TaPHL7 Transcription Factor Regulates Utilisation of Nitrogen and Phosphorus in Wheat.

Macronutrients nitrogen and phosphorus are essential for plant growth and development, thus being crucial for the productivity of crops. However, the molecular mechanism regulating the utilisation of nitrogen and phosphorus remains elusive. Here, we show that the wheat (Triticum aestivum L.) transcription factor PHOSPHATE STARVATION RESPONSE-LIKE7 (TaPHL7) regulates nitrogen and phosphorus utilisation. TaPHL7 binds to the promoter of TaGS1;3, encoding a key enzyme of nitrogen assimilation, to repress its expression. Nitrate relieves the transcriptional repression on a subset of nitrogen utilisation genes imposed by TaPHL7. Conversely, TaPHL7 activates the expression of a subset of Pi transporter genes, thus promoting both nitrogen utilisation and Pi acquisition. In developing seeds, TaPHL7 expression is progressively attenuated, leading to the increased expression of TaGS1;3, thus enhancing nitrogen reassimilation. Notably, mutations in TaPHL7 cause increased nitrogen remobilisation efficiency, early maturation and accelerated grain filling, eventually boosting grain yield. Moreover, TaPHL7-1A has been subjected to artificial selection during wheat breeding. We propose that TaPHL7 regulates the utilisation of nitrogen and phosphorus, thus representing a promising target for genetic improvement of wheat.