Ethylene modulates wheat response to phosphate deficiency.

Ethylene involves in the response to P deficiency in some model plants, but its relevance to wheat remains limited. Following our recent study demonstrating the role of differentially expressed genes (DEGs) encoding ethylene response factors (ERFs) in response to P starvation in wheat, this study aims to investigate the remodelling of ethylene pathway and the physiological roles of ethylene in wheat under P deficiency using transcriptome analysis and the addition of exogenous ethylene analogue ethephon or ethylene inhibitors. ERFs with at least a two-fold change upon P deficiency were biasedly enriched on chromosome 4 B. A group of genes encoding ACC synthase and ACC oxidase were upregulated under P starvation, indicating an increase in ACC and ethylene content, which was verified by biochemical measurements and gas chromatography-mass spectrometry analysis. Under P deficiency, both root and shoot biomass decreased with the application of exogenous ethephon or ethylene inhibitors, while root fork numbers and root surface area decreased upon ethephon treatment. The phosphate (Pi) concentrations in roots and old leaves increased with ethephon treatment, and it's redistribution in roots and younger leaves was altered under Pi starvation. Our findings could serve as a guideline for breeding germplasm with high Pi efficiency.