Abstract:
An increasing body of evidence suggests that in plants, as in vertebrates, biologically active natriuretic peptide (NP) hormones play an important role in the regulation of the osmotic and ionic balance. The evidence includes isolation and immunoaffinity purification of biologically active natriuretic peptide analogues (irPNP) from ivy that promoted stomatal opening and specifically, rapidly and transiently increased cGMP levels in root conductive tissue. In this study we demonstrate that I125 -rat atrial natriuretic peptide (rANP) binds to plasma membranes from leaf and stem tissue of Tradescantia multiflora and importantly, both unlabelled rANP and irPNP can competitively displace that binding. In addition, tissue section autoradiography reveals specific in situ binding of I125 -rANP to leaf and stem tissue. The findings are consistent with the presence of a biologically active NP system in plants and suggest that NPs signal through a dedicated receptor system.
Abbreviations:
ANP: atrial natriuretic peptide IB: incubation buffer irPNP: biologically active plant natriuretic peptide analogues NP: natriuretic peptide rANP: rat ANP
Key words:
Natriuretic peptides - autoradiography - homeostasis -
Tradescantia multiflora.
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C. A. Gehring
Deakin University School of Biological and Chemical Sciences
Geelong
Victoria 3217
Australia
Section Editor: T. Nagata
Email: cage@deakin.edu.au