Metabolic alterations provide insights into Stylosanthes roots responding to phosphorus deficiency

Abstract Background Low phosphorus (P) availability is a major constraint on the growth of plants, especially in acid soils. Stylosanthes (stylo) is a pioneer tropical legume with several adaptive strategies to cope with P deficiency, but its metabolic reprogramming during P limitation remain poorly understood. Results To shed light on the acclimation of stylo roots to low P stress, morphophysiological and metabolic response were investigated in this study. After 15 days of low P treatment, shoot dry weight and total P concentration were markedly hampered, whereas root growth, root APase activity, root antioxidant activity were markedly enhanced. Corresponding investigation of metabolic profiling showed that a total of 256 metabolites with differential accumulation in response to P deficiency were identified in stylo roots, mainly including sugars, organic acids, amino acids, nucleotides, phenylpropanoids and their derivatives. P deficiency leads to significant reduction in the levels of phosphorylated sugars and nucleotides, indicates that the known strategies of P scavenging from P-containing metabolites are observed. The metabolisms of organic acids and amino acids were also remodeled by P limitation, which suggests that P-deficient stylo roots redistribute their carbohydrates in responding P deprivation, by releasing organic acids into the rhizosphere to mobilize phosphate from P complexes and employing amino acids as alternative carbon resource for energy metabolism. In phenylpropanoid metabolism pathway, the increased accumulation flavonoids, as well as up-regulated expression of involved genes SgF3H, SgF3’H, SgFLS, might contribute to enhance the antioxidant activity of stylo roots, especially kaempferol, quercetin, dihydromyricetin. The enhanced accumulation isoflavonoids with differential expression of related genes (SgHID and SgUGT) supported the opinion of isoflavonoids secreted to function with rhizosphere microbes in responding to P deficiency condition, especially daidzein and rotenone. Conclusions This study provides valuable insights generated from stylo roots into the various adaptation responses to Pi-starvation, identified candidate genes and metabolites will make some contributions to detect potential target region for future developing Pi-efficiency breeding research.