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Effects of calmodulin antagonists on auxin‐stimulated proton extrusion in Avena sativa coleoptile segments
Author(s) -
GonzálezDarós Francisco,
CarrascoLuna Joaquin,
Calatayud Angeles,
Salguero Julio,
ValleTascón Secundino
Publication year - 1993
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1993.tb08792.x
Subject(s) - coleoptile , avena , auxin , calmodulin , trifluoperazine , chemistry , apoplast , biophysics , biochemistry , botany , biology , enzyme , cell wall , gene
The effect of the 5 calmodulin (CaM) antagonists trifluoperazine (TFP). compound 48/80, N‐(6‐aminohexyl)‐naphthalenesulfonamtde (W‐5), N‐(6‐aminohexyl)‐5‐chloro‐1‐naphthalenesulfonamide (W‐7), and calmidazolium on auxin‐dependent medium acidification was investigated in abraded segments of Avena sativa L. cv. Victory I. Buffering capacity, Asn content, and changes in pH of bathing solutions were measured in the presence of these inhibitors. When coleoptiles were treated with TFP or compound 48/80, the Asn content and the buffering capacity increased, thus suggesting that plasma membrane permeability was modified. On the contrary. the effect of calmidazolium, W‐5. and W‐7 on Asn release and buffering capacity was rather low; only small effects being observable at the highest concentration employed. Calmidazolium and W‐7 strongly inhibited auxin‐dependent medium acidification. W‐5 did not affect medium acidification. The specificity of these CaM antagonists and their effects on medium acidification are discussed. The data adduced is consistent with the working hypothesis which postulates an essential role for the Ca 2+ ‐CaM system on auxin‐dependent medium acidification.