cellulase and 1-methylcyclopropene

Anxi persimmon is a popular fruit because of its appealing flavor and rich nutrients such as polysaccharides. However, the harvested persimmon fruit softens and deteriorates quickly. This study explored the influences of the treatment of papers containing 1-methylcyclopropene (1-MCP) on the contents of cell wall polysaccharides and activities of cell wall-degrading enzymes in harvested Anxi persimmons, as well as its effect on fruit softening. The results demonstrated that, in comparison to the control Anxi persimmons, the Anxi persimmons treated with 1.35 μL/L 1-MCP manifested higher fruit firmness, higher contents of protopectin, cellulose, and hemicellulose, but a lower level of water-soluble pectin, lower activities of pectin methylesterase, polygalacturonase, cellulase, and β-galactosidase in Anxi persimmons during postharvest storage. These findings suggested that the treatment of papers containing 1.35 μL/L 1-MCP could retard softening of harvested Anxi persimmon fruit via inhibiting the degradation of cell wall polysaccharides.

Topics: Cell Wall; Cellulase; Cyclopropanes; Diospyros; Food Storage; Fruit; Paper; Polygalacturonase; Polysaccharides

Ethylene induced cotton (Gossypium hirsutum var RST-39) leaf abscission has been characterized by measuring the activities of ACC synthase (ACS, E.C. 4.4.1.14), ACC oxidase (ACO, E.C. 1.14.17.4) and cellulase (E.C. 3.2.1.4). In addition, a leaf abscission specific cDNA (GhCel1) has been cloned from cotton, which belongs to the alpha(2) subgroup of cellulases that possess a C-terminus carbohydrate-binding domain. Measurement of enzyme activity in the abscission zones of cotton leaf explants exposed to ethylene for 48h compared to non-treated controls indicated a more than 5-fold increase in the activity of ACS, 1.2-fold increase in the activity of ACO and about 2.7-fold increase in the activity of cellulase in the ethylene treated explants. This increase was accompanied by a substantial decrease in the force required to separate the petiole from the stem (break strength) and an increased accumulation of cellulase transcript in the abscission zone. Treatment of explants with 1-Methylcyclopropene (1-MCP) prior to ethylene resulted in significant inhibition of enzyme activities and transcript accumulation. It is concluded that ethylene response of cotton leaf abscission leads to higher cellulase expression and increased activities of ethylene biosynthesis enzymes in the abscission zone.

Topics: Abscisic Acid; Amino Acid Oxidoreductases; Cellulase; Cloning, Molecular; Cyclopropanes; Ethylenes; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Gossypium; Lyases; Plant Growth Regulators; Plant Leaves; Plant Proteins; Protein Structure, Tertiary; Time Factors

In order to investigate the physiological role of ethylene in the initiation and subsequent progression of softening, pear fruit were treated with propylene, an analogue of ethylene or 1-methylcyclopropene (1-MCP), a gaseous inhibitor of ethylene action at the preclimacteric or ripening stages. The propylene treatment at the pre-ripe stage stimulated ethylene production and flesh softening while the 1-MCP treatment at the same stage markedly retarded the initiation of the ripening-related events. Moreover, 1-MCP treatment after the initiation of ripening markedly suppressed the subsequent flesh softening and ethylene production. These results clearly indicate that ethylene is not merely a by-product, but plays a crucial role in both the initiation and maintenance of regulating the softening process during ripening. The observations also suggest that ethylene in ripening is regulated entirely in an autocatalytic manner. The mRNA accumulation of pear polygalacturonases (PG) genes, PC-PG1 and PC-PG2, was in parallel with the pattern of fruit softening in both propylene and 1-MCP treatments. However, the expression pattern of pear endo-1,4-beta-D-glucanases (EGase) genes, PC-EG1 and PC-EG2, was not affected in both treatments. The results suggest that ethylene is required for PGs expression even in the late ripening stage, but not for EGases.

Topics: Alkenes; Cellulase; Cloning, Molecular; Cyclopropanes; Ethylenes; Fruit; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Isoenzymes; Molecular Sequence Data; Phylogeny; Plant Proteins; Polygalacturonase; Pyrus; RNA, Messenger