Characterization of an axis-specific protein from mungbean expressed late during seed maturation

A low molecular weight (LMW) protein found in abundance in the dry axis of mungbean Vigna radiata L. Wilczek was purified to homogeneity. Its pi was f ound to be. 7.9. Antibody raised against the protein was used to screen a c DNA library made from maturing mungbean embryo (18-19 d after flowering) in an expression vector system, lambda-gt11. A full-length cDNA clone (VRLEA1 2.1) encoding the polypeptide was isolated by innmunoscreening. The cDNA se quence showed a single major open reading frame for a highly hydrophilic, 1 12 amino acid polypeptide of relative molecular mass 14 192 Da. Messenger R NA and protein accumulate specifically in the embryonic axis and not in any other part of the plant under normal conditions. The protein is synthesize d starting 9 d after flowering and accumulates until seed desiccation with the greatest amount found in the dry seed; northern analysis also confirmed this. Sequence homology and differential expression reveals that this is a n abscisic acid-responsive protein encoded by a multigene family. (C) Elsev ier, Paris.