Some Aspects of Protein Metabolism in Tamarix tetragyna Roots Grown in a Saline Substrate

Abstract

Various aspects of protein metabolism were studied in T. tetragyna roots grown at various levels of salinity. Salinity in the growth medium as well as salinity present in the reaction mixture interfered with uptake and incorporation of L-[14C]leucine into a fraction insoluble in trichloroacetic acid. Uptake did not appear to limit incorporation, although both processes were affected by salinity. Growing the roots in – 3 atm NaCl increased their ability for uptake and incorporation of the externally supplied amino acid. Salinity during growth resulted in both quantitative and qualitative changes in the natural amino acid composition of the fraction insoluble in trichloroacetic acid. The amount of proline and hydroxyproline increased considerably, while valine and methionine decreased. Methionine sulphoxide and another unidentified substance were found only in the proteins of roots grown in the presence of high levels of salinity. Salinity also induced an increase in the hydroxyproline content of the cell wall fraction and modified the metabolism of exogenously supplied labelled proline. The results are compared with the effects of salinity on protein metabolism of pea roots, and the differences noted.