RELATIONS BETWEEN DNA RNA AND PROTEIN SYNTHESIS AND CELLULAR BASIS OF GROWTH RESPONSE IN GIBBERELLIC ACID-TREATED PEA INTERNODES

A study was made of the influence of gibberellic acid (GA2) on nucleic acid, protein, and cell-wall synthesis in pea internodes in vivo.2. GA3-treated fifth internodes finally contained more than twice as much total RNA and protein as comparable untreated ones, and the contents of RNA and protein were closely related to the length of internode cortical cells.3. Cell elongation, RNA, protein, and cell-wall synthesis were stimulated 24-48 h before there was any demonstrable GA3 effect on DNA synthesis and cell division.4. Treated fifth internodes finally contained twice as many cortical cells as control internodes, a response that was matched by a proportionate increase in the amount of DNA.5. Internodes treated with actinomycin D or cycloheximide failed to elongate in response to GA3 treatment, indicating that both RNA and protein synthesis are essential for gibberellin-stimulated cell elongation to occur in this tissue.6. 5-fluorodeoxyuridine at concentrations which completely block cell division did not prevent cells from elongating in the presence of GA3.7. With the possible exception of pectic substances there was no change in the relative proportions of each of the major cell-wall constituents in treated, as compared to control internodes. © 1969 OXFORD UNIVERSITY PRESS.