ISOLATION AND IMMUNOAFFINITY PURIFICATION OF BIOLOGICALLY-ACTIVE PLANT NATRIURETIC PEPTIDE

It has recently been demonstrated that antibodies against atrial natri uretic peptides (ANP) recognise analogues in plants and that rat ANP b inds specifically to isolated plant membranes and promotes stomatal gu ard cell opening in a concentration dependent manner. Here we report t he isolation and immunoaffinity purification of plant natriuretic pept ide (PNP) from ivy (Hedera helix) with rabbit anti-alpha-ANP (1-28) (h uman, canine) antiserum. We also demonstrate that immunoaffinity purif ied plant peptide induces stomatal opening in a concentration dependen t manner. This is therefore the first report of an active indigenous p eptide hormone in plants. We propose that PNPs are part of a signallin g system that has evolved early in evolution and is involved ill the r egulation of ion transport and transpiration in plants. (C) 1997 Acade mic Press.