Effects of calmodulin antagonists on auxin-stimulated proton extrusion in Avena sativa coleoptile segments |
| |
Authors: | Francisco Gonzá lez-Daró s,Joaquin Carrasco-Luna,Angeles Calatayud,Julio Salguero,Secundino del,Valle-Tascó n |
| |
Affiliation: | Univ. de València, Dept de Biologia Vegetal, c/Dr. Moliner 50, E-46100 Burjassot, València, Spain. |
| |
Abstract: | 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 Ca2+-CaM system on auxin-dependent medium acidification. |
| |
Keywords: | Abraded coleoptiles amino acid release auxin Avena sativa calcium calmidazolium calmodulin compound 48/80 medium acidification medium buffer capacity oat trifluoperazine W-5 W-7 |
|
|