EXPRESSION PATTERNS OF GENES ENCODING SEED TRYPSIN-INHIBITORS IN PISUM-SATIVUM

In Pisum sativum (pea) seeds, trypsin inhibitor (TI) activity increase d in both axes and cotyledons during seed development. TI activities w ere appreciably higher in axes than in cotyledons and gel analyses sho wed that some TI isoforms accumulated differentially in the two organs . The maximal amounts of TI mRNA were very similar in axes and cotyled ons but, in contrast to increased TI activities, RNA amounts decreased during desiccation in both organs; however, there were differences be tween the two organs in the temporal pattern of mRNA accumulation. In situ hybridization analyses of developing axes showed the presence of TI mRNA initially in the root cap, at later Stages in parenchyma cells of the radicle and finally in the shoot apex. Immunolocalization of T I protein in developing axes showed that its spatial distribution was very similar to that of the mRNA. The organ specificity of TI gene exp ression was investigated by Northern analyses, which showed that mRNA corresponding to seed-expressed TI genes was not present in vegetative organs of the plant under normal growing conditions. TI mRNA was indu ced, however, in roots of plants that had been subjected to drought co nditions, suggesting a possible function for these proteins in dehydra ting plant tissues. (C) 1998 Elsevier Science Ireland Ltd.