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First published online November 24, 2004; 10.1104/pp.104.045765 Plant Physiology 136:4184-4197 (2004) © 2004 American Society of Plant Biologists Effect of the Colorless non-ripening Mutation on Cell Wall Biochemistry and Gene Expression during Tomato Fruit Development and Ripening1,[w]Warwick HRI, Wellesbourne, Warwick CV35 9EF, United Kingdom (E.M.E., K.M., L.H., J.A., G.B.S.); Plant Research International, 6700 AA Wageningen, The Netherlands (A.B.); Unilever Research and Development, Colworth, Sharnbrook, Bedford MK44 1LQ, United Kingdom (J.D.S.); and Division of Nutritional Biochemistry, University of Nottingham, Loughborough, Leics LE12 5RD, United Kingdom (G.A.T.)
The Colorless non-ripening (Cnr) mutation in tomato (Solanum lycopersicum) results in mature fruits with colorless pericarp tissue showing an excessive loss of cell adhesion (A.J. Thompson, M. Tor, C.S. Barry, J. Vrebalov, C. Orfila, M.C. Jarvis, J.J. Giovannoni, D. Grierson, G.B. Seymour [1999] Plant Physiol 120: 383390). This pleiotropic mutation is an important tool for investigating the biochemical and molecular basis of cell separation during ripening. This study reports on the changes in enzyme activity associated with cell wall disassembly in Cnr and the effect of the mutation on the program of ripening-related gene expression. Real-time PCR and biochemical analysis demonstrated that the expression and activity of a range of cell wall-degrading enzymes was altered in Cnr during both development and ripening. These enzymes included polygalacturonase, pectinesterase (PE), galactanase, and xyloglucan endotransglycosylase. In the case of PE, the protein product of the ripening-related isoform PE2 was not detected in the mutant. In contrast with wild type, Cnr fruits were rich in basic chitinase and peroxidase activity. A microarray and differential screen were used to profile the pattern of gene expression in wild-type and Cnr fruits. They revealed a picture of the gene expression in the mutant that was largely consistent with the real-time PCR and biochemical experiments. Additionally, these experiments demonstrated that the Cnr mutation had a profound effect on many aspects of ripening-related gene expression. This included a severe reduction in the expression of ripening-related genes in mature fruits and indications of premature expression of some of these genes in immature fruits. The program of gene expression in Cnr resembles to some degree that found in dehiscence or abscission zones. We speculate that there is a link between events controlling cell separation in tomato, a fleshy fruit, and those involved in the formation of dehiscence zones in dry fruits.
1 This work was supported by funding from Unilever Research UK. G.B.S. and K.M. were funded by the Biotechnology and Biological Sciences Research Council, UK. E.M.E. was funded on a Unilever postgraduate fellowship to G.B.S. [w] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.045765. * Corresponding author; e-mail graham.seymour{at}warwick.ac.uk; fax 44(0)2476574500. Received May 5, 2004; returned for revision October 4, 2004; accepted October 12, 2004. This article has been cited by other articles:
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