Find in Library

Phosphorus (P) is a major limiting factor for legume and symbiotic nitrogen fixation (SNF). Although overall adaptations of legumes to P supplementation have been extensively studied in connection with inorganic P, little information is currently available regarding nodulation or SNF responses to organic P (Po) in hydroponics. We investigated the mineral and carbon metabolism of Po-induced nodules of two contrasting faba bean varieties grown hydroponically under inorganic P (Pi), viz., in P-deficient (2 µM KH₂PO_4, −Pi), sufficient-P (200 µM KH₂PO₄, +Pi), and phytic acid (200 µM, Po) conditions, and were inoculated with <i>Rhizobium leguminosarum</i> bv. <i>viciae</i> 3841 and grown for 30 days. The results consistently reveal similar growth and biomass partitioning patterns between +Pi and Po, with both varying substantially from −Pi. In comparison, +Pi and Po observed equivalent accumulations of overall elemental P concentrations, with both increasing by 114 and 119%, respectively, relative to −Pi. A principal component analysis on metabolites showed a clear separation of the −Pi treatment from the others, with +Pi and Po correlating closely together, highlighting the nonsignificant differences between them. Additionally, the δ¹⁵N abundance of shoots, roots, and nodules was not significantly different between treatments and varieties and exhibited negative δ¹⁵N signatures for all tissues. Our study provides a novel perspective on mineral and carbon metabolism and their regulation of the growth, functioning, and reprogramming of nodules upon phytate supply.