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PubMed2003

The pH signalling transcription factor PacC controls virulence in the plant pathogen Fusarium oxysporum.

Gene expression in fungi by ambient pH is regulated via a conserved signalling cascade whose terminal component is the zinc finger transcription factor PacC/Rim1p. We have identified a pacC orthologue in the vascular wilt pathogen Fusarium oxysporum that binds the consensus 5'-GCCAAG-3' sequence and is proteolytically processed in a similar way to PacC from Aspergillus nidulans. pacC transcript levels were elevated in F. oxysporum grown in alkaline conditions and almost undetectable at extreme acidic growth conditions. PacC+/- loss-of-function mutants displayed an acidity-mimicking phenotype resulting in poor growth at alkaline pH, increased acid protease activity and higher transcript levels of acid-expressed polygalacturonase genes. Reintroduction of a functional pacC copy into a pacC+/- mutant restored the wild-type phenotype. Conversely, F. oxysporum merodiploids carrying a dominant activating pacCc allele had increased pacC transcript and protein levels and displayed an alkalinity-mimicking phenotype with reduced acid phosphatase and increased alkaline protease activities. PacC+/- mutants were more virulent than the wild-type strain in root infection assays with tomato plants, whereas pacCc strains were significantly reduced in virulence. We propose that F. oxysporum PacC acts as a negative regulator of virulence to plants, possibly by preventing transcription of acid-expressed genes important for infection.

Alleles↗

PubMed2004

Inhibition of phosphoinositide-specific phospholipase C results in the induction of pathogenesis-related genes in soybean.

The inositol 1,4,5-trisphosphate (IP3) content is decreased in soybean cells following infection with Pseudomonas syringae pv. glycinea (Psg). In this investigation, a differential display approach was applied to isolate soybean genes that are transcriptionally up-regulated by the inhibition of phosphoinositide-specific phospholipase C (PI-PLC) activity and to study if the transcription of those genes is altered following Psg infection. Four genes, transcriptionally activated following treatment with the PI-PLC-specific inhibitor U-73122, were cloned. Three of the four genes were induced following infection with Psg. The transcripts of a hydrolase homologue (GmHy) were induced in the incompatible but not compatible soybean-Psg interaction. The transcripts of a putative ascorbate oxidase gene (GmAO) were induced in both compatible and incompatible interactions. GmHy and GmAO may represent new classes of pathogenesis-related genes. In addition to these two novel genes, homologues of PR-10 and polygalacturonase inhibitor protein (GmPR10 and GmPGIP, respectively) were identified. These two genes have previously been reported as pathogenesis-related. Transcripts of GmPR-10, but not GmPGIP, were induced in both compatible and incompatible soybean-Psg interactions. Induction of these genes, except for GmPGIP, following inhibition of PI-PLC by either the U-73122 treatment or bacterial infection suggests that PI-PLC may negatively regulate the expression of defence genes.

Amino Acid Sequence↗

PubMed1996

Detection and tissue distribution of anti-ulcer pectic polysaccharides from Bupleurum falcatum by polyclonal antibody.

Anti-sera against the "ramified" region (PG-1) of an anti-ulcer polysaccharide (bupleuran 2IIc), which was purified from the roots of Bupleurum falcatum L, were obtained by immunization of rabbits, and a polyclonal anti-bupleuran 2IIc/PG-1-antibody of the IgG class was purified by Protein G and "ramified" region (PG-1) immobilized affinity chromatographies. The antigenic specificity of anti-bupleuran 2IIc/PG-1-IgG was examined by a two-site sandwich ELISA which was developed as an improved method for microanalysis of bupleuran 2IIc using a biotinylated antibody. Another pectin from B. falcatum and anti-complementary pectins from Angelica acutilaba and Glycyrrhiza uralensis also showed significant reactivity to anti-bupleuran 2IIc/PG-1-IgG, although these reactivities were lower than that of bupleuran 2IIc. Other polysaccharides tested such as apple pectin, araban, yeast mannan, pullulan, etc., had negligible reactivity. The KDO-containing region and oligogalacturonides, which were obtained by endo-alpha-(1-->4)-polygalacturonase digestion of bupleuran 2IIc, were also not significantly recognized by anti-bupleuran 2IIc/PG-1-IgG. When bupleuran 2IIc was administered to the mice i.v., the polysaccharide disappeared from the circulation within 24 h and was mainly detected in the liver by the two-site sandwich ELISA. However the clearance of bupleuran 2IIc from the circulation was delayed by pretreatment with iota-carrageenan. When the crude polysaccharide fraction (BR-2), containing mainly bupleurans 2IIb and 2IIc from B.falcatum, was administrated orally to the mice, the polysaccharides were detected in the liver and Peyer's patch.

Animals↗

PubMed1994

Polyclonal antibody against a complement-activating pectin from the roots of Angelica acutiloba.

Anti-sera against a complement-activating pectin (AR-2IIb), which was purified from the roots of Angelica acutiloba Kitagawa, were obtained by immunization of rabbits, and a polyclonal anti-AR-2IIb antibody of the IgG class was purified by affinity chromatography on AR-2IIb-immobilized Sepharose and Protein G-Sepharose. Periodate oxidation of AR-2IIb significantly reduced its inhibitory activity on the reactivity of AR-2IIb to anti-AR-2IIb-IgG, but pronase digestion of AR-2IIb did not affect its inhibitory activity. Other pharmacologically active pectins from A. autiloba, Bupleurum falcatum, and Glycyrrhiza uralensis and the complement-activating pectic arabinogalactan from A. autiloba also showed significant inhibitory activities on the reactivity of AR-2IIb to anti-AR-2IIb-IgG, but these inhibitory activities were lower than that of AR-2IIb. Other pectins, polygalacturonic acid, arabinogalactan, galactan, and araban tested had negligible inhibitory activity. Endo-a-(1-->4)-polygalacturonase digestion of AR-2IIb indicated that its "ramified" region (rhamnogalacturonan core possessing neutral oligosaccharide side-chains) contained epitopes for anti-AR-2IIb-IgG, but that 2-keto-3-deoxyoctulosonic acid (KDO)-containing regions and oligogalacturonides obtained from AR-2IIb were not recognized by anti-AR-2IIb-IgG. Although carboxyl-reduction of galacturonic acid in the "ramified" region decreased the inhibitory activity of the "ramified" on its reactivity to anti-AR-2IIb, an acidic tetrasaccharide unit in the rhamnogalacturonan core had negligible inhibitory activity.

Animals↗

PubMed1994

Existence of a rhamnogalacturonan II-like region in bioactive pectins from medicinal herbs.

Unusual component sugars such as 2-methylfucose (2-Me-Fuc), 2-methylxylose (2-Me-Xyl), apiose (Api), and aceric acid (AceA) are contained in the bioactive pectins from Bupleurum falcatum, Glycyrrhiza uralensis, and Angelica acutiloba, but not in the other bioactive pectic heteroglycans and arabinogalactans from Chinese and Japanese herbs tested. Each pectin was digested with endo-alpha-(1-->4)-polygalacturonase, and gave two enzyme-resistant fractions, PG-1 (rhamnogalacturonan core with neutral sugar side-chains) and PG-2, and an oligogalacturonide fraction (PG-3) by gel filtration on Bio-gel P-30. The PG-2 fractions commonly consisted of unusual sugars such as 2-Me-Fuc, 2-Me-Xyl, Api, AceA, 3-deoxy-D-lyxo-heptulosaric acid (Dha), and 3-deoxy-D-manno-2-octulosonic acid (Kdo) in addition to Rha, Fuc, Ara, Xyl, Man, Gal, Glc, GalA, and GlcA. Lithium degradation of each PG-2 gave a pentosyl-->6-deoxyhexosyl-->6-deoxyhexosyl-->pentitol fragment as a major oligosaccharide in addition to some neutral di- to trisaccharide alditols. Methylation analysis of the lithium degradation products from each PG-2 also indicated that these oligosaccharide alditols mainly consisted of terminal Rha, Araf, Fuc, Xyl, and Gal, 4-linked Rha, 3-linked Fuc, and 3'-linked Api. HPLC analysis showed that PG-2 had molecular heterogeneity. These results indicate that the bioactive pectins from medicinal herbs commonly consist of the minor KDO-containing region which resembles the rhamnogalacturonan II in plant cell walls.

Carbohydrate Sequence↗

PubMed1991

Characterization of mitogenic pectic polysaccharides from kampo (Japanese herbal) medicine "juzen-taiho-to".

The acidic polysaccharide fraction (F-5-2) from "Juzen-Taiho-To" (TJ-48), a Kampo (Japanese herbal) medicine prepared by decocting a prescription of 10 kinds of herbs, has potent mitogenic activity. In order to clarify the mitogenic activity, F-5-2 was fractionated by amon-exchange chromatography, and 14 acidic polysaccharide fractions were obtained. Mitogenic activities of these polysaccharides were increasing with their molecular masses and affinities to the anion-exchange column. Methylation analysis and endo-alpha-(1----4)-polygalacturonase digestion showed these polysaccharide fractions to be pectic polysaccharides, many of which consisted mainly of polygalacturonan regions in addition to small amounts of "ramified" regions. Gel filtration showed that the molecular masses of the "ramified" regions of the polysaccharides were similar. High molecular mass polygalacturonic acid showed a weak mitogenic activity. The mitogenic (M-1 and M-2) and non-mitogenic (M-3) polysaccharides from the most active polysaccharide fraction (F-5-2IIh) were further purified by gel filtration. M-2 and M-3 were also shown to be pectic polysaccharides, and the neutral glycosidic linkages in M-2 and M-3 were different from each other. Endopolygalacturonase digestion markedly decreased the mitogenic activity of M-2, however, the "ramified" region of M-2 still showed a weak activity.

Animals↗

PubMed1991

Purification of anti-ulcer polysaccharides from the roots of Bupleurum falcatum.

A water-soluble crude polysaccharide fraction (BR-1) prepared from the root of Bupleurum falcatum L. (Japanese name = Saiko) prevented HCl/ethanol induced ulcerogenesis in mice significantly. BR-1 was fractionated into four polysaccharide fractions (BR-2, BR-3, BR-4, and BR-5) by the addition of cetyltrimethylammonium bromide, and the strongly acidic polysaccharide fraction BR-2 showed the most potent inhibition of gastric lesion formation. When BR-2 was further fractionated by anion-exchange chromatography, the most potent anti-ulcer activity was observed in the pectin-like polysaccharide, bupleuran 2IIc. Bupleuran 2IIc was homogeneous as determined by electrophoresis and gel filtration. Bupleuran 2IIc was composed mainly of galacturonic acid with small proportions of arabinose, rhamnose, and galactose, and its average relative molecular mass was estimated to be 63,000 d. BR-2 lost most of its activity after treatment with periodate or digestion with endo-polygalacturonase indicating that the polygalacturonan region and/or the molecular mass may contribute to activity.

Animals↗

PubMed1992

Purification of an anti-ulcer polysaccharide from the leaves of Panax ginseng.

Water-soluble and alkaline-soluble crude polysaccharides which were separated from the roots or leaves of Panax ginseng C. A. Meyer, were compared for their anti-ulcer activity. Of these four polysaccharide fractions, the water-soluble crude polysaccharide fraction (GL-2) from the leaves and the alkaline-soluble crude polysaccharide fraction (GRA-2) from the roots prevented HCl/ethanol-induced ulcerogenesis in mice potently. The most potent fraction, GL-2, was further fractionated into four polysaccharide fractions by precipitation with cethyltrimethylammonium bromide, and the weakly acidic polysaccharide fraction, GL-4, showed the most potent inhibition of gastric lesion formation. The activity of GL-4 decreased after treatment with periodate or digestion with endo-polygalacturonase, indicating that the carbohydrate moiety may contribute to the expression of the activity. GL-4 was further purified by anion-exchange chromatography and gel filtration, and the most active purified polysaccharide, GL-4IIb1III was obtained. GL-4IIb1III (average relative molecular mass, 16,000 d) had the nature of a pectic polysaccharide, and was composed mainly of galactose and galacturonic acid with small proportions of rhamnose, arabinose, mannose, glucose, and glucuronic acid. GL-4IIIb1III prevented HCl/ethanol-induced ulcerogenesis in mice dose dependently.

Animals↗

PubMed2000

Pectin engineering: modification of potato pectin by in vivo expression of an endo-1,4-beta-D-galactanase.

Potato tuber pectin is rich in galactan (oligomer of beta-1,4-linked galactosyl residues). We have expressed a fungal endo-galactanase cDNA in potato under control of the granule bound starch synthase promoter to obtain expression of the enzyme in tubers during growth. The transgenic plants displayed no altered phenotype compared with the wild type. Fungal endo-galactanase activity was quantified in the transgenic tubers, and its expression was verified by Western blot analysis. The effect of the endo-galactanase activity on potato tuber pectin was studied by Fourier transform infrared microspectroscopy, immuno-gold labeling, and sugar analysis. All analyses revealed alterations in pectin composition. Monosaccharide composition of total cell walls and isolated rhamnogalacturonan I fragments showed a reduction in galactosyl content to 30% in the transformants compared with the wild type. Increased solubility of pectin from transgenic cell walls by endo-polygalacturonase/pectin methylesterase digestion points to other changes in wall architecture.

Genetic Engineering↗

PubMed2002

Evaluation of transgenic tomato plants expressing an additional phytoene synthase in a fruit-specific manner.

Phytoene synthase from the bacterium Erwinia uredovora (crtB) has been overexpressed in tomato (Lycopersicon esculentum Mill. cv. Ailsa Craig). Fruit-specific expression was achieved by using the tomato polygalacturonase promoter, and the CRTB protein was targeted to the chromoplast by the tomato phytoene synthase-1 transit sequence. Total fruit carotenoids of primary transformants (T(0)) were 2-4-fold higher than the controls, whereas phytoene, lycopene, beta-carotene, and lutein levels were increased 2.4-, 1.8-, and 2.2-fold, respectively. The biosynthetically related isoprenoids, tocopherols plastoquinone and ubiquinone, were unaffected by changes in carotenoid levels. The progeny (T(1) and T(2) generations) inherited both the transgene and phenotype. Determination of enzyme activity and Western blot analysis revealed that the CRTB protein was plastid-located and catalytically active, with 5-10-fold elevations in total phytoene synthase activity. Metabolic control analysis suggests that the presence of an additional phytoene synthase reduces the regulatory effect of this step over the carotenoid pathway. The activities of other enzymes in the pathway (isopentenyl diphosphate isomerase, geranylgeranyl diphosphate synthase, and incorporation of isopentenyl diphosphate into phytoene) were not significantly altered by the presence of the bacterial phytoene synthase.

Alkyl and Aryl Transferases↗

PubMed1981

Proteinase inhibitor-inducing factor activity in tomato leaves resides in oligosaccharides enzymically released from cell walls.

The synthesis and accumulation of proteinase inhibitor I in excised tomato leaves can be induced with oligosaccharides obtained by fungal endo-alpha-1,4-polygalacturonase digestion of a pectic polysaccharide (M(r) 5000-10,000) isolated from tomato leaves. Active oligosaccharides were also released from isolated tomato leaf cell walls by endopolygalacturonases partially purified from tomato plants. It is suggested that oligosaccharides, released from plant cell wall pectic polysaccharides by either endogenous or exogenous endopolygalacturonases at a wound or infection site, may have hormone-like roles in regulating plant defense responses in unwounded tissues many centimeters away from the site of release.

Journal Article↗

PubMed1990

Laticifer-specific gene expression in Hevea brasiliensis (rubber tree).

Natural rubber, cis-1,4-polyisoprene, is obtained from a colloidal fluid called latex, which represents the cytoplasmic content of the laticifers of the rubber tree (Hevea brasiliensis). We have developed a method of extracting translatable mRNA from freshly tapped latex. Analysis of in vitro translation products of latex mRNA showed that the encoded polypeptides are very different from those of leaf mRNA and these differences are visible in the protein profiles of latex and leaf as well. Northern blot analysis demonstrated that laticifer RNA is 20- to 100-fold enriched in transcripts encoding enzymes involved in rubber biosynthesis. Plant defense genes encoding chitinases, pathogenesis-related protein, phenylalanine ammonia-lyase, chalcone synthase, chalcone isomerase, cinnamyl alcohol dehydrogenase, and 5-enolpyruvylshikimate-3-phosphate synthase show a 10- to 50-fold higher expression in laticifers than in leaves, indicating the probable response of rubber trees to tapping and ethylene treatment. Photosynthetic genes encoding ribulose-bisphosphate carboxylase small subunit and chlorophyll a/b-binding protein are not expressed at a detectable level in laticifers. In contrast, genes encoding two hydrolytic enzymes, cellulase and polygalacturonase, are more highly expressed in laticifers than in leaves. Transcripts for the cytoplasmic form of glutamine synthase are preferentially expressed in laticifers, whereas those for the chloroplastic form of the same enzyme are present mainly in leaves. Control experiments demonstrated that beta-ATPase, actin, and ubiquitin are equally expressed in laticifers and leaves. Therefore, the differences in specific transcript abundance between laticifers and leaves are due to differential expression of the genes for these transcripts in the laticifers.

Journal Article↗

PubMed1998

The promoter of LE-ACS7, an early flooding-induced 1-aminocyclopropane-1-carboxylate synthase gene of the tomato, is tagged by a Sol3 transposon.

Many terrestrial plants respond to flooding with enhanced ethylene production. The roots of flooded plants produce 1-aminocyclopropane-1-carboxylic acid (ACC), which is transported from the root to the shoot, where it is converted to ethylene. In the roots, ACC is synthesized by ACC synthase, which is encoded by a multigene family. Previously, we identified two ACC synthase genes of tomato that are involved in flooding-induced ethylene production. Here, we report the cloning of LE-ACS7, a new tomato ACC synthase with a role early during flooding but also in the early wound response of leaves. The promoter of LE-ACS7 is tagged by a Sol3 transposon. A Sol3 transposon is also present in the tomato polygalacturonase promoter to which it conferred regulatory elements. Thus, Sol3 transposons may affect the regulation of LE-ACS7 and may be involved in the communication between the root and the shoot of waterlogged tomato plants.

Amino Acid Sequence↗

PubMed2006

Crucial role of antioxidant proteins and hydrolytic enzymes in pathogenicity of Penicillium expansum: analysis based on proteomics approach.

Penicillium expansum, a widespread filamentous fungus, is a major causative agent of fruit decay and may lead to the production of mycotoxin that causes harmful effects on human health. In this study, we compared the cellular and extracellular proteomes of P. expansum in the absence and presence of borate, which affects the virulence of the fungal pathogen. The differentially expressed proteins were identified using ESI-Q-TOF-MS/MS. Several proteins related to stress response (glutathione S-transferase, catalase, and heat shock protein 60) and basic metabolism (glyceraldehyde-3-phosphate dehydrogenase, dihydroxy-acid dehydratase, and arginase) were identified in the cellular proteome. Catalase and glutathione S-transferase, the two antioxidant enzymes, exhibited reduced levels of expression upon exposure to borate. Because catalase and glutathione S-transferase are related to oxidative stress response, we further investigated the reactive oxygen species (ROS) levels and oxidative protein carbonylation (damaged proteins) in P. expansum. Higher amounts of ROS and carbonylated proteins were observed after borate treatment, indicating that catalase and glutathione S-transferase are important in scavenging ROS and protecting cellular proteins from oxidative damage. Additionally to find secretory proteins that contribute to the virulence, we studied the extracellular proteome of P. expansum under stress condition with reduced virulence. The expression of three protein spots were repressed in the presence of borate and identified as the same hydrolytic enzyme, polygalacturonase.

Antioxidants↗

PubMed2002

Inhibition of hydrolytic enzyme activities and plant pathogen growth by invertase inhibitors.

The invertase inhibitory protein isolated from Cyphomandra betacea Sendt and Solanum tuberosum inhibited the invertase activity from different species, genera and even plant family. Furthermore, proteinaceous inhibitors are not invertase specific; fungal, bacterial and higher plant enzymes including polygalacturonase, pectinase, pectin lyase, alpha-L-arabinofuranosidase and beta-glucosidase are also shown to be inhibited. Both inhibitors exhibited an in vitro antibacterial action against phytopathogenics strains of Xanthomonas campestris pvar vesicatoria CECT 792, Pseudomonas solanacearum CECT 125, Pseudomonas corrugata CECT 124, Pseudomonas syringae and Erwinia carotovora var carotovora.

Enzyme Inhibitors↗

PubMed1999

Biochemical characteristics of non starch polysaccharide hydrolyzing enzyme preparations designed as feed additives for poultry and piglet nutrition.

Non starch polysaccharide hydrolyzing enzyme preparations analyzed in this study were composed of up to nine (1-3, 1-4)-beta-glucanase activities and up to six xylanase activities with different molecular weights in the range from 100 kD down to 18 kD as determined with SDS/PAGE zymograms. Partially purified enzyme fractions differed in terms of pH-optima, isoelectric point and thermal stability in aquaeous solutions. Different beta-glucanase activities were found in different production strains, although some enzymes were conserved over genus boundaries. Enzyme preparations from the same or related strains exhibited different patterns of enzyme activity, indicating modification of strain and/or fermentation conditions. Some enzyme preparations contained significant amounts of polygalacturonase and/or galactomannase activity. The pH profiles of whole enzyme preparations resulted from pH optima of isoenzyme fractions. Temperature optima for all preparations were between 50 and 60 degrees C. Thermal stability of high molecular weight components tended to be lower than for low molecular weight fractions. Fractions with cellulase activity were most stable, followed by (1-3, 1-4)-beta-glucanase activities, while fractions with xylanase activities exhibited low thermal stabilities. Incubation of enzyme preparations and their respective active fractions in digesta supernatants revealed only small differences in residual xylanase activity. Digesta from gizzard samples led to the highest inactivation. It is concluded that commercial enzyme preparations display different modes of action and that the development of improved enzyme preparations depends not only on thermal stability, but also on pH profile, substrate specificity and proteolytic stability within the digestive tract.

Animal Nutritional Physiological Phenomena↗

PubMed2004

Constitutive expression of EIL-like transcription factor partially restores ripening in the ethylene-insensitive Nr tomato mutant.

Climacteric fruit ripening is regulated by the phytohormone ethylene. ETHYLENE-INSENSITIVE3 (EIN3) is a transcription factor that functions downstream from the ethylene receptors in the Arabidopsis ethylene signal transduction pathway. Three homologues of the Arabidopsis EIN3 gene have been identified in tomato, Lycopersicon esculentum, EIN3-like or LeEIL, LeEIL1, LeEIL2, and LeEIL3. These transcription factors have been proposed to be functionally redundant positive regulators of multiple ethylene responses. In order to test the role of such factors in the ethylene signal transduction pathway during ripening, EIL1 fused to green fluorescent protein (GFP) has been over-expressed in the ethylene-insensitive non-ripening Nr mutant of tomato. Increased levels of LeEIL1 compensated for the normally reduced levels of LeEIL1 in the Nr mutant, and transgenic Nr plants that exhibited high-level constitutive expression of LeEIL1GFP phenotypically resembled wild-type plants, the fruit ripened and the leaves exhibited epinasty, unlike Nr plants. The EIL1GFP fusion protein was located in the cell nuclei of ripe tomato fruit. The mRNA profile of these plants showed that the expression of certain ethylene-dependent ripening genes was up-regulated, including polygalacturonase and TOMLOX B. However, not all ripening genes and ethylene responses, such as seedling triple response, were restored. These results demonstrate that expressing candidate genes in the Nr ethylene-insensitive background is a valuable general approach for testing the role of putative downstream components in the ethylene-signalling pathway.

Arabidopsis Proteins↗

PubMed2004

Cell wall metabolism during maturation, ripening and senescence of peach fruit.

Cell wall changes were examined in fruit of a melting flesh peach (Prunus persica L.) allowed to ripen on the tree. Three phases to softening were noted, the first of which began prior to the completion of flesh colour change and an increase in ethylene evolution. Softening in young mature fruit, prior to ripening, was associated with a depolymerization of matrix glycans both loosely and tightly attached to cellulose and a loss of Gal from all cell wall fractions. After the initiation of ripening, but before the melting stage, softening was associated with continuing, progressive depolymerization of matrix glycans. A massive loss of Ara from the loosely bound matrix glycan fraction was observed, probably from side chains of glucuronoarabinoxylan, pectin, or possibly arabinogalactan protein firmly bound into the wall and solubilized in this extract. An increase in the solubilization of polyuronides also occurred during this period, when softening was already well advanced. The extensive softening of the melting period was marked by substantial depolymerization of both loosely and tightly bound matrix glycans, including a loss of Ara from the latter, an increase in matrix glycan extractability, and a dramatic depolymerization of chelator-soluble polyuronides which continued during senescence. Depolymerization of chelator-soluble polyuronides thus occurred substantially after the increase in their solubilization. Ripening-related increases were observed in the activities of exo- and endo-polygalacturonase (EC 3.2.1.67; EC 3.2.1.15), pectin methylesterase (EC 3.1.1.11), endo-1,4-beta-glucanase (EC 3.2.1.4), endo-1,4-beta-mannanase (EC 3.2.1.78), alpha-arabinosidase (EC 3.2.1.55), and beta-galactosidase (EC 3.2.1.23), but the timing and extent of the increases differed between enzymes and was not necessarily related to ethylene evolution. Fruit softening in peach is a continuous process and correlated closely with the depolymerization of matrix glycans, which proceeded throughout development. However, numerous other cell wall changes also took place, such as the deglycosylation of particular polymers and the solubilization and depolymerization of chelator-soluble polyuronides, but these were transient and occurred only at specific phases of the softening process. Fruit softening and other textural changes in peach appear to have a number of stages, each involving a different set of cell wall modifications.

Aging↗