Characterization of the watermelon seedling infection process byFusarium oxysporumf. sp.niveum

2015 ◽  
Vol 64 (5) ◽  
pp. 1076-1084 ◽  
Author(s):  
M. Zhang ◽  
J. H. Xu ◽  
G. Liu ◽  
X. F. Yao ◽  
P. F. Li ◽  
...  
Keyword(s):  
Infection Process ◽  
Seedling Infection

scholarly journals Biofilm Formation in Xanthomonas arboricola pv. pruni: Structure and Development

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 546
Author(s):  
Pilar Sabuquillo ◽  
Jaime Cubero
Keyword(s):  
Biofilm Formation ◽  
Extracellular Polymeric Substances ◽  
Environmental Changes ◽  
Nutrient Content ◽  
Infection Process ◽  
Bacterial Attachment ◽  
Key Factors ◽  
Cell Structures ◽  
Microscopy Techniques

Xanthomonasarboricola pv. pruni (Xap) causes bacterial spot of stone fruit and almond, an important plant disease with a high economic impact. Biofilm formation is one of the mechanisms that microbial communities use to adapt to environmental changes and to survive and colonize plants. Herein, biofilm formation by Xap was analyzed on abiotic and biotic surfaces using different microscopy techniques which allowed characterization of the different biofilm stages compared to the planktonic condition. All Xap strains assayed were able to form real biofilms creating organized structures comprised by viable cells. Xap in biofilms differentiated from free-living bacteria forming complex matrix-encased multicellular structures which become surrounded by a network of extracellular polymeric substances (EPS). Moreover, nutrient content of the environment and bacterial growth have been shown as key factors for biofilm formation and its development. Besides, this is the first work where different cell structures involved in bacterial attachment and aggregation have been identified during Xap biofilm progression. Our findings provide insights regarding different aspects of the biofilm formation of Xap which improve our understanding of the bacterial infection process occurred in Prunus spp and that may help in future disease control approaches.

scholarly journals Selection of Unusual Actinomycetal Primary σ70 Factors by Plant-Colonizing Frankia Strains

2004 ◽  
Vol 70 (2) ◽  
pp. 991-998 ◽  
Author(s):  
Céline Lavire ◽  
Didier Blaha ◽  
Benoit Cournoyer
Keyword(s):  
Growth Conditions ◽  
Infection Process ◽  
The Other ◽  
Gene Library ◽  
Pcr Screening ◽  
Liquid Cultures ◽  
Total Dna ◽  
Root Hair Infection ◽  
Selection Of

ABSTRACT Functional adaptations of σ70 transcriptional factors led to the emergence of several paralogous lineages, each one being specialized for gene transcription under particular growth conditions. Screening of a Frankia strain EaI-12 gene library by σ70 DNA probing allowed the detection and characterization of a novel actinomycetal primary (housekeeping) σ70 factor. Phylogenetic analysis positioned this factor in the RpoD cluster of proteobacterial and low-G+C-content gram-positive factors, a cluster previously free of any actinobacterial sequences. σ70 DNA probing of Frankia total DNA blots and PCR screening detected one or two rpoD-like DNA regions per species. rpoD matched the conserved region in all of the species tested. The other region was found to contain sigA, an alternative primary factor. sigA appeared to be strictly distributed among Frankia species infecting plants by the root hair infection process. Both genes were transcribed by Frankia strain ACN14a grown in liquid cultures. The molecular phylogeny of the σ70 family determined with Frankia sequences showed that the alternative actinomycetal factors and the essential ones belonged to the same radiation. At least seven distinct paralogous lineages were observed among this radiation, and gene transfers were detected in the HrdB actinomycetal lineage.

Purification and characterization of a constitutive polygalacturonase associated with the infection process of French bean leaves by Botrytis cinerea

1990 ◽  
Vol 68 (9) ◽  
pp. 1921-1930 ◽  
Author(s):  
G. Leone ◽  
E. A. M. Schoffelmeer ◽  
J. Van den Heuvel
Keyword(s):  
Botrytis Cinerea ◽  
Reaction Rate ◽  
French Bean ◽  
Infection Process ◽  
Purification Procedure ◽  
Purification And Characterization ◽  
Titration Curves ◽  
Optimal Ph ◽  
Bean Leaves

The constitutively produced polygalacturonase isoenzyme PG2 was isolated from culture filtrates of Botrytis cinerea, purified to homogeneity, and characterized. The shape of titration curves of PG2 and two other polygalacturonase isoenzymes explained the difficulties found in separating superimposed pectic enzyme activities during the purification procedure. PG2 hydrolyzed sodium polygalacturonate more quickly than pectin. The optimal pH for PG2 activity with polygalacturonate was 4.5 and with pectin, 4.0. PG2 activity was also influenced by the presence of NaCl or CaCl2 in the reaction mixture. Analysis of the breakdown products by paper chromatography and a comparison of the reaction rate by viscosimetry and reducing group assay revealed that PG2 has an endocatalytic mode of action on polygalacturonate. The isoelectric point and the molecular mass of PG2 were estimated to be 9.1 and 23.0 kDa, respectively. Key words: Botrytis cinerea, chromatofocusing, endopolygalacturonase, purification, substrate specificity, titration curve.

scholarly journals Characterization of the infection process by Peronospora belbahrii on basil by scanning electron microscopy

Heliyon ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. e01117 ◽  
Author(s):  
Guirong Zhang ◽  
Arthur Thompson ◽  
David Schisler ◽  
Eric T. Johnson
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Infection Process ◽  
Scanning Electron

scholarly journals Molecular Characterization of the NADPH Oxidase Complex in the Ergot Fungus Claviceps purpurea: CpNox2 and CpPls1 Are Important for a Balanced Host-Pathogen Interaction

2013 ◽  
Vol 26 (10) ◽  
pp. 1151-1164 ◽  
Author(s):  
Janine Schürmann ◽  
Dagmar Buttermann ◽  
Andrea Herrmann ◽  
Sabine Giesbert ◽  
Paul Tudzynski
Keyword(s):  
Nadph Oxidase ◽  
Pathogenic Fungi ◽  
Infection Process ◽  
Regulatory Subunit ◽  
Claviceps Purpurea ◽  
Oxygen Species ◽  
Disease Symptoms ◽  
Host Pathogen Interaction ◽  
Nadph Oxidase Complex

Reactive oxygen species producing NADPH oxidase (Nox) complexes are involved in defense reactions in animals and plants while they trigger infection-related processes in pathogenic fungi. Knowledge about the composition and localization of these complexes in fungi is limited; potential components identified thus far include two to three catalytical subunits, a regulatory subunit (NoxR), the GTPase Rac, the scaffold protein Bem1, and a tetraspanin-like membrane protein (Pls1). We showed that, in the biotrophic grass-pathogen Claviceps purpurea, the catalytical subunit CpNox1 is important for infection. Here, we present identification of major Nox complex partners and a functional analysis of CpNox2 and the tetraspanin CpPls1. We show that, as in other fungi, Nox complexes are important for formation of sclerotia; CpRac is, indeed, a complex partner because it interacts with CpNoxR, and CpNox1/2 and CpPls1 are associated with the endoplasmatic reticulum. However, unlike in all other fungi, Δcppls1 is more similar to Δcpnox1 than to Δcpnox2, and CpNox2 is not essential for infection. In contrast, Δcpnox2 shows even more pronounced disease symptoms, indicating that Cpnox2 controls the infection process and moderates damage to the host. These data confirm that fungal Nox complexes have acquired specific functions dependent of the lifestyle of the pathogen.

Morphological and Enzymatical Characterization of the Infection Process ofPythium ultimuminDendrobium officinale(Orchidaceae)

2015 ◽  
Vol 36 (3) ◽  
pp. 275-286 ◽  
Author(s):  
Yong-Mei Xing ◽  
Xiang-Dong Li ◽  
Meng-Meng Liu ◽  
Gang Zhang ◽  
Chun-Lan Wang ◽  
...  
Keyword(s):  
Infection Process

Characterization of an extracellular protease and its cDNA from the nematode-trapping fungus Monacrosporium microscaphoides

2006 ◽  
Vol 52 (2) ◽  
pp. 130-139 ◽  
Author(s):  
Miao Wang ◽  
Jinkui Yang ◽  
Ke-Qin Zhang
Keyword(s):  
Serine Protease ◽  
Catalytic Triad ◽  
Infection Process ◽  
Gene Encoding ◽  
Protein Substrates ◽  
Nematocidal Activity ◽  
Infection Mechanisms ◽  
Biocontrol Potential

To better exploit the biocontrol potential of nematophagous fungi, it is important to fully understand the molecular background of the infection process. In this paper, several nematode-trapping fungi were surveyed for nematocidal activity. From the culture filtrate of Monacrosporium microscaphoides, a neutral serine protease (designated Mlx) was purified by chromatography. This protease could immobilize the nematode Penagrellus redivivus in vitro and degrade its purified cuticle, suggesting that Mlx could serve as a virulence factor during infection. Characterization of the purified protease revealed a molecular mass of approximately 39 kDa, an isoelectric point of 6.8, and optimum activity at pH 9 at 65 °C. Mlx has broad substrate specificity, and it hydrolyzes protein substrates, including casein, skimmed milk, collagen, and bovine serum albumin. The gene encoding Mlx was also cloned and the nucleotide sequence was determined. The deduced amino acid sequence contained the conserved catalytic triad of aspartic acid – histidine – serine and showed high similarity with two cuticle-degrading proteases (PII and Aoz1), which were purified from the nematode-trapping fungus Arthrobotrys oligospora. Research on infection mechanisms of nematode-trapping fungi has thus far only focused on A. oligospora. However, little is known about other nematode-trapping fungi. Our report is among the first to describe the purification and cloning of an infectious protease from a different nematode-trapping fungus.Key words: extracellular serine protease, Monacrosporium microscaphoides, nematode-trapping fungus, nematocidal activity.

scholarly journals Host-Elicited Germination and Mechanism of Penetration in Broomrape (Orobanche Spp.)

1993 ◽  
Author(s):  
Daniel M. Joel ◽  
John C. Steffens ◽  
Alfred M. Mayer
Keyword(s):  
Host Cell ◽  
Sesquiterpene Lactone ◽  
Cell Walls ◽  
High Field ◽  
Infection Process ◽  
Pectin Methyl Esterase ◽  
Parasitic Weed ◽  
Enzymatic Nature

Orobanche is an important parasitic weed. For developing novel methods for its control, a thorough understanding of crucial stages of its development is needed. Therefore, the objectives of this project were characterization of Orobanche germination stimulants, analysis of mechanisms of haustorial penetration, and characterization and isolation of penetration enzymes. The first highly potent natural germination stimulant for Orobanche was isolated from sunflower and identified by high-field 1D (1H and 13C), 2D (1H-1H COSY, HMQC, HMBC)-NMR, GC.FT-IR, and GC.MS as costuslactone, a guaiane type sesquiterpene lactone that resembles strigol only in possessing a lactone moiety that is required for activity. The first direct in situ evidence for the enzymatic nature of the infection process of a parasitic angiosperm was established. Pectin deesterification and depletion of pectins in host cell walls were shown adjacent to haustorial cells. Pectin methyl esterase and polygalacturonase were immunocytochemically detected in intrusive cells and in adjacent host apoplast. Orobanche tissues contain inhibitors of PGase activity. PME and three PGases were isolated from Orobanche calli. PME was characterized and purified, and antibodies were prepared against it. This study presents novel findings regarding parasitism in Orobanche, which may help to open up new approaches for controlling broomrapes.

scholarly journals A Hypersensitivity-Like Response to Meloidogyne graminicola in Rice (Oryza sativa)

2018 ◽  
Vol 108 (4) ◽  
pp. 521-528 ◽  
Author(s):  
Ngan Thi Phan ◽  
Dirk De Waele ◽  
Mathias Lorieux ◽  
Lizhong Xiong ◽  
Stephane Bellafiore
Keyword(s):  
Resistance Genes ◽  
Defense Mechanism ◽  
Hybrid Sterility ◽  
Infection Process ◽  
Oryza Glaberrima ◽  
Sources Of Resistance ◽  
Major Step ◽  
Root Cells ◽  
Meloidogyne Graminicola

Meloidogyne graminicola is a major plant-parasitic nematode affecting rice cultivation in Asia. Resistance to this nematode was found in the African rice genotypes Oryza glaberrima and O. longistaminata; however, due to interspecific hybrid sterility, the introgression of resistance genes in the widely consumed O. sativa varieties remains challenging. Recently, resistance was found in O. sativa and, here, we report for the first time the histological and genetic characterization of the resistance to M. graminicola in Zhonghua 11, an O. sativa variety. Bright-light microscopy and fluorescence observations of the root tissue of this variety revealed that the root cells surrounding the nematode displayed a hypersensitivity-like reaction with necrotic cells at early stages of infection when nematodes are migrating in the root’s mesoderm. An accumulation of presumably phenolic compounds in the nematodes’ neighboring root cells was also observed. In addition, at a later stage of infection, not only were few feeding sites observed but also the giant cells were underdeveloped, underlining an incompatible interaction. Furthermore, we generated a hybrid O. sativa population by crossing Zhonghua 11 with the susceptible O. sativa variety IR64 in order to describe the genetic background of this resistance. Our data suggested that the resistance to M. graminicola infection was qualitative rather than quantitative and, therefore, major resistance genes must be involved in this infection process. The full characterization of the defense mechanism and the preliminary study of the genetic inheritance of novel sources of resistance to Meloidogyne spp. in rice constitute a major step toward their use in crop breeding.

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