Characterization of L-[5- 13C]-Proline Biosynthesis in Halophytic and Nonhalophytic Suspension Cultures by 13C NMR

Abstract

Summary L-[5- 13 C]-Proline biosynthesis by the suspension cultures of two monocotyledonous halophytes ( Distichlis spicata L. and Spartina pectinata L.) and two nonhalophytes ( Petunia hybrida Vilm. and Panicum miliaceum L.) is described. Suspension cultures were transferred to medium containing 5mM L-[5- 13 C]- glutamic acid and 0, 130 or 380 mM NaCl for 24 h. 13 C-Glutamic acid was taken up at a rate of 14 to 112μmolg -1 24h -1 . 13 C-Label in the cells was found as L-[ 13 C-5]-proline as determined by 13 C NMR. In 380 mM NaCl, D. spicata contained the most 13 C-proline (8.1% of total proline) as compared with the other species (3.1 to 4.2%). 13 C-Proline increased in Petunia transferred to higher NaCl, while S. pectinata and P. miliaceum had more 13 C-proline (5.3 and 8.6%, respectively) on 130 mM NaCl than on 380 mM NaCl (3.7% and 3.1%, respectively). The proline biosynthetic enzymes of D. spicata may be better protected against inhibition by NaCl than those of the other species.