Protein Synthesis as a Requirement for Wound Xylem Differentiation

Abstract

AbstractAn increasing rate of protein synthesis was observed during the first 2 days after the isolation of 2 mm thick internodal stem slices of Coleus on a sucrose‐agar medium. This rise in the rate of protein synthesis preceeded the first visible signs of wound‐vessel member differentiation in the cultured stem slices. Irradiation of tissue slices with 4000 R of x‐rays at isolation reduced the numbers of wound‐vessel members differentiated after 7 days in culture by 51 per cent, and this level of x‐irradiation was observed to inhibit protein synthesis by the cultured stem slices. Treatment of the tissue slices with exogenous auxin (0.05 mg/1) after irradiation did not alter the degree of inhibition of xylem differentiation. Actinomycin D inhibited wound‐vessel member differentiation, but it had no effect on the endogenous growth of the cultured stem slices. Similarly, auxin at 0.05 mg/1 was without effect on the endogenous growth rate of the stem slices. Actinomycin D treatment was highly effective in inhibiting xylem differentiation if it was supplied to the tissues within the first 48 hours after isolation; actinomycin D treatment had no significant effect on xylem differentiation when it was given after the first 2 days of culture. Chloramphenicol (10−3M) inhibited both xylem differentiation and the endogenous growth of the cultured stem slices.