Ethylene and carbon dioxide production by developing strawberries show a correlative pattern that is indicative of ripening climacteric fruit

Abstract

Laser photoacoustic spectroscopy continuously quantified the ethylene (C 2 H 4 ) produced by strawberry flowers and fruits developing in planta. C 2 H 4 was first detected as flower buds opened and exhibited diurnal oscillations (to approximately 200 pl flower −1 h −1 ) before petal abscission. Exogenous application of silver thiosulphate (STS) to detached flowers inhibited petal abscission and flower senescence. In fruit, C 2 H 4 production was maintained at a ‘low level’ (10–60 pl fruit −1 h −1 ) until fruit expanded when levels increased in a diurnal pattern (to 200 pl fruit −1 h −1 ). After expansion, C 2 H 4 production declined to a low level until fruit attained the red‐ripe stage for at least 24 h. After this time, C 2 H 4 levels increased linearly (no diurnal fluctuation) to approximately 1 nL fruit −1 h −1 . Twenty‐four hours after the re‐initiation of C 2 H 4 production by red fruit, CO 2 levels increased approximately three‐fold, indicative of a respiratory climacteric. STS applied to fruits developing in planta and dissected fruit parts ex situ established that C 2 H 4 production is regulated by negative feedback until fruits had expanded. The C 2 H 4 produced by red‐ripe fruit was regulated by positive feedback. Anti‐1‐amino‐cyclopropane‐1‐carboxylic acid oxidase IgG localization identified immunoreactive antigens of 40 and 30 kDa (M r ) within the fruit achenes of expanding and red‐ripe fruit. Analysis of dissected fruit showed that seed C 2 H 4 accounts for 50% the C 2 H 4 that is detectable from ripe fruit.