scholarly journals Pythium sulcatum and P. ultimum as causal agents of cavity spot disease of carrots in Egypt

2004 ◽  
Vol 84 (2) ◽  
pp. 607-614 ◽  
Author(s):  
K. A. El-Tarabily ◽  
M. A. Abouzeid ◽  
G. E. ST. J. Hardy ◽  
K. Sivasithamparam
Keyword(s):  
Cell Wall ◽  
Nile Delta ◽  
Pectate Lyase ◽  
Pectin Methylesterase ◽  
First Record ◽  
Cell Wall Degrading Enzymes ◽  
Spot Disease ◽  
Degrading Enzymes ◽  
Cavity Spot ◽  
Pathogenicity Tests

In a survey of carrot diseases of the Nile delta region of northern Egypt, Pythium sulcatum (Pratt and Mitchell) and P. ultimum (Trow) were isolated from 74 and 26%, respectively, of carrot roots showing cavity spot disease. In laboratory and glasshouse pathogenicity tests, P. sulcatum caused significantly (P < 0.05) more severe damage than P. ultimum. The greater level of pathogenicity of P. sulcatum was associated with its ability to produce a wider array of cell-wall-degrading enzymes with significantly (P < 0.05) higher enzymatic activities compared to P. ultimum. Polygalacturonase, pectin lyase, pectate lyase and cellulase were detected in cavity spot lesions induced by both P. sulcatum and P. ultimum. Pectin methylesterase was detected in tissues invaded by P. sulcatum and not by P. ultimum. This is the first record of cavity spot disease of carrots in Egypt and indicates P. sulcatum and P. ultimum as the causal agents of this disease in the region surveyed. Key words: Carrots, cavity spot, cell-wall-degrading enzymes, Egypt, Pythium

scholarly journals High-CO2 Treatment Prolongs the Postharvest Shelf Life of Strawberry Fruits by Reducing Decay and Cell Wall Degradation

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1649
Author(s):  
Hyang-Lan Eum ◽  
Seung-Hyun Han ◽  
Eun-Jin Lee
Keyword(s):  
Cell Wall ◽  
Shelf Life ◽  
Physiological Mechanism ◽  
Pectate Lyase ◽  
Pectin Methylesterase ◽  
Cell Wall Degradation ◽  
Cell Wall Degrading Enzymes ◽  
High Co2 ◽  
Genes Encoding ◽  
Co2 Treatment

Improved methods are needed to extend the shelf life of strawberry fruits. The objective of this study was to determine the postharvest physiological mechanism of high-CO2 treatment in strawberries. Harvested strawberries were stored at 10 °C after 3 h of exposure to a treatment with 30% CO2 or air. Pectin and gene expression levels related to cell wall degradation were measured to assess the high-CO2 effects on the cell wall and lipid metabolism. Strawberries subjected to high-CO2 treatment presented higher pectin content and firmness and lower decay than those of control fruits. Genes encoding cell wall-degrading enzymes (pectin methylesterase, polygalacturonase, and pectate lyase) were downregulated after high-CO2 treatment. High-CO2 induced the expression of oligogalacturonides, thereby conferring defense against Botrytis cinerea in strawberry fruits, and lowering the decay incidence at seven days after its inoculation. Our findings suggest that high-CO2 treatment can maintain strawberry quality by reducing decay and cell wall degradation.

Cell wall degrading enzymes in fusarium wilt of chickpea: correlation between pectinase and xylanase activities and disease development in plants infected with two pathogenic races of Fusarium oxysporum f. sp. ciceris

2006 ◽  
Vol 84 (9) ◽  
pp. 1395-1404 ◽  
Author(s):  
Inmaculada Jorge ◽  
Juan A. Navas-Cortés ◽  
Rafael M. Jiménez-Díaz ◽  
Manuel Tena
Keyword(s):  
Cell Wall ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Specific Activity ◽  
Gel Filtration ◽  
Pectate Lyase ◽  
Disease Development ◽  
In Planta ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes

Production of cell wall degrading enzymes (CWDEs) polygalacturonase (PG), pectate lyase (PL), and xylanase was studied in chickpeas ( Cicer arietinum L. ‘P-2245’) inoculated with Fusarium oxysporum f. sp. ciceris (Padwick) Matuo & K. Sato races 0 (mildly virulent, causing a yellowing syndrome) and 5 (highly virulent, causing a wilting syndrome) by the water-culture method. These CWDEs were similarly produced in both syndromes. PG and PL were the only enzymes occurring in roots and stems and attained the highest specific activity, this being generally higher for race 5 than for race 0. Gel filtration chromatography revealed a similar complement of in planta expressed pectinase isoforms, dominated by an endo-PG and two endo-PLs, the endo-PLs being differentially expressed by the two races. CWDE activities in roots and stems were positively correlated with development of yellowing and wilting. Exceptions to this were PG in stems, which was negatively correlated with the development of yellowing, and PG in roots, which showed a negative trend with development of either syndrome. The levels of CWDEs that significantly correlated with disease development were adequately described by exponential functions of disease progress. Results have implications for the role played by CWDEs in the early and later stages of pathogenesis in chickpea fusarium wilt.

Effect of the herbicide Pyradur on host cell wall degradation by the sugarbeet pathogens Rhizoctonia solani and Sclerotium rolfsii

1996 ◽  
Vol 74 (9) ◽  
pp. 1407-1415 ◽  
Author(s):  
Mohamed S. El-Abyad ◽  
Amira M. Abu-Taleb ◽  
Tarek Abdel-Mawgood
Keyword(s):  
Cell Wall ◽  
Rhizoctonia Solani ◽  
Sclerotium Rolfsii ◽  
Pectate Lyase ◽  
Inoculum Potential ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes ◽  
Alkaline Conditions

Pyradur applied to soil at 0.6–2.4 µg∙g−1 active ingredients suppressed infection of three sugarbeet cultivars by Rhizoctonia solani and Sclerotium rolfsii. In the absence of Pyradur, R. solani was more virulent than S. rolfsii against 'Raspoly' and 'TOP', whereas S. rolfsii was more virulent than R. solani against ‘Tribel’. Virulence was directly correlated with the activities of cell wall degrading enzymes produced by mese pathogens in vivo and on cell walls in vitro. Reduced virulence of R. solani and S. rolfsii under Pyradur stress was due to decreased inoculum potential of the two pathogens at the utilized concentrations of herbicide in situ and to reduced production of cell wall degrading enzymes in vitro and in host tissues. In addition, shifts in the pH of cell wall amended media, because of changes in the nature of metabolic products of the pathogens under Pyradur stress, suggest possible repression or stimulation of the activity of the enzymes involved in degradation in vivo, of which cellulase and polygalacturonase are favoured by acid conditions, and galactanase, mannase, and pectate lyase are favoured by alkaline conditions. Keywords: sugarbeet, Rhizoctonia solani, Sclerotium rolfsii, Pyradur, metolachlor, chloridazon, growth activities, pathogenicity, virulence, cell wall enzymes.

scholarly journals The Necrotrophic Fungus Macrophomina phaseolina Promotes Charcoal Rot Susceptibility in Grain Sorghum Through Induced Host Cell-Wall-Degrading Enzymes

2018 ◽  
Vol 108 (8) ◽  
pp. 948-956 ◽  
Author(s):  
Y. M. A. Y. Bandara ◽  
D. K. Weerasooriya ◽  
S. Liu ◽  
C. R. Little
Keyword(s):  
Cell Wall ◽  
Glycosyl Hydrolase ◽  
Pectin Methylesterase ◽  
Macrophomina Phaseolina ◽  
Grain Sorghum ◽  
Cell Wall Degrading Enzymes ◽  
Charcoal Rot ◽  
Degrading Enzymes ◽  
Encoding Genes ◽  
Polygalacturonase Activity

The cell-wall-degrading enzymes (CWDE) secreted by necrotrophs are important virulence factors. Although not unequivocally demonstrated, it has been suggested that necrotrophs induce hosts to cooperate in disease development through manipulation of host CWDE. The necrotrophic fungus Macrophomina phaseolina causes charcoal rot disease in Sorghum bicolor. An RNA-seq experiment was conducted to investigate the behavior of sorghum CWDE-encoding genes after M. phaseolina inoculation. Results revealed M. phaseolina’s ability to significantly upregulate pectin methylesterase-, polygalacturonase-, cellulase-, endoglucanase-, and glycosyl hydrolase-encoding genes in a charcoal rot-susceptible sorghum genotype (Tx7000) but not in a resistant genotype (SC599). For functional validation, crude enzyme mixtures were extracted from M. phaseolina- and mock-inoculated charcoal-rot-resistant (SC599 and SC35) and -susceptible (Tx7000 and BTx3042) sorghum genotype stalks. A gel diffusion assay (pectin substrate) revealed significantly increased pectin methylesterase activity in M. phaseolina-inoculated Tx7000 and BTx3042. Polygalacturonase activity was determined using a ruthenium red absorbance assay (535 nm). Significantly increased polygalacturonase activity was observed in two susceptible genotypes after M. phaseolina inoculation. The activity of cellulose-degrading enzymes was determined using a 2-cyanoacetamide fluorimetric assay (excitation and emission maxima at 331 and 383 nm, respectively). The assay revealed significantly increased cellulose-degrading enzyme activity in M. phaseolina-inoculated Tx7000 and BTx3042. These findings revealed M. phaseolina’s ability to promote charcoal rot susceptibility in grain sorghum through induced host CWDE.

scholarly journals Possible Role of Colonization and Cell Wall-Degrading Enzymes in the Differential Ability of Three Ulocladium atrum Strains to Control Botrytis cinerea on Necrotic Strawberry Leaves

2001 ◽  
Vol 91 (11) ◽  
pp. 1030-1036 ◽  
Author(s):  
Philippe Berto ◽  
M. Haïssam Jijakli ◽  
Philippe Lepoivre
Keyword(s):  
Cell Wall ◽  
Botrytis Cinerea ◽  
Pectate Lyase ◽  
Fungal Cell Wall ◽  
Cell Wall Degrading Enzymes ◽  
Glucanase Activity ◽  
Fungal Cell ◽  
Degrading Enzymes ◽  
Complementary Role ◽  
Immunological Assays

Ulocladium atrum (strain 385) consistently reduced Botrytis cinerea sporulation on necrotic fragments of strawberry leaves. On these tissues, two strains of U. atrum (isolates 18558 and 18559) showed lower antagonistic activities than the reference strain 385. Colonization of strawberry leaflets by the three U. atrum strains appeared similar in the absence of B. cinerea, whether quantified by chitin or immunological assays. The second method (based on anti-U. atrum antibodies) revealed that strawberry leaflet colonization by U. atrum 385 was better than by the other U. atrum strains in the presence of B. cinerea. An immunoassay using anti-B. cinerea antibodies revealed that the colonization of B. cinerea in tissues was lower in the presence of U. atrum 385 than with the two other U. atrum strains. The enzymatic activities produced by U. atrum 385 during the colonization phases of necrotic tissues were compared to B. cinerea and U. atrum strains 18558 and 18559. U. atrum 385 had the highest lipase, pectate lyase, and cellobiase activities while B. cinerea had the highest endo-β-1,4-glucanase activity. The study of lytic activities hydrolyzing the fungal cell wall revealed higher β-1,3-glucanase activity with U. atrum 385, which was stimulated by B. cinerea on necrotic strawberry leaflets. These results suggest that plant and fungal cell wall-degrading enzymes produced by U. atrum 385 may play a complementary role in the competitive colonization of dead strawberry leaves against B. cinerea.

scholarly journals Pawpaw [Asimina triloba (L.) Dunal] Fruit Ripening. II. Activity of Selected Cell-wall Degrading Enzymes

2005 ◽  
Vol 130 (4) ◽  
pp. 643-648 ◽  
Author(s):  
Rumphan Koslanund ◽  
Douglas D. Archbold ◽  
Kirk W. Pomper
Keyword(s):  
Cell Wall ◽  
Pectin Methylesterase ◽  
Relative Increase ◽  
Fruit Firmness ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes ◽  
Asimina Triloba ◽  
Early Ripening ◽  
Cell Wall Disassembly ◽  
Tissue Prints

Pawpaw fruit were harvested at the advent of the ripening process and were ripened at room temperature. Based on fruit firmness and respiration and ethylene production rates at harvest and during ripening, fruit were classified into one of four categories: preripening (no to very slight loss of firmness; preclimacteric), early ripening (some softening; increasing rates of ethylene and CO2 production), mid-ripening (soft; at or just past climacteric), and late ripening (very soft; postclimacteric). The activities of the cell-wall degrading enzymes polygalacturonase (PG), endo-(1→4)ß-D-glucanase (EGase), and endo-ß-1,4-mannanase (MAN) were low in the preripening and early ripening stages, increased dramatically by mid-ripening coincident with the respiratory and ethylene climacterics, and decreased at late ripening. However, pectin methylesterase (PME) activity per milligram protein was highest at the green stage when the fruit firmness was high and decreased as ripening progressed. Tissue prints indicated both EGase and MAN increased as ripening proceeded. The EGase activity was evident near the seeds and the surface of the fruit at preripening and eventually spread throughout, while MAN activity was evident near the fruit surface at preripening and was progressively expressed throughout the flesh as fruit ripened. The greatest decline in fruit firmness occurred between pre- and early ripening, before the peak activities of PG, EGase, and MAN, although MAN exhibited the greatest relative increase of the three enzymes in this period. The data suggest that PME may act first to demethylate polygalacturonate and may be followed by the action of the other enzymes resulting in cell wall disassembly and fruit softening in pawpaw.

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