Correlations between root phosphorus acquisition and foliar phosphorus allocation reveal how grazing promotes plant phosphorus utilization

Plant Physiol Biochem. 2024 Mar:208:108467. doi: 10.1016/j.plaphy.2024.108467. Epub 2024 Feb 23.

Abstract

Overgrazing and phosphorus (P) deficiency are two major factors limiting the sustainable development of grassland ecosystems. Exploring plant P utilization and acquisition strategies under grazing can provide a solid basis for determining a reasonable grazing intensity. Both foliar P allocation and root P acquisition are crucial mechanisms for plants to adapt to environmental P availability; however, their changing characteristics and correlation under grazing remain unknown. Here, we investigated foliar P fractions, root P-acquisition traits and gene expression, as well as rhizosphere and bulk soil properties of two dominant plant species, Leymus chinensis (a rhizomatous grass) and Stipa grandis (a bunchgrass), in a field grazing intensity gradient site in Inner Mongolia. Grazing induced different degrees of compensatory growth in the two dominant plant species, increased rhizosphere P availability, and alleviated plant P limitation. Under grazing, the foliar metabolite P of L. chinensis increased, whereas the nucleic acid P of S. grandis increased. Increased P fractions in L. chinensis were positively correlated with increased root exudates and rapid inorganic P absorption. For S. grandis, increased foliar P fractions were positively correlated with more fine roots, more root exudates, and up-regulated expression of genes involved in defense and P metabolism. Overall, efficient root P mobilization and uptake traits, as well as increases in leaf metabolic activity-related P fractions, supported plant compensatory growth under grazing, a process that differed between tiller types. The highest plant productivity and leaf metabolic activity-related P concentrations under medium grazing intensity clarify the underlying basis for sustainable livestock production.

Keywords: Foliar phosphorus fractions; Phosphorus-acquisition strategies; Root-leaf correlations; Soil phosphorus mobilization; Sustainable grazing management; Transcriptome.

MeSH terms

  • Ecosystem*
  • Nitrogen / analysis
  • Phosphorus*
  • Plants
  • Poaceae
  • Rhizosphere
  • Soil

Substances

  • Phosphorus
  • Soil
  • Nitrogen