Protein to cut waste

Published in the journal Plant Physiology, the findings provide a deeper understanding of the mechanisms whereby plants sense how much and when to take in the essential nutrient, phosphorus, for optimal growth.

Lead author Ricarda Jost, from the Department of Plant, Animal and Soil Sciences at La Trobe University said the environmental and economic benefits to farmers could be significant.

‘‘In countries like Australia, where soils are phosphorus poor, farmers are using large amounts of expensive, non-renewable phosphorus fertiliser, such as superphosphate or diammonium phosphate (DAP), much of which is not being taken up effectively by crops at the right time for growth,’’ Dr Jost said.

‘‘Our findings have shown that a protein called SPX4 senses the nutrient status — the ‘amount of fuel in the tank’ of a crop — and alters gene regulation to either switch off or turn on phosphorus acquisition, and to alter growth and flowering time.

‘‘The protein senses when the plant has taken in enough phosphorus and tells the roots to stop taking it up.

‘‘If the fuel pump is turned off too early, this can limit plant growth.’’

La Trobe agronomist James Hunt said the research findings were good news as Australian farmers continued to need to be as efficient as possible with costly fertiliser inputs.

‘‘In our no-till cropping systems, phosphorous gets stratified in the top layers of soil,’’ Dr Hunt said.

‘‘When this layer gets dry, crops cannot access these reserves and enter what we a call a phosphorus drought.

‘‘The phosphorous is there, but crops can’t access it in the dry soil.

‘‘If we could manipulate crop species to take up more phosphorous when the top soil is wet, we’d be putting more fuel in the tank for later crop growth when the top soil dries out.’’

The research team will now be investigating in more detail how SPX4 interacts with gene regulators around plant development and controlling flowering time.