Large variation of maize lines in acclimation to low phosphate availability and the synergistic coupling to nitrogen

Abstract

Phosphorus (P) is an essential plant nutrient with low bioavailability in soils, and its uptake and that of nitrogen (N) are crucial for optimal growth. Here, diverse maize genotypes with distinct breeding histories, including doubled haploids from landraces, were grown under two P levels. The genotypes showed substantial variation in internal P concentrations and in performance under low P. Several lines maintained adequate N regardless of P supply; however, two lines from the heterotic dent pool performed poorly under low P and exhibited N deficiency. Only these lines lacked a robust transcriptional phosphate starvation response (PSR) in roots. Although N-related gene expression varied among lines, it did not explain differences in N acquisition. Inositol pyrophosphates (PP-InsPs), potential key regulators of P status signalling, were similarly diminished in contrasting lines under P deficiency, suggesting that they may be required, but not sufficient for PSR responses in roots. Overall, the results reveal large genotypic variation in low-P responses, line-specific N–P interactions at the post-transcriptional level and a critical role of shoot-root communication, which are discussed in the context of differential responses to P availability.