Phosphate or nitrate imbalance induces stronger molecular responses than combined nutrient deprivation in roots and leaves of chickpea plants.

The negative effects of phosphate (Pi) and/or nitrate (NO3 - ) fertilizers on the environment have raised an urgent need to develop crop varieties with higher Pi and/or nitrogen use efficiencies for cultivation in low-fertility soils. Achieving this goal depends upon research that focuses on the identification of genes involved in plant responses to Pi and/or NO3 - starvation. Although plant responses to individual deficiency in either Pi (-Pi/+NO3 - ) or NO3 - (+Pi/-NO3 - ) have been separately studied, our understanding of plant responses to combined Pi and NO3 - deficiency (-Pi/-NO3 - ) is still very limited. Using RNA-sequencing approach, transcriptome changes in the roots and leaves of chickpea cultivated under -Pi/+NO3 - , +Pi/-NO3 - or -Pi/-NO3 - conditions were investigated in a comparative manner. -Pi/-NO3 - treatment displayed lesser effect on expression changes of genes related to Pi or NO3 - transport, signalling networks, lipid remodelling, nitrogen and Pi scavenging/remobilization/recycling, carbon metabolism and hormone metabolism than -Pi/+NO3 - or +Pi/-NO3 - treatments. Therefore, the plant response to -Pi/-NO3 - is not simply an additive result of plant responses to -Pi/+NO3 - and +Pi/-NO3 - treatments. Our results indicate that nutrient imbalance is a stronger stimulus for molecular reprogramming than an overall deficiency.