Electron-energy-loss spectroscopic imaging of calcium and nitrogen in the cell walls of apple fruits |
| |
Authors: | I Max Huxham Michael C Jarvis Lynette Shakespeare Colin J Dover David Johnson J Paul Knox Graham B Seymour |
| |
Institution: | (1) Cell and Molecular Biology Division, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK, GB;(2) Department of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK, GB;(3) Horticulture Research International, Wellesbourne, Warwick, CV35 9EF, UK, GB;(4) Horticulture Research International, East Malling, West Malling, Kent, ME19 6BJ, UK, GB;(5) Centre for Plant Biochemistry and Biotechnology, University of Leeds, Leeds LS2 9JT, UK, GB |
| |
Abstract: | Changes in texture are an integral part of ripening in most fleshy fruits and these changes are thought to be determined,
primarily, by alterations in cell wall structure. Electron energy loss spectroscopy (EELS) imaging was used to obtain quantitative
information on the levels of calcium and nitrogen in the cell walls of apple (Malus domestica Borkh. cv. Cox's Orange Pippin) fruits. Samples of fruit cortex were prepared for EELS by high-pressure freezing and molecular
distillation drying to minimize loss and redistribution of soluble cell wall components such as calcium. The EELS imaging
successfully resolved calcium and nitrogen levels in the middle lamella and primary cell wall. When the elemental compositions
of the cell walls of Cox's apples from two sites in the UK were compared at harvest or after 6 months storage, the orchard
which always produced consistently firmer fruit had significantly lower levels of cell wall calcium and higher levels of cell
wall nitrogen. This result was unexpected since firm texture in apples and other fruits has been commonly associated with
elevated levels of fruit calcium. The nitrogen-rich material in the sections used for EELS was insoluble in acidified methanol,
indicating that it represented a high-molecular-weight component in the cell wall. Furthermore, total tissue hydroxyproline
levels were greatest in material with elevated cell wall nitrogen, suggesting enhanced levels of wall structural proteins
in the tissue. These data indicate a correlation between increased amounts of cell wall nitrogen and firm fruit texture. The
possible role of cell wall proteins in determining the textural properties of fruit tissue is discussed.
Received: 19 November 1998 / Accepted: 28 January 1999 |
| |
Keywords: | : Calcium (EELS imaging) Cell wall Fruit texture Malus (fruit cell wall) Nitrogen (EELS imaging) |
本文献已被 SpringerLink 等数据库收录! |
|