Cell Wall Enzymes and Cell Wall Changes in `Flavortop' Nectarines: mRNA Abundance, Enzyme Activity, and Changes in Pectic and Neutral Polymers during Ripening and in Woolly Fruit

Abstract

<jats:p>Most `Flavortop' nectarines [<jats:italic>Prunus persica</jats:italic> (L.) Batsch (Nectarine Group)] that were placed directly into 0 °C storage developed chilling injury after removal, while preconditioning fruit for 2 days at 20 °C (delayed storage) reduced chilling injury substantially. Chilling injury was expressed as the development of a dry, woolly flesh texture during ripening. Delayed-storage fruit were as firm as control fruit when placed in storage, but softened more during storage. Analysis of cell wall components showed that in woolly fruit a higher percentage of pectin was retained in the sodium carbonate fraction, although during ripening polymers in this fraction decreased in molecular mass (Mr). In the guanidine thiocyanate hemicellulose fraction of woolly fruit, the associated pectin and hemicellulose remained as large polymers, while in delayed-storage fruit they decreased in Mr during ripening. Endo-polygalacturonase (PG), pectin esterase (PE), and endo-glucanase (EGase) activities of delayed-storage fruit were the same as control fruit at the beginning of storage, although exo-PG was higher. However, differences were observed at the end of storage. Endo-PG activity was lower in control than delayed-storage fruit at the end of storage while PE activity was higher, and exo-PG and EGase activities were similar. These differences in activity were not reflected in the mRNA abundance of the respective enzymes. Endo-PG and PE message was similar in all fruit at the end of storage and increased during ripening, while EGase message was low at all times except in control fruit after storage and development of woolliness. Prevention of chilling injury by delayed storage appears to be due to the ability of the fruit to continue a progressive, slow cell wall degradation in storage which allows normal ripening to proceed when the fruit are rewarmed. Regulation of the softening process did not appear to be by enzyme synthesis, since mRNA levels of the enzymes did not correspond with enzyme activity.</jats:p>

Quality attributes and cell wall properties of strawberries (Fragaria annanassa Duch.) under calcium chloride treatment

“…Cell wall materials (CWM) were extracted in triplicate with each sampling (10 fruits per extraction) according to the method of Zhou et al (2000). Fresh peeled flesh (10 g) was ground before being boiled three times in ethanol (80%, v/v) (Tianjin Resent Chemical Co. Ltd., China) for 20 min; then ethanol was decanted by filtration, and the solid residue was transferred to 50 ml of dimethyl sulphoxide (DMSO, Tianjin Resent Chemicals Co. Ltd., China): H 2 O (9:1, v/v) for 12 h at 4°C.…”

Negative electrospray ionization mass spectrometry: a method for sequencing and determining linkage position in oligosaccharides from branched hemicelluloses

“…Recently, capillary electrophoresis (CE) was performed on labeled XylGos which were identified and characterized by coupling this electrophoretic system to an ESI‐ mass spectrometer . The main advantages of ESI‐MS technology are its sensitivity and its capability to assign linkage sequence and branching or substituent pattern information upon collision‐induced dissociation (CID) of underivatized oligosaccharides . Positive ESI‐MS/MS was applied for the structural analysis of XylG from seeds of H. courbaril , of black currants, of bilberries and of Arabidopsis leaves .…”

“…[33] The main advantages of ESI-MS technology are its sensitivity and its capability to assign linkage sequence and branching or substituent pattern information upon collision-induced dissociation (CID) of underivatized oligosaccharides. [44][45][46][47][48] Positive ESI-MS/MS was applied for the structural analysis of XylG from seeds of H. courbaril, of black currants, of bilberries and of Arabidopsis leaves. [15,18,33,49] However, the spectral information delivered from underivatized oligosaccharides, such as linkage position and substituent pattern information, is generally considered less informative than in negative-ion mode or by alkali metal cationization.…”

Proteomics in Food Biotechnology

“…Mealiness has been associated with pectin methylesterase (PME) activity that was reduced (Buescher and Furmanski 1978), increased (Ben-Arie and Sonego 1980), or unchanged Carroll 2000, Zhou et al 2000c). Similarly, mealy fruit had reduced exo-polygalacturonase (exo-PG) activity in some studies (Zhou et al 2000c), but not in others (Artes et al 1996). Reduced endo-PG activity during cold storage is commonly observed (Artes et al 1996), although mealiness develops not in cold storage but during subsequent ripening at warm temperatures (Buescher and Furmanski 1978).…”