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A non-ACC pathway for ethylene biosynthesis in Botrytis cinerea
- Qadir, Altaf, Hewett, Errol W., Long, Peter G., Dilley, David R.
- Postharvest biology and technology 2011 v.62 no.3 pp. 314-318
- ethylene, 1-aminocyclopropane-1-carboxylic acid, cobalt, fruits, pyridoxal phosphate, aminocyclopropanecarboxylate oxidase, Botrytis cinerea, acids, chlorides, ethylene production, biochemical pathways, enzymatic reactions, methionine, kiwifruit
- Premature softening and tissue senescence occur in kiwifruit infected with Botrytis cinerea. While ethylene production is enhanced in infected fruit and B. cinerea produces ethylene on defined media in vitro the source of ethylene in this pathosystem is unclear. Ethylene production by B. cinerea was enhanced when methionine or â-keto-methylthiobutyric acid (KMBA) was added to a defined (modified Pratts) medium. Although 1-aminocyclopropane-1-carboxylic acid (ACC) did not stimulate ethylene production, â-aminooxyacetic acid (AOA) was inhibitory suggesting a role for a pyridoxal phosphate mediated enzyme reaction down stream from the methionine/KMBA stimulated ethylene biosynthetic pathway. Cobalt chloride (CoÂ²âº) was inhibitory, but after a 4-d lag period ethylene production from B. cinerea cultures containing methionine and CoÂ²âº reached the same level as those without CoÂ²âº. [U Â¹â´C] methionine was converted to Â¹â´C-ethylene with high efficiency indicating that it is a direct precursor, while [2,3 Â¹â´C]-ACC did not yield radioactively labelled ethylene. These results suggest that the ethylene biosynthetic pathway in B. cinerea does not involve ACC as a precursor and that the enzyme responsible for synthesising ethylene is similar to, but different from, ACC oxidase from higher plants. The ethylene biosynthetic pathway in B. cinerea is yet to be determined.