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Calcium regulation of exogenous and endogenous 1‐aminocylopropane‐1‐carboxylic acid bioconversion to ethylene
Author(s) -
Cheverry J. L.,
Pouliquen J.,
Guyader H.,
Marcellin P.
Publication year - 1988
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.1399-3054.1988.tb04940.x
Subject(s) - ethylene , chemistry , endogeny , calcium , 1 aminocyclopropane 1 carboxylic acid , incubation , biochemistry , cytosol , enzyme , biophysics , biology , catalysis , organic chemistry
Ethylene production and overall levels of free and conjugated 1‐aminocyclopropane‐1‐carboxylic acid (ACC) were studied in parenchymatous tissues, excised from clmacteric apples ( Malus domestica Borkh. cv. Granny Smith) and infiltrated with an incubation medium containing 0, 1, 10 or 100 m M Ca 2+ , with or without exogenous ACC (2 m M ). Irrespective of whether exogenous ACC was applied or not, ethylene production was inhibited to the same extent (40%) by an apoplastic effect of 100 m M Ca 2+ . In the absence of external ACC, the inhibition was associated with an increase in total endogenous ACC and may be related to a reduction in the rate of the last step of ethylene pathway. This suggests that the ethylene‐forming enzyme (EFE) is localized in the plasma membrane. Low Ca 2+ concentrations (1 m M ) enhanced basal ethylene synthesis due to influx of Ca 2+ into the cytosol, while overall concentrations of ACC in the tissue decreased. However, 1 m M Ca 2+ did not stimulate ACC‐dependent ethylene formation. Thus, Ca 2+ influx may stimulate the translocation of endogenous ACC from synthesis or storage compartment (s) to reactive site(s) of the plasma membrane. The concentration of 10 m M Ca 2+ had no effect on basal ethylene production and appears to represent a balance point between the stimulating and inhibiting effects of 1 and 100 m M Ca 2+ , respectively, Furthermore, the charge‐times of exogenous ACC observed with 0, 1 and 10 m M Ca 2+ suggest that EFE is located on the inner side of the plasma membrane.