Expression of vegetative storage protein (VSP-β) in soybean raceme tissues8

Abortion of flowers and pods (>25%) appears to be part of the normal developmental sequence in Glycine max [L.] Merr. Slow growth rates of seeds and pods, and development of an abscission zone in raceme tissues subtending flowers destined to abort contribute to this loss, but the processes leading to these events have not been elucidated. Rescue of soybean flowers destined to abort was accomplished by removal of proximal flowers and/or application of 1 mM benzyladenine (BA) before anthesis. Raceme tissues (axes and pedicels, including the abscission zone) subtending setting and aborting flowers were examined for differential protein expression to identify gene products that were directly associated with the induction of flower set. Induction to set was associated with increased protein concentrations. Transcription and translation of a soybean vegetative storage protein (VSP-β) in the subtending raceme tissues was directly linked to flower set. Cytokinin application increased growth of raceme tissues independent of fruit set. A model system for future studies of regulation of soybean flower set and abortion is presented.