Maize (Zea mays L.) coleoptile segments loaded with 45Ca released about 50% of the ion after 1 h when treated with indoleacetic acid (IAA). In contrast, fusicoccin (FC) had no effect. The same relation was found when ATP-dependent Ca2+ transport, measured as 45Ca uptake, was determined in a plasmalemma-rich membrane vesicle fraction isolated from coleoptiles treated or untreated for 1 h with IAA or FC. In fact, IAA-treated membranes showed an increase in ATP-dependent 45Ca uptake by more than 30% with respect to the control and the FC treatment. Ca2+ uptake in IAA-treated membranes was only slightly affected (+27%) by supplying calmodulin (Cam) exogenously. However, Ca2+ uptake in membranes from the control and FC-treated coleoptiles were stimulated (+80%) by exogenous Cam. Calmidazolium, a Cam antagonist, inhibited Ca2+ uptake in the IAA treatment (-48%) to a greater extent with respect to the control and FC treatment (-33 and -29%, respectively). A possible relationship between the effect of IAA on the ATP-dependent Ca2+ transport activity, the involvement of Cam, and their effect on growth are discussed.
Calcium transport in membrane vesicles isolated from maize coleoptiles : effect of indoleacetic acid and fusicoccin / G. Zocchi, G. Rabotti. - In: PLANT PHYSIOLOGY. - ISSN 0032-0889. - 101:1(1993 Jan), pp. 135-139. [10.1104/pp.101.1.135]
Calcium transport in membrane vesicles isolated from maize coleoptiles : effect of indoleacetic acid and fusicoccin
G. Zocchi;G. Rabotti
1993
Abstract
Maize (Zea mays L.) coleoptile segments loaded with 45Ca released about 50% of the ion after 1 h when treated with indoleacetic acid (IAA). In contrast, fusicoccin (FC) had no effect. The same relation was found when ATP-dependent Ca2+ transport, measured as 45Ca uptake, was determined in a plasmalemma-rich membrane vesicle fraction isolated from coleoptiles treated or untreated for 1 h with IAA or FC. In fact, IAA-treated membranes showed an increase in ATP-dependent 45Ca uptake by more than 30% with respect to the control and the FC treatment. Ca2+ uptake in IAA-treated membranes was only slightly affected (+27%) by supplying calmodulin (Cam) exogenously. However, Ca2+ uptake in membranes from the control and FC-treated coleoptiles were stimulated (+80%) by exogenous Cam. Calmidazolium, a Cam antagonist, inhibited Ca2+ uptake in the IAA treatment (-48%) to a greater extent with respect to the control and FC treatment (-33 and -29%, respectively). A possible relationship between the effect of IAA on the ATP-dependent Ca2+ transport activity, the involvement of Cam, and their effect on growth are discussed.Pubblicazioni consigliate
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