Physiological And Molecular Mechanism Of The High Phosphorous Utility Efficiency In Thellungiella Salsuginea

A comprehensive knowledge of the mechanisms regulating phosphate use efficiency (PUE) is required to reduce excessive input of phosphate (P) fertilizers while maintaining acceptable crop yields under limited phosphate supply. Studying plant species which are naturally adapted to low phosphate conditions could facilitate the identification of novel regulatory genes conferring better PUE. Here we show that Thellungiella salsuginea, a halophytic relative of Arabidopsis thaliana grows better than Arabidopsis under either sufficient(1.5 mM phosphate) or limited(P free) phosphate conditions,which imply a higher utilizing capability. Thellungiella could absorb higher amounts of phosphate under P-limitation compared to Arabidopsis,which indicates a higher incorporating power.To get a further knowledge of the mechanism of this high efficiency, we measure a range of morphology and physiology indexes of both the two species under different nutrition treatments.In accordance with our prediction,the roots of Ts can secret more protons and phophatases which enhance phosphate uptaken from the environment.By contrast,we haven't seen the roots of Ts proliferate,particularly its lateral roots are inhibited while P is omitted.The results also prove that Thellungiella could generate more chlorophylls,phosphoric carbohydrates and starch which determines that the photosythesis is less affected,and the production forms of photosythesis can release more free phosphate for the metabolism and recycling.In Thellungiella,anthocyanin as a mark of stress accumulated less under P-limitation.On molecular level,we searched and cloned some ESTs of Thellungiella .Northern blotting shows that LPS genes in Thellungiella,phosphate tranporter genes,acid phosphatase genes express also upgrade but less obviously .Above all,our work suggest that Thellungiella is tolerant to P-limited conditions and could act as a model system to unravel the mechanisms for low phosphate tolerance.