How can botanists improve rice’s ability to use phosphorus?

Phosphorus (P) availability is often limiting for rice (Oryza sativa) production. It’s used for many biological processes, including genetic control, cell structure and energy transfer. If scientists could improve a plant’s use of phosphorus, it would help boost productivity. Patrick Hayes and colleagues investigated where leaf phosphorus is invested in different chemical ‘fractions’ (nucleic acid-P, lipid-P, inorganic-P, metabolite-P and residual-P). They found that plants could improve their phosphorus use efficiency without affecting photosynthesis by changing where they put their phosphorus.

Phosphorus is one of the most common limiting nutrients for plant productivity. It’s lacking in over half of the world’s agricultural soils and so is frequently added in fertilizer. In their article, Hayes and colleagues write that this is an urgent problem.

“The main source of P fertilizers is non-renewable rock phosphate. However, low-cost safe rock phosphate reserves are expected to be exhausted in the next 50–100 years, driving up future costs of food production and impacting global food security… Furthermore, the irresponsible use of P fertilizer leads to P loss via run-off, causing off-site environmental problems such as eutrophication of waterways…”

If plants could be bred that used phosphorus more effectively, this dependency on fertilizer could be reduced. So Hayes and colleagues examined internal P-use efficiency (PUE) by comparing three high-PUE and two low-PUE rice genotypes grown with varying phosphorus supplies.

The team found that low investment in lipid-P was strongly associated with increased photosynthetic PUE, achieved by reducing total leaf phosphorus concentration while maintaining rapid photosynthetic rates. This presents a novel pathway for increasing PUE by targeting varieties with reduced lipid-P investment. Cross-breeding the low lipid-P genes into popular varieties of rice will benefit rice production in low-P soils and in areas where fertilizer use is limited, improving global food security by reducing phosphorus fertilizer demands and food production costs.

READ THE ARTICLE

Hayes, P.E., Adem, G.D., Pariasca-Tanaka, J. and Wissuwa, M. (2022) “Leaf phosphorus fractionation in rice to understand internal phosphorus-use efficiency,” Annals of Botany, https://doi.org/10.1093/aob/mcab138