ISHS Acta Horticulturae 398: Postharvest Physiology of Fruits
CALCIUM TRANSPORT AND ATPASE ACTIVITY IN MICROSOMAL VESICLE FRACTION FROM 'MONTMORENCY' SOUR CHERRY FRUIT |
| Authors: | J.L. Anderson, W.F. Campbell |
| Keywords: | Calcium, Fruit firmness, Sour cherry, Prunus cerasus, Plasma membrane |
| Abstract:
Calcium maintains plasma membrane integrity, osmoregulation and extends the post-harvest firmness of 'Montmorency' sour cherry, Prunus cerasus L. Experiments were conducted on plasma membrane vesicles from pre-and post-harvest Ca-treated sour cherry fruit to ascertain calcium transport and K+-stimulated ATPase activity. Cherry trees were sprayed with a solution of Calcium Metalosate® [an amino acid calcium chelate (AACa), Albion Laboratories, Inc., Clearfield, UT] and cherry clusters were dipped in AACa or calcium chloride (CaCl2). Samples from mechanically harvested trees and hand-harvested fruit from dip treatments were processed for membrane-enriched vesicle fractions. Membrane protein content was about 4-fold greater in Ca-treated fruit than in controls. In the absence of adenosine triphosphate (ATP), approximately 1 nmol of Ca2+ mg protein-1 was associated with the membrane vesicles after 15 min and remained constant. Upon the addition of ATP and Mg2+, active Ca2+ uptake into the plasma membrane vesicles was observed. Addition of the Ca2+ ionophore A23187 caused an immediate release of accumulated free Ca2+. ATP-dependent Ca2+ was not inhibited by 10 μM oligomycin. ATPase activity and H+-pumping were both completely inhibited by orthovanadate, suggesting that the fractions were free from nonplasma membrane ATPases. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
