Endo‐β‐mannanase is present in an inactive form in ripening tomato fruits of the cultivar Walter

• Published in: Journal of experimental botany Vol. 52; no. 354; pp. 105 - 111
• Main Authors: Banik, Mitali, Bourgault, Richard, Bewley, J. Derek
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.01.2001; OXFORD UNIVERSITY PRESS
• Subjects: Agronomy. Soil science and plant productions; Antibodies; Biological and medical sciences; Blotting, Southern; Blotting, Western; Cell walls; DNA; Economic plant physiology; Endo‐β‐mannanase; Enzymes; fruit; Fruit - enzymology; Fruit - ultrastructure; Fruits; Fundamental and applied biological sciences. Psychology; Gels; Hemic system; inactive enzyme; Lycopersicon esculentum; Lycopersicon esculentum - classification; Lycopersicon esculentum - enzymology; Lycopersicon esculentum - genetics; Mannosidases - metabolism; Messenger RNA; Microscopy, Confocal; Nutrition. Photosynthesis. Respiration. Metabolism; Pericarp; Regulation of Growth, Development and Whole Organism Physiology; Ripening; RNA; Seeds; Seeds - physiology; tomato; Fruit; Enzyme; Inactivation; Tomato; Mannan endo-1,4-β-mannosidase; Regulation(control); Vegetable crop; Enzymatic activity; Dicotyledones; Glycosidases; Angiospermae; Lycopersicon esculentum; Hydrolases; Spermatophyta; Solanaceae; Intraspecific comparison; O-Glycosidases; Cultivar
• DOI: 10.1093/jexbot/52.354.105
• ISSN: 0022-0957

Fruits of the tomato cultivar Walter undergo normal development to the red‐ripe stage but, unlike those of the cultivar Trust, they do not produce any active endo‐β‐mannanase. Reasons for this failure to produce the enzyme were sought. The cv. Walter contains genes for endo‐β‐mannanase, as shown by Southern blot analysis, and transcripts for the enzyme are present in ripening fruits, as revealed using Northern hybridization. Moreover, the enzyme protein is detectable by Western blots using an endo‐β‐mannanase‐specific antibody from tomato. In addition, the inactive enzyme is localized appropriately in the wall regions of the outer layers of the fruit (skin and outer pericarp). Mixing inactive fruit extracts of cv. Walter, in excess, with extracts from cv. Trust fruits, which contain active enzyme, leads to an increase rather than a reduction in enzyme activity, showing that there are no inhibitors of endo‐β‐mannanase in cv. Walter fruits. Similar results were obtained with fruits of the tomato cv. Heinz 1439. In contrast to the situation in fruits, the seeds of both cvs Walter and Heinz 1439 produce active enzyme, especially following germination.