Influence of N nutrients on GS activity and putative ammonium transporter1;2 (SaAMT1;2) expression in sandal plants (Santalum album L.)

Abstract

Ammonium acts as better N source for sandal growth. The ammonium assimilation and transport is mediated by the up-regulation of putative leaf and root SaAMT1;2 in Santalum album. Nitrogen compounds play a major role in the concentration of macromolecules and expression of putative ammonium transporter1;2 (SaAMT1;2) in Santalum album (S. album) hydroponic cultures. Specific activity of glutamine synthetase (GS) and putative SaAMT1;2 expression levels were determined on the 7th, 14th and 21st day in S. album grown in nitrogen-free Hoagland’s solution supplemented with different concentrations (0-10 mM) of ammonium nitrate (NH4NO3), ammonium sulphate [NH4(SO4)2] and potassium nitrate (KNO3). Highest glutamine synthetase (GS) specific activity was observed in 0.5 mM KNO3 on the 14th day and chlorophyll content in 0.5 mM NH4NO3 on the 7th and 21st day. Highest quantity of total sugar and soluble sugar was detected in 0.5 mM NH4NO3 on the 14th day. The putative leaf and root SaAMT1;2 expression levels were positively correlated to GS specific activity, however, NH4(SO4)2 did not appreciably influence the GS specific activity and putative SaAMT1;2 expressions during the initial days. The relative expression of putative SaAMT1;2 followed an identical pattern in the NH4NO3/NH4(SO4)2 treated plants on the 7th and 21st day. The biochemical and molecular parameters indicated improved NH3 assimilation in hydroponic S. album cultures supplemented with different N compounds; however, it is time and concentration dependent.