Coordinate expression of ribosomal protein mRNAs following auxin treatment of soybean hypocotyls.

Nine recombinant plasmids containing soybean (Glycine max. var. Wayne) ribosomal protein mRNA sequences were identified by hybrid selection-translation followed by gel electrophoresis. Individual plasmids were used to determine the amount of ribosomal protein mRNA in soybean hypocotyls at various times after application of the synthetic auxin (2,4-dichlorophenoxy)acetic acid. Results from these experiments indicate that the relative abundance of ribosomal protein mRNAs increases 3-8-fold within 24 hr of (2,4-dichlorophenoxy)acetic acid application. Earlier in vitro translation data (Gantt, J. S., and Key, J. L. (1983) Biochemistry 22, 4131-4139) also indicated that the ribosomal protein message levels increase following treatment with auxin. However, the two methods of quantifying mRNA lead to significantly different values for the amount of induction for three ribosomal protein mRNAs. The cause of these differences is not known. An increase in the level of the ribosomal protein mRNAs can be detected 1 h after treatment with (2,4-dichlorophenoxy)acetic acid. The similar kinetics of induction of these messages suggests that their levels are coordinately regulated.