Developmental variation of cell wall degrading enzymes from cucumber (Cucumis sativus) fruit tissues

Abstract

Variation of cell wall degrading enzyme activities and tissue firmness from the petal senescence to overripe stages of fruit development was studied in greenhouse-grown cucumbers (Cucumis sativus L. cv. Heinz 3534). Cucumbers exhibited a typical sigmoidal growth curve with a short lag phase (0–8 days after pollination) and extended log phase (8–28 days) followed by a stationary phase. Mesocarp firmness decreased between 10 and 20 days after pollination, then increased until 32 days after pollination. This decrease of mesocarp firmness was accompanied by increased activity of cellulase (3.5-fold), polygalacturonase (20-fold), pectin methylesterase (4-fold), and xylanase (9-fold). By contrast, carpel tissue firmness declined from 8–20 days after pollination, and remained low until 32 days after pollination. Only polygalacturonase and xylanase activities exhibited significant increases (5- and 6-fold, respectively) during softening of this tissue. Further, these peaks of enzyme activity in the carpel occurred 10 days before the corresponding peaks in the mesocarp. These data suggest that mesocarp and carpel tissues of cucumber soften by similar, but not identical mechanisms.

Textural, histological and biochemical changes in cucumber (Cucumis sativus L) due to immersion and variations in turgor pressure

“…29 As pectic substances are involved in the textural characteristics of cucumbers, PG could play a major role in texture expression. 6,7,29,33,34 In our research, PG increased significantly (P < 0.05) in all equilibrated tissues in comparison with raw (unsoaked) cucumber. The higher value of PG activity might be a response to immersion-equilibration, and this increased activity might produce tissue alteration owing to the capacity of PG for cell wall pectin hydrolysis, especially considering that only 18% (AE1%) of pectin was methylated according to measurements performed in cell walls isolated from raw cucumber mesocarp tissue.…”

Potential Role of Native Pickling Cucumber Polygalacturonase in Softening of Fresh Pack Pickles

“…Activities ranged from 27.5 to 121.6 DPU/gfw/h and averaged 54.8 ± 32 DPU. Differences in PG activity between samples may have been due to different cultivars and stresses involved with harvesting and postharvest handling that affected PG‐gene induction and expression (Miller and others 1987; Hadfield and Bennett 1998; Kubo and others 2000).…”

“…Firmness of fresh pack cucumber ( Cucumis sativus ) pickle products gradually declines during storage, which adversely affects textural quality and market‐life. Although unproven, polygalacturonases (PG) (EC 3.2.1.15, endo‐PG; EC 3.2.1.67, exo‐PG) may contribute to gradual softening since low activities have been detected in raw immature cucumbers used for manufacturing pickle products (Bell 1951; Lampi and others 1958; Pressey and Avants 1975; Saltveit and McFeeters 1980; Miller and others 1987, 1989; Meurer and Gierschner 1992; Sajnin and others 2003). PG activities in pickling cucumbers were reported to increase due to stresses common in commercial operations such as mechanical injury (Miller and others 1987) and osmotic pressure (Sajnin and others 2003).…”

Effect of nanocellulose/chitosan composite coatings on cucumber quality and shelf life

“…Softening is an important parameter to determine the quality loss of fleshy fruits (Macro et al 2010). Cucumber contains many enzymes that are associated with tissue softening (Rashmi and Roger 2009),which were previously described by several investigators (Bell, Etchells, and Jones 1951;Pressey and Avants 1975;McFeeters, Bell, and Fleming 1980;Miller, Dalmasso, and Kretchman 1989;Mujer, Kretchman, and Miller 1991;Omran et al 1991). Various investigators have made efforts to inhibit this tissue softening phenomenon in order to provide beneficial consequences to the consuming human (Fasina and Fleming 2001;Fasina, Fleming, and Thompson 2002;Hurr et al 2013;Marcin, Richard, and Deborah 2015).…”