MOLECULAR STUDIES ON OSMOPRIMED SEEDS OF CAULIFLOWER - A PARTIAL AMINO-ACID-SEQUENCE OF A VIGOR-RELATED PROTEIN AND OSMOPRIMING-ENHANCED EXPRESSION OF PUTATIVE ASPARTIC PROTEASE

A partial amino acid sequence of a vigour-related protein, V-1, from cauliflower (Brassica oleracea L.) seeds was obtained, after isolation by two-dimensional gel electrophoresis and gas-phase microsequencing. The sequence was found to have high homology to soybean seed maturation proteins. However, the position of the sequence in the V-1 polypeptide suggests that the V-1 and soybean proteins have different polypeptide structures. An osmoprimed seeds cDNA library was constructed and has been screened by a cDNA probe derived from the V-1 sequence. Two cDNA clones with high homology to aspartic protease (EC 3.4.23) from barley grain were isolated. The expression of putative aspartic protease mRNA was found to be enhanced by osmopriming, however the clones were found to have no significant sequence homology to the V-1.