investigate the influence of key phosphorus (P) fractions on PUE in rice.
• To identify specific P fractions that can be targeted to enhance PUE in rice genotypes.

Main Methods:

• Cultivation of three high-PUE and two low-PUE rice genotypes in hydroponics under varying P supplies.
• Measurement of phosphorus use efficiency (PUE), total P, P fractions, photosynthetic rates, and biomass.
• Analysis of P allocation across different chemical fractions (nucleic acid-P, lipid-P, inorganic-P, metabolite-P, residual-P).

Main Results:

• Low investment in lipid-P was strongly correlated with increased photosynthetic PUE (PPUE), achieved by lowering total leaf P concentration.
• Plants grown with low P supply showed reduced investment in inorganic-P and lipid-P, but not nucleic acid-P.
• Whole-plant PUE was associated with reduced total P concentration, enhanced biomass, and preferential resource allocation to younger leaves.

Conclusions:

• Reduced investment in lipid-P improves PUE in rice without negatively impacting photosynthesis, a novel finding.
• Targeting rice varieties with lower lipid-P investment presents a new strategy for enhancing PUE.
• This research can benefit rice production in P-deficient soils and reduce reliance on P fertilizers, contributing to global food security.