UoH Study Reveals How Tomato Plants Reuse Phosphate
UoH researchers identified a molecular mechanism that helps tomato plants remobilise stored phosphate, potentially improving fertiliser-use efficiency.
Researchers at the University of Hyderabad (UoH) have identified a molecular mechanism that helps tomato plants move stored phosphate from older leaves to younger, growing tissues, potentially offering a way to improve crops’ ability to use fertiliser more efficiently.
Manipulating this mechanism could eventually help develop high-yielding and resilient crop varieties that make better use of their internal nutrient reserves, the researchers found. Such crops could reduce farmers’ fertiliser input costs and potentially limit soil degradation associated with excessive fertiliser use, they said.
The study, published in the ‘Journal of Experimental Botany’, identified the tomato PAP26b gene as a key driver of phosphate remobilisation in seedlings. The research was carried out by Abhishek Roychowdhury and team under the guidance of Prof. Rahul Kumar at The Tomato Lab, Department of Plant Sciences, School of Life Sciences, UoH, according to a statement.
Phosphate is essential for plant growth, but agriculture relies heavily on chemical phosphate fertilisers, which are expensive and made from non-renewable resources, Improving a plant’s ability to reuse phosphate already stored in its tissues could therefore reduce its dependence on external fertiliser, UoH explained in a statement.
The researchers found that when PAP26b was silenced, older leaves lost their ability to effectively transfer stored phosphate. This triggered a systemic phosphate-starvation response in younger leaves and roots even when the plant was growing under normal nutrient conditions.
The response involved ‘SlPHL1’, called the master regulator of phosphate signalling, and miR399, a microRNA involved in regulating the plant’s phosphate balance. The researchers also found that the response was tissue-specific. While young leaves and roots responded as though they were phosphate deficient, older leaves on the same plant remained unaffected.
The findings indicated that different leaf positions within a single plant could maintain distinct phosphate-signalling and nutrient-balance mechanisms. The study identifies the ‘SlSPX2–SlPHL1 regulatory module’, which is modulated by the PAP26b gene, as a potential genetic target for improving internal phosphate use efficiency (PUE).
The researchers’ findings add to efforts to improve nutrient-use efficiency by understanding not just how plants absorb nutrients from soil, but how they redistribute and reuse nutrients already available within the plant.