Identification Of Phosphorus Accumulators And Relevant Mechanism Of Phosphorus Uptake

1.Movement of soluble phosphates (Pi) from phosphorus-impacted soils poses tremendous threats to the degradation of the aquatic and other eco-systems and triggers serious environmental consequences. Plant-assisted clean-up strategies have demonstrated great advantages over conventional methods in redundant phosphorus removal from soils. Phosphorus accumulation potentials were investigated for 12 dominant plant species growing in a phosphorus mining area in Shifang, as well as their corresponding non-mining ecotypes growing in Ya'an, China. High phosphorus concentrations were observed in the seedling and flowering stages of two species, Pilea sinofasciata and Polygonum hydropiper, up to 16.23 and 8.59 g kg^-1 respectively, which were 3.4 and 7 times higher than in the non-mining ecotypes. Available phosphorus levels in the respective rhizosphere soils of these plants were 112.84 and 121.78 mg kg^-1, 12 and 4 times higher than in the non-rhizosphere soil. Phosphorus concentrations in shoots of the mining ecotypes of all 12 species were significantly negatively correlated with available phosphorus in the rhizosphere soils (p＜0.05), whereas a positively correlation was observed in the non-mining ecotypes. The results suggested that Pilea sinofasciata and Polygonum hydropiper were efficient candidates among the tested species for phosphorus accumulation in shoots, and that further studies should be conducted to investigate their potential to be adopted as phosphorus accumulators.2.In this study, phosphorus concentration, physiological and biochemical characteristics of Polygonum hydropiper leaves in the phosphorus mining ecotype (ME) and the non-mining ecotype (NME) were investigated under different soil phosphorus status. The results showed that significant increase (p＜0.05) in biomass was observed in ME with ascending soil phosphorus, while reverse tendency was observed in NME. The phosphorus concentration in Polygonum hydropiper leaves was higher than in the shoot and root. The phosphorus accumulation of Polygonum hydropiper was 3-5 times higher than in NME. Significant increase in available phosphorus concentration in rhizosphere was observed in both ecotypes after planting, the increase in ME was 1.05-63.02 times higher than in NME. Chlorophyll a and chlorophyll b of leaves in ME increased proportionally with the ascending soil phosphorus. The plants of ME growing under higher phosphorus concentration presented higher bio-activities of CAT, SOD and POD than under low phosphorus conditions. Significant increase (p＜0.05) in activity of SOD was observed in ME with ascending soil phosphorus, nearly 634% higher than the control at 200 mg P kg^-1, while reverse tendency was observed in NME. Significant increase (p<0.05) in concentration of malondialdehyde (MDA) was observed in the NME, while reverse tendency was manifested in plants from the ME.3. In this study, Phosphorus concentration, physiological and biochemical characteristics of Pilea sinofasciata leaves in the phosphorus mining ecotype (ME) and the non-mining ecotype (NME) were investigated under different soil P status. Significant increase (p＜0.05) in biomass was observed in ME with ascending soil phosphorus, while reverse tendency was observed in NME. The biomass of the mining ecotype was nearly 246% higher than in the non-mining ecotype at 200 mg P kg^-1. Significant increase (p<0.05) in phosphorus concentration of shoot was observed in ME with ascending soil phosphorus, while reverse tendency was observed in NME. The phosphorus accumulation of shoot in ME was nearly 10-276% higher than in NME. The results showed that chlorophyll a and of leaves in ME increased proportionally with the ascending soil P. No significant variation was observed both in ME and NME. The plants of ME growing under high P concentration presented higher bio-activities of CAT, SOD and POD than under low P conditions. Significant increase (p＜0.05) in concentration of malondialdehyde (MDA) and free proline was observed in the NME, while reverse tendency was manifested in plants from the ME.