Rhizosphere-competent isolates of streptomycete and non-streptomycete actinomycetes capable of producing cell-wall-degrading enzymes to controlPythium aphanidermatumdamping-off disease of cucumber

2006 ◽  
Vol 84 (2) ◽  
pp. 211-222 ◽  
Author(s):  
Khaled A. El-Tarabily
Keyword(s):  
Cell Wall ◽  
Rhizosphere Soil ◽  
Damping Off ◽  
Cell Wall Degrading Enzymes ◽  
Cucumis Sativus L ◽  
Degrading Enzymes ◽  
Rhizosphere Competence ◽  
Volatile Inhibitors ◽  
Micromonospora Chalcea

Fifty-eight streptomycete and 35 non-streptomycete actinomycetes were isolated from cucumber rhizosphere soil. These isolates were screened for the production of cell-wall-degrading enzymes using mycelial ( Pythium aphanidermatum (Edson) Fitzp.) fragment agar. Eighteen promising isolates were screened for their competence as root colonizers. Eight isolates showing exceptional rhizosphere competence significantly inhibited, in vitro, P. aphanidermatum, the causal agent of postemergence damping-off of cucumber ( Cucumis sativus L.) seedlings. The four most inhibitory isolates ( Actinoplanes philippinensis Couch, Microbispora rosea Nonomura and Ohara, Micromonospora chalcea (Foulerton) Ørskov, and Streptomyces griseoloalbus (Kudrina) Pridham et al.) produced in vitro β-1,3-, β-1,4-, and β-1,6-glucanases and caused lysis of P. aphanidermatum hyphae. None of these produced volatile inhibitors or siderophores. Only S. griseoloalbus produced diffusible inhibitory metabolites, whilst A. philippinensis and Micromonospora chalcea parasitized the oospores of P. aphanidermatum. These four isolates were subsequently tested in the greenhouse, individually or as a mixture, for their ability to suppress damping-off of cucumber seedlings in soil with or without cellulose amendment. The treatment, which included all four isolates in soil amended with cellulose, was significantly superior to all other treatments in suppressing damping-off and was nearly as good as the metalaxyl treatment. Results show that there is a potential to use a mixture of antagonistic rhizosphere-competent actinomycetes along with cellulose amendment rather than fungicides for the field management of this disease. This is the first study that has involved the screening of rhizosphere-competent non-streptomycete actinomycetes capable of producing cell-wall-degrading enzymes, for the management of Pythium diseases.

scholarly journals Digestibility of grass silage.

1990 ◽  
Vol 38 (3B) ◽  
pp. 407-422
Author(s):  
A. Steg ◽  
S.F. Spoelstra ◽  
J.M. van der Meer ◽  
V.A. Hindle
Keyword(s):  
Cell Wall ◽  
Rumen Fluid ◽  
Cell Wall Degrading Enzymes ◽  
Grass Silage ◽  
Degrading Enzymes

A total of 50 grass silages were tested in digestibility trials using Texel wethers. The feed silages were wilted of varying DM contents and treated with cell-wall degrading enzymes. The accuracy of feed evaluation was studied using laboratory analyses, including cell-wall analyses, incubation in vitro with rumen fluid and the enzymic procedure. A comparison was made between these results and the current and recently suggested procedures for prediction of digestibility of grass silage. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Characterization of Cell Wall Degrading Enzymes of Rhizoctonia solani AG-3 from Tobacco Target Spot

2014 ◽  
Vol 1010-1012 ◽  
pp. 1161-1164
Author(s):  
Yan Qin Zhao ◽  
Yuan Hua Wu ◽  
Xiu Xiang Zhao ◽  
Meng Nan An ◽  
Jian Guang Chen ◽  
...  
Keyword(s):  
Cell Wall ◽  
Rhizoctonia Solani ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes ◽  
Yield And Quality ◽  
Target Spot ◽  
Causal Pathogen

Rhizoctonia solaniKühn is a causal pathogen responsible for many types of plant disease worldwide and a major soilborne fungal pathogen that severely impairs yield and quality of tobacco worldwide. Activities, pathogenicity of the cell wall-degrading enzymes produced by theRhizoctoniasolanifrom tobacco target spot disease both in liquid medium and in tobacco tissue were studied. The result showed thatR.solanifrom tobacco can produce pectinase and cellulase both in vitro and vivo, and the activity of PG and PMG was the highest in vitro. The activity of Cx and β-glucosidase was the highest in vivo, and enzyme production ability of strong pathogenicity strains is stronger than the weak pathogenicity strains in vitro.

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 role of L-arabinose metabolism for Escherichia coli O157:H7 in edible plants

2021 ◽  
Author(s):  
Louise Emma Crozier ◽  
Jacqueline Marshall ◽  
Ashleigh Holmes ◽  
Kathryn Wright ◽  
Yannick Rossez ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Escherichia Coli O157 ◽  
In Planta ◽  
Cell Wall Degrading Enzymes ◽  
Cell Wall Polysaccharides ◽  
E Coli ◽  
Degrading Enzymes ◽  
Food Borne

Arabinose is a major plant aldopentose in the form of arabinans complexed in cell wall polysaccharides or glycoproteins (AGP), but comparatively rare as a monosaccharide. L-arabinose is an important bacterial metabolite, accessed by pectolytic microorganisms such as Pectobacterium atrosepticum via pectin and hemicellulose degrading enzymes. However, not all plant-associated microbes encode cell wall degrading enzymes, yet can metabolise L-arabinose, raising questions about their use of and access to the glycan in plants. Therefore, we examined L-arabinose metabolism in the food-borne pathogen Escherichia coli O157:H7 (isolate Sakai) during its colonisation of plants. L-arabinose metabolism (araBA) and transport (araF) genes were activated at 18 C in vitro by L-arabinose and expressed over prolonged periods in planta. Although deletion of araBAD did not impact the colonisation ability of E. coli O157:H7 (Sakai) on plants, araA was induced on exposure to spinach cell wall polysaccharides. Furthermore, debranched and arabinan oligosaccharides induced ara metabolism gene expression in vitro, and stimulated modest proliferation, while immobilised pectin did not. Thus, E. coli O157:H7 (Sakai) can utilise pectin/AGP-derived L-arabinose as a metabolite, but differs fundamentally in ara gene organisation, transport and regulation from the related pectinolytic species P. atrosepticum, reflective of distinct plant-associated lifestyles.

scholarly journals Computational proteomics analysis reveals pathogen secreted carbohydrate active enzymes in tomato xylem sap

2021 ◽  
Author(s):  
Abhijeet Roy ◽  
Barsha Kalita ◽  
Aiswarya Jayaprakash ◽  
Annamalai Arunachalam ◽  
Lakshmi PTV
Keyword(s):  
Cell Wall ◽  
Tomato Plant ◽  
Xylem Sap ◽  
In Planta ◽  
Cell Wall Degrading Enzymes ◽  
Carbohydrate Active Enzymes ◽  
Causal Organism ◽  
Degrading Enzymes ◽  
Susceptible Tomato

Abstract Fusarium oxysporum f. sp. lycopersici (Fol), a causal organism of Fusarium wilt in the tomato plant, secretes cell wall degrading enzymes, also known as carbohydrate-active enzymes (CAZymes). These are crucial during colonization and pathogenesis, as evidenced by several proteomic studies, revealing the importance of these CAZymes in virulence and pathogenicity. However, few of them have been done in-planta, exhibiting differences in the expression of these cell wall degrading enzymes compared to in-vitro studies. Therefore, to explore the CAZymes involved in pathogenesis while residing in the host plant, an in-planta (xylem sap) proteomics of a susceptible tomato variety affected with Fol was done. Most of these CAZymes belonged to the hydrolase and oxidoreductase families having no significant homology with tomato proteins. Nearly 90% of them were predicted to be soluble and extracellular. The core CAZymes families with interactional evidence identified were AA3, GH3, GH18, GH20, GH28, GH43, GH47, GH55 and CE8. Thus, apart from annotating some of the hypothetical proteins to be CAZymes, the study sheds light on CAZymes families that may have a role in the pathogenesis and survival of this fungus in the susceptible tomato plant.

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