© 1988 Heron Publishing—Victoria, Canada
Protein synthesis in slash pine callus cultures exposed to water stress
J. V. Valluri (1), W. J. Treat (2), R. J. Newton (1), B. G. Cobb (3) and E. J. Soltes (1)
1. Department of Forest Science, Texas Agricultural Experiment Station, Texas A&M University System, College Station, TX 77840,
USA / 2. Department of Agricultural Engineering, Texas Agricultural Experiment Station, Texas A&M University System, College Station,
TX 77840, USA / 3. Department of Horticultural Sciences, Texas Agricultural Experiment Station, Texas A&M University System, College Station,
TX 77840, USA / Received October 7, 1987
Summary
Effects of water stress on protein synthesis were investigated in heterotrophic callus cultures derived from slash pine (Pinus elliottii Engelm.) cotyledon explants. Cultures were transferred to medium containing 0–15% mannitol to provide water potentials between
–0.4 and –2.5 MPa. Beginning between 0 and 22 h after transfer to the new medium, cultures were incubated for 2 h with 35S-methionine. Both the uptake of label and the incorporation of label into protein decreased with decreasing medium water
potential. Incorporation, however, was reduced to a greater extent than uptake suggesting that the reduced incorporation was
at least partly the result of reduced protein synthesis. Separation of labeled proteins by one-dimensional SDS-polyacrylamide
gel electrophoresis and visualization by fluorography revealed the induction of two new protein bands after incubation at
–1.8 MPa for 24 h. Induction of new proteins was not observed at other water potentials or after shorter incubation times.
Protein bands from cultures incubated at –1.8 MPa for 24 h and then transferred for 24 h to mannitol-free medium (–0.4 MPa)
were comparable to those from control cultures maintained on mannitol-free medium throughout.
