Abstract: Phosphorus is one of the most important mineral elements for plant growth and development, and different nitrogen forms can regulate phosphorus uptake. As is well-known that plant plasma membrane (PM) H⁺-ATPase plays an important role in nutrition uptake, it may also relate to the different nitrogen-modulated phosphorus uptake. In our study, PM H⁺-ATPase in tea roots were isolated by two-phase partitioning in aqueous dextranT-500 and polyethylene glycol, and the effect of different nitrogen forms on phosphorus uptake and the characteristic parameters of PM H⁺-ATPase in tea roots were examined by using non-invasive micro-test technique and Western-blot. It was found that ammonium significantly improved the phosphorus accumulation in tea plants as compared with nitrate nutrition. In addition, less depolarized PM potentials, higher net H⁺ flux, PM H⁺-ATPase activities and protein levels were found under ammonium treatment than those under nitrate nutrition treatment. Furthermore, vanadate (the PM H⁺-ATPase inhibitor) significantly decreased phosphorus accumulation in tea plants under ammonium and nitrate nutrition treatments, which further suggests that PM H⁺-ATPase may be involved in phosphorus accumulation in tea plants regulated by different nitrogen forms.

Key words: ammoniacal nitrogen, nitrate nitrogen, phosphorus absorption, PM H⁺-ATPase, tea plants