Auxin-Induced Specific Changes in the Pattern of Protein Synthesis in Soybean Hypocotyl Sections

Abstract

It is generally agreed that continued protein synthesis is required for the expression of auxin-induced cell elongation, but controversy has existed over whether this response involves the synthesis of any specific “growth-limiting” proteins. To help resolve this controversy, we have employed the high-resolution two-dimensional gel electrophoresis system described by O’Farrell (1) to examine the spectrum of polypeptides synthesized in elongating soybean hypocotyl sections which were incubated in a medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) (auxin-treated) or lacking 2,4-D (untreated). We have also utilized this technique to analyze the polypeptides synthesized in untreated and auxin-treated sections of mature (basal) soybean hypocotyls where auxin enhances the level of RNA and protein synthesis relative to that observed in untreated sections (2). Our results indicate that auxin treatment alters the pattern of protein synthesis and/or causes a charge modification of proteins in both elongating and basal sections of soybean hypocotyl.