Endo‐β‐mannanase activity increases in the skin and outer pericarp of tomato fruits during ripening

• Published in: Journal of experimental botany 2000-03, Vol.51 (344), p.529-538
• Main Authors: Bewley, J. Derek, Banik, Mitali, Bourgault, Richard, Feurtado, J. Allan, Toorop, Peter, Hilhorst, Henk W.M.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Antibodies; beta-Mannosidase; Biological and medical sciences; Blotting, Northern; Blotting, Western; Cell and Molecular Biology, Biochemistry and Molecular Physiology; Cell walls; Economic plant physiology; endo‐β‐mannanase; Enzyme activity; Enzymes; Fructification and ripening; Fructification, ripening. Postharvest physiology; Fruit - enzymology; Fruit - physiology; Fruits; Fundamental and applied biological sciences. Psychology; Gels; Growth and development; Lycopersicon esculentum; Lycopersicon esculentum - enzymology; Lycopersicon esculentum - physiology; Mannosidases - biosynthesis; Mannosidases - metabolism; Microscopy, Confocal; Pericarp; Plant physiology and development; Plant Proteins - analysis; Ripening; RNA; RNA, Messenger - analysis; Seeds; softening; Tomato; Vegetative and sexual reproduction, floral biology, fructification
• ISSN: 0022-0957; 1460-2431; 1460-2431
• DOI: 10.1093/jexbot/51.344.529

Activity of endo‐β‐mannanase increases during ripening of tomato (Lycopersicon esculentum Mill.) fruit of the cultivar Trust. β‐Mannoside mannohydrolase is also present during ripening, but its pattern of activity is different from that of endo‐β‐mannanase. The increase in endo‐β‐mannanase activity is greatest in the skin, and less in the outer and inner pericarp regions. This enzyme is probably bound to the walls of the outermost cell layers of the fruit during ripening, and it requires a high‐salt buffer for effective extraction. The enzyme protein, as detected immunologically on Western blots, is present during the early stages of ripening, before any enzyme activity is detectable. The mRNA for the enzyme is also present at these stages; endo‐β‐mannanase may be produced and sequestered in a mature‐sized inactive form during early ripening. Most non‐ripening mutants of tomato exhibit reduced softening and lower endo‐β‐mannanase activity, but a cause‐and‐effect relationship between the enzyme and ripening is unlikely because some cultivars which ripen normally do not exhibit any endo‐β‐mannanase activity in the fruit.