Studies on the Infection of Onion Plants by Sclerotium cepivorum Berk.

Abd-Elrazik, A. A.; Shatla, M.N.; Rushdi, M. H.

doi:10.1111/j.1439-0434.1973.tb02649.x

Cited by 27 publications

(14 citation statements)

References 7 publications

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“…S. cepivorum sclerotia produce mycelium in response to the presence of Allium root exudates (Coley‐Smith & Holt, 1966). Following penetration of the root epidermis, S. cepivorum invades cortical parenchyma both intra‐ and intercellularly causing extensive tissue degradation (Abd‐El‐Razik et al ., 1973). S. cepivorum produces the phytotoxin oxalic acid (Stone & Armentrout, 1985) and pectin‐degrading isoenzymes of polygalacturonase (PG) and pectinesterase (PE), which diffuse several millimetres ahead of infection hyphae, and are associated with extensive disintegration of the cortical tissues.…”

Section: Introductionmentioning

confidence: 99%

The process of antagonism of Sclerotium cepivorum in white rot affected onion roots by Trichoderma koningii

Metcalf

Wilson

2001

Plant Pathology

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Trichoderma koningii (strain Tr5) grew in the epidermal mucilage of onion roots without entering healthy epidermal tissue. When placed on the epidermis of Sclerotium cepivorum‐infected roots, T. koningii colonized epidermal passage cells, with little colonization of other epidermal tissues, then branched and spread throughout the root cortical tissues damaged by enzymes and toxins which diffused ahead of S. cepivorum hyphae, and impeded the path of the infection. When T. koningii colonized infected tissue, many S. cepivorum hyphae became detached at septa, cell walls dissolved and many hyphal apices burst. Contact between hyphae was not necessary for lysis to occur. T. koningii produced two endochitinases (Rf 0·15 and 0·24) and two exo‐acting chitinolytic enzymes (Rf 0·46 and 0·62) during degradation of crabshell chitin and S. cepivorum cell walls. The Rf 0·24 and 0·46 proteins were detected when T. koningii colonized S. cepivorum‐infected roots and are likely to be a component of the antagonism process.

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Section: Introductionmentioning

confidence: 99%

The process of antagonism of Sclerotium cepivorum in white rot affected onion roots by Trichoderma koningii

Metcalf

Wilson

2001

Plant Pathology

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“…Sclerotium cepivorum sclerotia can survive in soil for more than 20 years ( Coley‐Smith et al ., 1990 ) and produce mycelium in response to the presence of Allium root exudates ( Coley‐Smith & Holt, 1966). The process of fungal penetration has been described ( Abd El‐Razik et al ., 1973 ; Stewart et al ., 1989a , b). Following penetration of the root epidermis, S. cepivorum invades cortical parenchyma both intra‐ and intercellularly, causing extensive tissue degradation ( Abd‐El‐Razik et al ., 1973 ).…”

Section: Introductionmentioning

confidence: 99%

“…The process of fungal penetration has been described ( Abd El‐Razik et al ., 1973 ; Stewart et al ., 1989a , b). Following penetration of the root epidermis, S. cepivorum invades cortical parenchyma both intra‐ and intercellularly, causing extensive tissue degradation ( Abd‐El‐Razik et al ., 1973 ). Destruction of epidermal cell walls beneath the stem base cuticle occurs two to three cells ahead of infection hyphae ( Stewart et al ., 1989b ).…”

Section: Introductionmentioning

confidence: 99%

Histology of Sclerotium cepivorum infection of onion roots and the spatial relationships of pectinases in the infection process

Metcalf¹,

Wilson

1999

Plant Pathology

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Sclerotium cepivorum (isolate Sc4) hyphae penetrated the epidermis and hypodermis of onion roots and grew into the cortex. Immediately following penetration only the cells through which S. cepivorum grew were lysed, but subsequently cells were killed and cell walls disintegrated ahead of the infection hyphae. Sclerotium cepivorum produced two polygalacturonases (PG) and two pectinesterases (PE) in culture. These isozymes were also found in infected onion root tissues and another PG and a PE were occasionally detected. Two isozymes of PG and three isozymes of PE diffused ahead of the infection hyphae. The spatial distribution of these enzymes was associated with cell death and cell wall degradation. The epidermis, hypodermis, endodermis and vascular tissues were more resistant to hydrolysis than the cortex, but only the endodermis and cells within it retained nuclei following hydrolysis of the surrounding cortical tissues. The cavity within the root cortex became ®lled with swollen, vacuolate S. cepivorum hyphae.

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“…White rot, caused by Sclerotium cepivorum, is a serious and economically important disease of onions (Allium cepa) in most onion-growing areas of the world, including Egypt (Abd El-Razik et al 1973;Schwartz and Mohan 1995;El-Sheshtawi et al 2009). The disease causes considerable reduction of the onion yield to uneconomic levels in a short period of time (ColeySmith et al 1987).…”

Section: Introductionmentioning

confidence: 99%

Efficiency assessment of the antifungal metabolites from Sclerotium cepivorum against onion white rot disease

et al. 2015

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The inhibitory effects of secondary metabolites of Sclerotium cepivorum against itself were studied both in vitro and in vivo. The highest inhibition of fungal growth and a 98.6 % reduction in the number of sclerotia was obtained with 50 % culture filtrate. No sclerotial germination was observed on media amended with culture filtrates at 10, 25 and 50 %. Methanol extract of mycelia and sclerotia, and ethyl acetate extract of culture filtrate both exhibited over 90 % inhibition of S. cepivorum growth at 1200 ppm. A chloroform extract of culture filtrate resulted in 71.1 % inhibition at 1200 ppm. All extracts completely suppressed the formation and germination of sclerotia at 400, 800 and 1200 ppm. In greenhouse experiments, no disease was observed with the ethyl acetate extract when onion seedlings were dipped in the extract for 4 or 8 h. The GC-MS analysis revealed 28 compounds in the methanol extract. The methanol extract contained mainly hexadecanoic acid methyl ester (31.16 %), whereas 5-hydroxymethylfurfural, HMF, (36.40 %) was the main constituent of the ethyl acetate extract. These results suggest that the secondary metabolites of S. cepivorum are potential and promising antifungal agents for the control of onion white rot. These results can be also applied to reduce the incidence and severity of other diseases in different crops.

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Studies on the Infection of Onion Plants by Sclerotium cepivorum Berk.

Cited by 27 publications

References 7 publications

The process of antagonism of Sclerotium cepivorum in white rot affected onion roots by Trichoderma koningii

The process of antagonism of Sclerotium cepivorum in white rot affected onion roots by Trichoderma koningii

Histology of Sclerotium cepivorum infection of onion roots and the spatial relationships of pectinases in the infection process

Efficiency assessment of the antifungal metabolites from Sclerotium cepivorum against onion white rot disease

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