Effect of phosphorus deficiency on phytase activity of faba bean ([i]Vicia faba[/i])-rhizobia symbiosis

Legume-rhizobia symbiosis provides the necessary nitrogen for plant growth and contributes to the improvement of soil nitrogen balance. However, this symbiosis is limited by many environmental constraints such as phosphorus (P) deficiency. Indeed, this major element is massively under insoluble forms in soil since it is strongly associated with aluminum, iron and calcium. Besides, the effect of P deficiency on phosphatases activities, particularly phytases has been widely studied in some N2-fixing legumes. The current study develops the impact of P deficiency on phytase activity in eight faba bean (Vicia faba)-rhizobia symbiosis. The experiment was carried out in a greenhouse on four faba bean varieties (Aguadulce, Alfia, Luz de Otono and Reina Mora) inoculated with two local rhizobia isolated from farmers ‘fields in Al Haouz region. The P deficiency was applied by adding low KH2PO4 concentration (25μmol plant-1 week-1) to nutrient solution while the control received 125μmol plant-1 week-1. The plants were harvested at flowering stage and their growth evaluated. P content as well as phytase activities were assessed in nodules. The results showed a significant impact of phosphorus deficiency on plant growth and nodules P content for all the studied combinations. Besides, phytase activities were highly stimulated in nodules under P deficiency. A further analysis of a phytase gene transcription in nodules was performed using RTPCR method showed its localization in the nodule corte