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Cobra-Like4 ), and several α-type expansin ( MdEXPA ) genes putatively involved in the loosening of cell walls, was investigated ( Fig. 5 ). MdCOB1 expression in the shaded fruit was slightly higher (1.2-fold) at 0 d after treatment and was 1.6-fold
( Brüggenwirth and Knoche, 2016c ). However, a second factor may be the absence of cell wall swelling when cracking is the result of the mechanical straining of an excised skin or the perfusion of an intact fruit (M. Brüggenwirth, unpublished data). Importantly
holds the flesh under pressure in analogy with the turgor of an individual cell ( ) generated by the strained and stressed cell wall. Thus, the stimulates ingress of water, whereas the pressures and work in opposition to one another and tend to
Giovannoni, 2008 ), responsible for the definition of cell wall structure ( Hayama et al., 2006a ; Trainotti et al., 2003 ). Among these genes, a pivotal role is played by endo-polygalacturonase ( Brummell et al., 2004 ; Orr and Brady, 1993 ; Pressey and
phylogenetic tree created using the neighbor-joining method in MEGA5.05 was generated using amino acid sequences encoding SAIs and cell-wall invertases (CWIs) from Rhododendron and other plants ( Fig. 5 ) Plant invertase sequences, regardless of their origins
Abstract
Scald was the major grade lowering defect resulting from mechanical harvesting of sour cherries for processing. Histological sections of scalded tissue showed no crushing or distortion of cells, but the epidermal cells appeared dense and the cell walls appeared to be thicker than those of nonscalded tissue. Since the cells of scalded tissue did not appear distorted, bruising apparently induced a chemical change as a result of membrane disruption bringing about discoloration. Microscopic examination indicated that darkened bruises on the epidermis of the cherries occurred prior to mechanical harvesting. Tannins were located primarily in the epidermal region, but during a 24-hour soak there was a slight movement of tannin into the outer cortical cells. Greater movement occurred in mechanically harvested cherries than in handpicked fruit. The cellular disruption resulting from bruising by mechanical harvesting possibly aided the movement of tannins. Scald was a major grade lowering factor when mechanically harvested cherries were soaked longer than 8 hours before processing.
Abstract
Succinic acid 2,2-dimethyl hydrazide (Alar) 2 was applied as 3 weekly foliar sprays at concentrations of 0, 1000, and 2000 ppm to ‘Sovereign’, an Fj cultivar of Tagetes erecta L., grown in a complete nutrient supply under long and short day photoperiods. Plants were sampled for anatomical study one week later. Treated plants grown under long days had thicker leaves and a larger root diameter. In short days, the capitula of treated plants were one-half the size of the untreated ones. The amount of phloem fibers in treated plants was less and cortical and pith cells were shorter in both photoperiods. Alar affected cell wall formation and the phloem fibers in the stems were thinner walled and less sclerified.
Abstract
Aphelandra squarrosa Nees. plants grown under 250 μmol s−lm−2 photosynthetically active radiation (PAR) were transferred to 265, 737, and 1070 μmol s−1m−2. Stomatal density and number of palisade layers of newly expanded leaves decreased linearly after 2 months, while number of countable chloroplasts per palisade cell increased linearly as light intensity decreased. Number of countable chloroplasts per palisade cell decreased and palisade layers increased in mature leaves transferred to higher PAR levels. Stomatal density and guard cell length in mature leaves did not change. There were nonlinear responses to PAR levels in number of marginal collenchyma cells, leaf thickness, and palisade cell length of immature leaves. Chloroplasts in mature and immature leaves were less discrete and more tightly appressed to anticlinal palisade cell walls as PAR levels increased.
Abstract
Anatomical changes which take place in conjunction with abscission of cantaloupe fruits (Cucumis melo L. cv. Powdery Mildew Resistant No. 45) include cell separation and cell collapse. Structural modifications in abscission zone cell walls are accompanied by histochemical changes which include losses of pectins and insoluble polysaccharides. Development of a separation cavity is consistently correlated with physiologically defined stages of fruit maturity, and the time of abscission coincides with the peak of the respiratory climacteric. Anatomical and histochemical changes similar to those in cantaloupe also take place in honeydew fruits (Cucumis melo L. cv. Honeydew). However, the abscission zone of honeydews is not structurally well defined, changes are limited to certain parenchyma cells, and the honeydew fruits do not normally abscise. It is suggested that the most desirable growth regulator for use on cantaloupes to accelerate and unify the time of fruit ripening would be one which did not coincidentally accelerate abscission.
Abstract
Hardcore was apparent in cooked sweet potatoes (Ipomoea batatas Lam.) which had been chilled and transferred to nonchilling temperatures prior to cooking. The severity increased with duration of chilling at 2°C. Hardcore was not observed in roots boiled immediately after chilling, although these roots were firmer than those not chilled. Enhanced levels of pectic substances, soluble in sodium hexametaphosphate, were associated with hardcore tissue, while starch, protopectin, and hemicellulose were related to enhanced firmness of continuously chilled roots. No differences in pectinmethylesterase activity were observed between storage treatments. Reduced levels of alpha amylase activity in continuously chilled roots probably accounted for the enhanced levels of starch after the roots were processed. From data on U.V. absorption, phenolic levels, and electrolyte leakage, we believe that hardcore develops when phenolics or related substances, and possibly cations, bind with cell wall materials.