Anatomy of ethylene-induced floral-organ abscission in Chamelaucium uncinatum (Myrtaceae)

Macnish, Andrew J., Irving, Donald E., Joyce, Daryl C., Vithanage, Vasanthe and Wearing, Alan H. (2005) Anatomy of ethylene-induced floral-organ abscission in Chamelaucium uncinatum (Myrtaceae). Australian Journal of Botany, 53 2: 119-131.

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Author Macnish, Andrew J.
Irving, Donald E.
Joyce, Daryl C.
Vithanage, Vasanthe
Wearing, Alan H.
Title Anatomy of ethylene-induced floral-organ abscission in Chamelaucium uncinatum (Myrtaceae)
Journal name Australian Journal of Botany   Check publisher's open access policy
ISSN 0067-1924
Publication date 2005
Sub-type Article (original research)
DOI 10.1071/BT04075
Volume 53
Issue 2
Start page 119
End page 131
Total pages 13
Editor S. Farrer
Place of publication Melbourne, Australia
Publisher CSIRO Publishing
Collection year 2005
Language eng
Subject C1
300304 Post Harvest Technologies
620209 Ornamentals, Australian natives and nursery plants
070605 Post Harvest Horticultural Technologies (incl. Transportation and Storage)
Abstract Postharvest abscission of Geraldton waxflower (Chamelaucium uncinatum Schauer) flower buds and flowers is ethylene-mediated. Exposure of floral organs to exogenous ethylene (1 mu L L-1) for 6 h at 20 degrees C induced separation at a morphologically and anatomically distinct abscission zone between the pedicel and. oral tube. Flower buds with opening petals and flowers with a nectiferous hypanthium were generally more responsive to exogenous ethylene than were flower buds enclosed in shiny bracteoles and aged (senescing) flowers. The anatomy of abscission-zone cells did not change at sequential stages of floral development from immature buds to aged flowers. The zone comprised a layer of small, laterally elongated-to-rounded, closely packed and highly protoplasmic parenchyma cells. Abscission occurred at a two- to four-cell-wide separation layer within the abscission zone. The process involved degradation of the middle lamella between separation layer cells. Following abscission, cells on both the proximal and distal faces of the separation layer became spherical, loosely packed and contained degenerating protoplasm. Central vascular tissues within the surrounding band of separation layer cells became torn and fractured. For flower buds, bracteoles that enclose the immature floral tube also separated at an abscission zone. However, this secondary abscission zone appeared less sensitive to ethylene than the primary ( central). oral-tube abscission zone as bracteoles generally only completely abscised when exposed to 10 mu L L-1 ethylene for the longer period of 24 h at 20 degrees C. The smooth surfaces of abscised separation-layer cells suggest that hydrolase enzymes degrade the middle lamella between adjacent cell walls.
Keyword Plant Sciences
Harvested Geraldton Waxflower
Electron Microscopy
Pedicel Abscission
Flower Abscission
Ultrastructure
Fruit
Grevillea
Nectaries
Meristem
Sultani
Q-Index Code C1
Additional Notes Submitted: 28 May 2004 Accepted: 1 November 2004 Published: 31 March 2005

 
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