Auxin-induced changes in the patterns of protein synthesis in soybean hypocotyl.

The patterns of protein synthesis in elongating and mature (basal) sections of soybean hypocotyl were examined after incubation in a medium containing auxin (auxin-treated) or a medium lacking auxin (untreated). The hypocotyl sections (1.2 cm) were labeled with [(35)S]methionine, and polypeptide patterns were analyzed by one- and two-dimensional polyacrylamide gel electrophoresis. Auxin treatment altered the pattern of protein synthesis in both elongating and basal soybean hypocotyl sections. Excision of terminal segments from incubated sections was required to clearly observe auxin-induced changes in the synthesis of polypeptides. Polypeptides synthesized in terminal segments, possibly in response to wounding, can mask subtle changes in the spectrum of polypeptides synthesized in response to auxin. Cytokinin treatment caused a decrease in [(35)S]methionine incorporation into polypeptides and altered the pattern of protein synthesis in untreated and auxin-treated elongating hypocotyl sections.