ZmPHR1 contributes to drought resistance by modulating phosphate homeostasis in maize

Abstract

SummaryAs an essential macronutrient, phosphorus (P) is often a limiting nutrient because of its low availability and mobility in soils. Drought is a major environmental stress that reduces crop yield. How plants balance and combine P‐starvation responses (PSRs) and drought resistance is unclear. In this study, we identified the transcription factor ZmPHR1 as a major regulator of PSRs that modulates phosphate (Pi) signaling and homeostasis. We found that maize zmphr1 mutants had reduced P concentration and were sensitive to Pi starvation, whereas ZmPHR1‐OE lines displayed elevated Pi concentration and yields. In addition, 57% of PSR genes and nearly 70% of ZmPHR1‐regulated PSR genes in leaves were transcriptionally responsive to drought. Under moderate and early drought conditions, the Pi concentration of maize decreased, and PSR genes were up‐regulated before drought‐responsive genes. The ZmPHR1‐OE lines exhibited drought‐resistant phenotypes and reduced stomatal apertures, whereas the opposite was true of the zmphr1 mutants. ZmPT7‐OE lines and zmspx3 mutants, which had elevated Pi concentration, also exhibited drought resistance, but zmpt7 mutants were sensitive to drought. Our results suggest that ZmPHR1 plays a central role in integrating Pi and drought signals and that Pi homeostasis improves the ability of maize to combat drought.