Cellulase Activity during the Maturation and Ripening of Tomato Fruit

Abstract

SUMMARY An enzyme that attacks carboxymethyl cellulose may be extracted efficiently from tomato fruit by salt solutions. From a high initial value in small green fruit, activity fell gradually during fruit swelling. With incipient ripeness, the activity increased again and continued to rise to the full red condition. The green areas of “blotchy” ripened fruit showed 40% less activity than the adjacent red tissue. Fruit of tomato species in the sub‐genus Eriopersicon contained considerably more activity than examples from the sub‐genus Eulycopersicon. Firmness measurements on fruit from both sub‐genera were not significantly correlated with the cellulase activities, and from this and other evidence it is concluded that is is not a major factor controlling the softening of at fruit, at least during the ripening period.

Differential Expression of Two Endo-1,4-β-Glucanase Genes in Pericarp and Locules of Wild-Type and Mutant Tomato Fruit

“…After the BR stage, a ripening-related increase in cell-wall hydrolases has been described (Fischer and Bennett, 1991), including increases in mRNA abundance and activity of PG (Brady et al, 1982;DellaPenna et al, 1986) and EGases (Hall, 1964;Hobson, 1968;Lashbrook et al, 1994). In pericarp the mRNA abundance of both Cell and Cell increases markedly at the BR stage ( Figs.…”

“…An increase in extractable carboxymethylcellulase activity during tomato fruit ripening has been described in many studies (Hobson, 1968;Babbitt et al, 1973) and can be correlated with a decrease in the molecular size of cell-wall hemicelluloses (Huber, 1983;Tong and Gross, 1988), including xyloglucan (Sakurai and Nevins, 1993;Maclachlan and Brady, 1994). Extractable carboxymethylcellulase activity is presumably due to EGases, which in tomato are encoded by a multigene family (Brummell et al, 1994;Lashbrook et al, 1994).…”

“…One class of cell-wall hydrolases, cellulases or EGases (EC 3.2.1.4), has been specifically implicated in a number of developmental processes, including cell expansion (Hayashi and Maclachlan, 1984) and organ abscission (Sexton and Roberts, 1982), as well as ripening-associated fruit softening (Hall, 1964;Hobson, 1968;Christoffersen et al, 1984).…”

Cell Wall Metabolism in Ripening Fruit (IX. Synthesis of Pectic and Hemicellulosic Cell Wall Polymers in the Outer Pericarp of Mature Green Tomatoes (cv XMT-22)

“…This model is supported by anatomical work that demonstrated the breakdown of middle lamella polymers (Ben-Arie et al, 1979), by numerous studies characterizing the ripening-related changes in cell wall polymers (Gross and Wallner, 1979;Ahmed and * Corresponding author; e-mail jmlabavitch@ucdavis.edu; fax 1-916 -752-8502. Labavitch, 1980;Gross, 1984), and by studies that demonstrated increases in the activities of some putative cell wall polysaccharide hydrolases during ripening (Hobson, 1968;Tucker et al, 1982;Brady et al, 1983;Pressey, 1989; for review, see Fischer and Bennett, 1991). However, work involving antisense RNA (Sheehy et al, 1988) and chimeric gene expression (Giovannoni et al, 1989) has demonstrated that pectin degradation by PG is insufficient to explain ripening-related tissue softening.…”

Partial Characterization of Cx Cellulase and Cellobiase from Ripening Tomato Fruits

“…Extracts from pea epicotyls contain both C. cellulase (6,10) and cellobiase activity (5). Apparently the only suggestion of the existence of an exocellulase in higher plants was made without supporting data (13). The present investigation was undertaken to provide a detailed characterization of cellulase from the locular tissues of ripening tomato fruits.…”