Effect of in planta phosphorus on aluminum-induced inhibition of root elongation in wheat
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Both aluminum (Al) toxicity and phosphorus (P) deficiency are limiting factors of crop production on acid soils. Although Al-P interaction has been extensively studied, the results are controversial. The aim of this study is to investigate the effect of in planta P on Al-induced inhibition of root elongation in wheat (Triticum aestivum L.).
Roots of wheat (cv. Atlas 66) with different internal P concentrations were prepared by two methods; split-root and re-rooting in a hydroponic solution using three different P levels (0, 25 and 250 μM) to avoid direct precipitation of Al-P in the solution. Al toxicity was evaluated by root elongation inhibition and callose induction. The Al and P concentrations in the root tips were also compared among different treatments.
Both split-root and re-rooting methods generated roots with different P concentrations in the tips when exposed to different P levels. Lower P in the root tips resulted in less Al-induced inhibition of the root elongation, less callose content and less Al accumulation, while higher root P caused a higher Al-induced inhibition of the root elongation, increased callose content and Al accumulation in the root tips. Furthermore, Al in the root cell sap was not altered by different P concentrations, but Al in the root cell wall was increased with increasing in planta P concentrations.
Al toxicity in wheat is associated with P in the root cell wall; lower root P enhanced Al tolerance, while higher root P aggravated Al toxicity in wheat.
KeywordsIn planta Phosphorus Aluminum Wheat root Cell wall Split-root Re-rooting
This investigation was financially supported by the Nation Key Basic Research Program of China (No.2014CB441000) and the Natural Science Foundation of China (No.41025005). This research was also supported in part by Joint Research Program implemented at the Institute of Plant Science and Resources, Okayama University.
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