EFFECTS OF 2,4-D REMOVAL ON THE SYNTHESIS OF SPECIFIC PROTEINS BY CATHARANTHUS-ROSEUS CELL-CULTURES

Total and neosynthesized proteins of periwinkle cell suspensions (Cath aranthus roseus) were first investigated in cells grown in a 2,4-D-con taining medium. Analysis of total (silver-stained) proteins by two-dim ensional gel electrophoresis revealed that the levels of seventeen pol ypeptides were altered during the growth cycle of the cells. Analysis of in vivo [S-35]-methionine labeled polypeptides revealed differences in the synthesis of at least 35 polypeptides. Three polypeptides with molecular masses of 30, 35 and 39 kDa appeared to be specific markers of the early stationary phase. In a second sequence of experiments, c ells were grown in a 2,4-D-free medium. Alterations in protein synthes is were observed: several polypeptides were expressed earlier in the 2 ,4-D-starved cells than in control cells; the synthesis of at least tw o specific polypeptides was increased in cells grown in 2,4-D-free med ium, whereas the synthesis of three other polypeptides (molecular mass es 33, 34 and 52.5 kDa) was switched on in these cells. As previous st udies showed that 2,4-D depletion increased the alkaloid production in C. roseus cells, the present results may suggest that these polypepti des are implicated in the regulation of the alkaloid pathway.