A non-ACC pathway for ethylene biosynthesis in Botrytis cinerea
Altaf Qadir, Errol W. Hewett, Peter G. Long and David R. Dilley
Postharvest Biology and Technology, Volume 62, Issue 3, December 2011, Pages 314-318
2011
บทคัดย่อ
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 ∝-keto-methylthiobutyric acid (KMBA) was added to a defined (modified Pratts) medium. Although 1-aminocyclopropane-1-carboxylic acid (ACC) did not stimulate ethylene production, ∝-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 (Co2+) was inhibitory, but after a 4-d lag period ethylene production from B. cinerea cultures containing methionine and Co2+ reached the same level as those without Co2+. [U 14C] methionine was converted to 14C-ethylene with high efficiency indicating that it is a direct precursor, while [2,314C]-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.