UNUSUAL SEQUENCES OF GROUP-3 LEA MESSENGER-RNA INDUCIBLE BY MATURATION OR DRYING IN SOYBEAN SEEDS

Two cDNA clones, pGmPM8 and pGmPM10, which correspond to two mRNA spec ies in mature or dry soybean seeds, were characterized. The deduced pr oteins, based on DNA sequence analysis, have a molecular mass of 49 an d 51 kDa for pGmPM8 and pGmPM10, respectively. These two cDNA clones s hare a high homology with an amino acid identity of about 90% between the two deduced proteins. Both proteins appear to be extremely hydroph ilic except at their N-termini that contain a 29 amino acid hydrophobi c region at the N-terminus and the sizes of proteins decrease after co -incubating with ER membranes. These two proteins contain more than 30 similar, contiguous repeats of Il amino acids, which is characteristi c of group 3 LEA proteins. The mRNAs corresponding to pGmPM8 and pGmPM 10 were expressed at high levels in dried or mature soybean seeds, but not in fresh immature seeds. The RNAs were also present in abscisic a cid (ABA) treated leaves or cultured cells, and in tissues subjected t o water stress or low temperatures.