AOBPreview originally published online on October 24, 2002
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Annals of Botany 90: 765-773, 2002
© 2002 Annals of Botany Company
Structural Basis of the Rind Disorder Oleocellosis in Washington Navel Orange (Citrus sinensis L. Osbeck)
1 Department of Horticulture, Viticulture and Oenology, Waite Campus, The University of Adelaide, Glen Osmond, South Australia 5064, Australia
* For correspondence. Fax +61 8 8303 7116, e-mail margaret.sedgley{at}adelaideedu.au
Received: 1 July 2002; Returned for revision: 7 August 2002; Accepted: 18 September 2002 Published electronically: 24 October 2002
Oleocellosis, a physiological rind disorder of citrus fruit, is an unattractive surface blemish caused by phytotoxic effects of released rind oils. The development of oleocellosis in Washington navel orange (Citrus sinensis L. Osbeck) was examined by following a time sequence of surface symptoms and microscopic rind changes. The two natural causes of oleocellosis were simulated: mechanical damage to the fruit and transfer of rind oil between fruit. Mechanical fruit injury resulted in rupture of the epidermis above oil glands. Released surface oil appeared to infiltrate the rind via the ruptured epidermis resulting in rapid degeneration of cortical, but not epidermal, cell contents. Oil application to the rind surface produced a more severe blemish than did mechanical damage. The oil appeared to diffuse through the cuticle causing degeneration of the contents of all cell layers, including the epidermis. Loss of membrane integrity was detected within 30 min, followed by cell content degeneration and cell collapse. The resulting blemish, characterized by rind collapse and darkening, developed substantially within 3 d and was attributed to the cellular damage.
Key words: Oleocellosis, rind disorder, rind oil, Washington navel orange, Citrus sinensis L. Osbeck, light microscopy, electron microscopy, confocal microscopy.