scholarly journals Production of Cell Wall Degrading Enzymes and Toxins by Colletotrichum Capsici and Alternaria Alternata Causing Fruit ROT of Chillies

2008 ◽  
Vol 48 (4) ◽  
pp. 437-451 ◽  
Author(s):  
Theerthagiri Anand ◽  
Ramanujam Bhaskaran ◽  
Thiruvengadam Gandhi Karthikeyan ◽  
Manikam Rajesh ◽  
Govindasamy Senthilraja
Keyword(s):  
Cell Wall ◽  
Seed Germination ◽  
Alternaria Alternata ◽  
Fruit Rot ◽  
Cellulolytic Enzymes ◽  
Cell Wall Degrading Enzymes ◽  
Colletotrichum Capsici ◽  
Degrading Enzymes ◽  
Pectinolytic Enzymes

Production of Cell Wall Degrading Enzymes and Toxins byColletotrichum CapsiciandAlternaria AlternataCausing Fruit ROT of ChilliesThe virulent isolates ofColletotrichum capsiciandAlternaria alternataproduced more cellulolytic enzymesviz., C1and Cxin vitrothan the avirulent ones and the activity of these enzymes increased with the increase in age of culture. The virulent isolates ofC. capsiciandA. alternataproduced more pectinolytic enzymes (macerating enzymes, pectin methyl esterase and endo polygalacturonase) than the avirulent ones. All the pectinolytic enzymes were highly active in 10-day-old culture and the activities decreased with the increase of culture age. Whereas the activity of enzymes produced by avirulent isolate of pathogens did not decrease and these enzyme activities increased with the increase in the age of culture. These pathogens also produced nonspecific toxic metabolites in culture filtrate which reduced seed germination, root length, shoot length and vigour index of the seedlings of chilli, rice, mungbean, maize, cotton, groundnut, okra, egg plant, cucumber and tomato. The toxins of the pathogens reduced seed germination and caused mortality of chilli seedlings in pot culture. The toxins also produced phytotoxic symptoms in the treated ripe and green chilli fruits and leaves.

scholarly journals Pyramiding Unmarked Deletions in Ralstonia solanacearum Shows That Secreted Proteins in Addition to Plant Cell-Wall-Degrading Enzymes Contribute to Virulence

2005 ◽  
Vol 18 (12) ◽  
pp. 1296-1305 ◽  
Author(s):  
Huanli Liu ◽  
Shuping Zhang ◽  
Mark A. Schell ◽  
Timothy P. Denny
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Ralstonia Solanacearum ◽  
Plant Cell Wall ◽  
Secreted Proteins ◽  
Cellulolytic Enzymes ◽  
Wild Type ◽  
Cell Wall Degrading Enzymes ◽  
Tomato Plants ◽  
Degrading Enzymes

Ralstonia solanacearum, like many phytopathogenic bacteria, makes multiple extracellular plant cell-wall-degrading enzymes (CWDE), some of which contribute to its ability to cause wilt disease. CWDE and many other proteins are secreted to the milieu via the highly conserved type II protein secretion system (T2SS). R. solanacearum with a defective T2SS is weakly virulent, but it is not known whether this is due to absence of all the CWDE or the loss of other secreted proteins that contribute to disease. These alternatives were investigated by creating mutants of wild-type strain GMI1000 lacking either the T2SS or up to six CWDE and comparing them for virulence on tomato plants. To create unmarked deletions, genomic regions flanking the target gene were polymerase chain reaction (PCR)-amplified, were fused using splice overlap extension PCR, were cloned into a suicide plasmid harboring the sacB counter-selectable marker, and then, were site-specifically introduced into the genome. Various combinations of five deletions (δpehA, δpehB, δpehC, δpme, and δegl) and one inactivated allele (cbhA::aphA-3) resulted in 15 mutants missing one to six CWDE. In soil-drench inoculation assays, virulence of mutants lacking only pectic enzymes (PehA, PehB, PehC, and Pme) was not statistically different from GMI1000, but all the mutants lacking one or both cellulolytic enzymes (Egl or CbhA) wilted plants significantly more slowly than did the wild type. The GMI-6 mutant that lacks all six CWDE was more virulent than the mutant lacking only its two cellulolytic enzymes, and both were significantly more virulent than the T2SS mutant (GMI-D). Very similar results were observed in wounded-petiole inoculation assays, so GMI-6 and GMI-D appear to be less capable of colonizing tomato tissues after invasion. Because the T2SS mutant was much less virulent than the sixfold CWDE mutant, we conclude that other secreted proteins contribute substantially to the ability of R. solanacearum GMI1000 to systemically colonize tomato plants.

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.

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