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  • Author or Editor: J. Derek Bewley x
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Abstract

An ovule passes through various contiguous phases during its development into a seed (Fig. 1). The first phase, histodifferentiation (or initial morphogenesis) (27), begins with fertilization and rapid cell division, leading to formation of the embryonic axis and of tissues that eventually accumulate reserve materials (3). Following this is the maturation or seed expansion phase, during which there is a marked increase in seed mass; cell expansion occurs as reserve deposition takes place. The 3rd and final phase, maturation drying (or desiccation), is characterized by a general reduction in metabolism as water is lost from the seed, which then passes into a quiescent, and sometimes dormant, state. This last phase is characteristic of temperate zone crops, but does not necessarily occur in tropical plants.

Open Access

High amounts of endo-β-mannanase (EC 3.2.1.78) activity were extracted from tomato (Lycopersicon esculentum Mill.) fruits when a high-salt-containing buffer was used. Two pI forms of the fruit enzyme were identified, one being much more basic than the many seed isoforms. The number of isoforms increased if a protease inhibitor was not used during extraction. The enzyme was found in the ripe fruits of many other species, and was particularly active in those of muskmelon (Cucumis melo L. Cantalupensis Group) and watermelon [Citrullus lanatus (Thunb.) Matsum. and Nak.]. In most fruits, enzyme activity was localized in the skin and the epidermal and subepidermal regions. The enzyme in several fruits had a molecular weight of ≈40,000 and reacted immunologically with the tomato seed endo-β-mannanase antibody.

Free access