The mobilization of protein reserves in the germinating seed requires the action of a number of proteases at appropriate times during growth of the embryo. Four such proteases have been identified in the mung bean (Vigna radiata): proteinase F, vicilin peptidohydrolase, and carboxypeptidase I and II. The levels of these proteins in mung bean cotyledons will be quantified at different stages of seed development and germination using specific antibodies. cDNA clones in lambda-gt11 for each of the proteases will be isolated and used as specific probes to characterize and quantitate protease mRNA levels. These results will be combined with those for the in vitro translatability of protease gene transcripts, and the direct determination of protease activities. These studies will pinpoint the level of control of synthesis to transcription, mRNA processing, translation, post-translational processing, or a combination thereof. The levels of proteases and their mRNAs in cotyledons detached from the embryonic axis shortly after germination will also be examined. Detachment of the cotyledons disrupts the normal pattern of changes in the proteases, and may offer insight into the role of phytohormones in the regulation of these enzymes. An important part of seed germination and seed viability is the mobilization of stored food reserves such as carbohydrate, protein and lipids. Little is known about the mobilization of protein reserves in the seeds of higher plants. It is not known why different protein-degrading enzymes appear in different amounts at different times during germination or how this process is controlled. The work described in this proposal will develop the molecular tools to study the regulation of the synthesis of four different enzymes involved in protein degradation in mung bean seeds. The development of these tools will offer in the future the potential for controlling the process of protein degradation which would impact agriculture, particularly the malting and brewing industries.//
