Frozen hydrated buds and epicarp of `Golden Delicious' apple (Malus domestica Borkh.) were observed with a low-temperature, field emission scanning electron microscope (SEM). In addition to observing surface features of these specimens, holders were modified to observe fractured specimens. A modified hinged holder retained both halves of a fractured specimen for examination of the complementary faces of frozen hydrated tissues. Low-temperature SEM avoided artifacts, such as extraction, solubilization, and shrinkage, which are normally encountered with chemical fixation, dehydration, and drying, respectively. The technique allowed observations of well-preserved frozen hydrated structures, such as the platelets of epicuticular wax; loosely associated organisms on plant surfaces, such as spider-mite eggs; delicate structures, such as fungal hyphae; and partially hydrated tissues, such as fruit epicarp and winter bud scales.
therefore the above explanation may also apply to sweet cherry. First, the bursting of cells as a consequence of excessive water uptake possibly through microcracks ( Glenn and Poovaiah, 1989 ; Peschel and Knoche, 2005 ) and of significant cell-wall
The plant cell wall is a highly organized structure composed of many different polysaccharides, proteins, and phenolic compounds. Fruit ripening involves extensive depolymerization of pectin, as well as other modifications to cell-wall components
throughout the province due to its high yield, good field performance, and strong adaptability. Fruit softening mainly results from cell wall degradation and the changes in cell wall composition, which are determined by a group of cell wall–modifying enzymes
). Regardless of the genetic mechanism of disease resistance, following exposure to a pathogen, most plants initiate gene expression changes (reviewed in Wise et al., 2007 ). Genes for proteins located in the plant cell wall and involved in plant defense
Prestorage infiltration of `Golden Delicious' apples (Malus domestica Borkh.) with calcium (Ca) retarded texture changes during storage at 0C and inhibited ethylene production of the fruit at 20C. Infiltration of the fruit with the polyamines (PA) putrescine (PUT) or spermidine (SPD) also altered texture changes, but did not inhibit ethylene production. When the fruit were treated with Ca first and then with PA, cell wall-hound Ca concentrations increased 4-fold, but PA levels in the cell wall increased only slightly. When the fruit were treated with PA first and then with Ca, PA levels in the cell wall increased 3-fold, but Ca concentration increased only 2-fold. These results indicate that Ca and PA may he competing for the same binding sites in the cell wall and that the improvement of fruit quality during storage by these cations could involve strengthening of the cell wall.
Crisosto, 2005 ; Robertson et al., 1990 ). Textural changes during peach fruit ripening are achieved by the concerted action of several cell wall modification enzymes ( Brummell et al., 2004 ; Hadfield and Bennett, 1998 ). Endo-polygalacturonase [endo
determinant of fruit quality traits such as accumulation of sugars and organic acids and the establishment of cell wall and cuticle characteristics ( Lemaire-Chamley et al., 2005 ; Mounet et al., 2009 ; Schlosser et al., 2008 ). Studies of tomato ( Solanum
.6 °F). Each treatment had four replicates; 1 mg·L −1 = 1 ppm, 1 mg·g −1 = 1000 ppm. Papaya fruit had a quadratic decrease in weight loss in response to increasing Ca concentrations at 4000 to 5400 mg·L −1 Ca ( Fig. 6A ). Ca may increase cell wall
., 2011 ). Loosening of the cell wall to increase plasticity and the presence of adequate turgor pressure are key factors that facilitate cell expansion ( Cosgrove et al., 2002 ). Cell wall extensibility is affected by multiple enzymes, including expansins