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Ca 2+ effects on ethylene, carbon dioxide and 1‐aminocyclopropane‐1‐carboxylic acid synthase activity
Author(s) -
Burns Jacqueline K.,
Evensen Kathleen B.
Publication year - 1986
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.1399-3054.1986.tb05588.x
Subject(s) - ethylene , climacteric , lycopersicon , chemistry , ripening , incubation , carbon dioxide , 1 aminocyclopropane 1 carboxylic acid , horticulture , nuclear chemistry , botany , biochemistry , food science , organic chemistry , biology , catalysis , genetics , menopause
The response of pericarp disks from ripening tomato ( Lycopersicon esculentum Mill. cv. Traveler‘76) to CaCl 2 , additions was studied to determine the effect of Ca 2+ on ethylene and CO 2 production. Application of 5 m M CaCl 2 resulted in a 2, 20, 33, 39, and 50% increase in ethylene production in disks obtained from preclimacteric minimum, climacteric rise, climacteric peak, one, and two days postclimacteric fruit, respectively. CaCl 2 concentrations of 10 and 50 m M gave no additional stimulation of ethylene production; CO 2 production at 5 m M CaCl 2 was not different from controls, but is increased at 10 and 50m M CaCl 2 . CaCl 2 also increased ethylene production in disks treated with 1‐aminocyclopropane‐1‐carboxylic acid (ACC) or aminoethoxy‐vinylglycine. Chloride salts of K + , Na + , Mg 2+ , Sr 2+ and La 3+ did not stimulate ethylene production. SrCl 2 stimulated ethylene production to a lesser degree than CaCl 2 . Disks from potato ( Solanum tuberosum L. cv. Katahdin) tubers produced greater quantities of ethylene and ACC when 5 m M CaCl 2 was included in the incubation medium (K. B. Evensen, 1983. Physiol. Plant. 60:125–128). Ca 2+ ‐treated disks had more than three times as much ACC synthase activity as control disks after 18 to 24 h incubation, when ethylene and ACC were maximal. The apparent K m for S‐adenosylmethionine was 13 μ M at 29°C, pH 8.0 in extracts from both Ca 2+ ‐treated and control disks. Inclusion of 1 to 50 m M CaCl 2 in the assay medium did not significantly affect enzyme activity. ACC synthase extracted from control and Ca 2+ ‐treated disks had a pH optimum of 8.5 and an apparent molecular weight of 72 kdalton, estimated by gel filtration. It is likely that the presence of Ca 2+ in the buffer allows greater synthesis of ACC synthase as part of the wound‐healing response in potato, while in tomato the predominant effect is on membrane stabilization.