scholarly journals Loss of bcbrn1 and bcpks13 in Botrytis cinerea Not Only Blocks Melanization But Also Increases Vegetative Growth and Virulence

2015 ◽  
Vol 28 (10) ◽  
pp. 1091-1101 ◽  
Author(s):  
Chenghua Zhang ◽  
Yifan He ◽  
Pinkuan Zhu ◽  
Lu Chen ◽  
Yiwen Wang ◽  
...  
Keyword(s):  
Cell Wall ◽  
Botrytis Cinerea ◽  
Plant Cell Wall ◽  
Hydrolytic Enzyme ◽  
Complete Medium ◽  
Cell Wall Degrading Enzymes ◽  
Mycelium Growth ◽  
Necrotrophic Pathogen ◽  
Melanin Biosynthesis

Botrytis cinerea is a necrotrophic pathogen that causes gray mold disease in a broad range of plants. Dihydroxynaphthalene (DHN) melanin is a major component of the extracellular matrix of B. cinerea, but knowledge of the exact role of melanin biosynthesis in this pathogen is unclear. In this study, we characterize two genes in B. cinerea, bcpks13 and bcbrn1, encoding polyketide synthase and tetrahydroxynaphthalene (THN) reductases, respectively, and both have predicted roles in DHN melanin biosynthesis. The ∆bcpks13 and ∆bcbrn1 mutants show white and orange pigmentation, respectively, and the mutants are also deficient in conidiation in vitro but show enhanced growth rates and virulence on hosts. Moreover, the mutants display elevated acidification of the complete medium (CM), probably due to oxalic acid secretion and secretion of cell wall–degrading enzymes, and preferably utilize plant cell-wall components as carbon sources for mycelium growth in vitro. In contrast, overexpression of bcbrn1 (OE::bcbrn1 strain) results in attenuated hydrolytic enzyme secretion, acidification ability, and virulence. Taken together, these results indicate that bcpks13 and bcbrn1 participate in diverse cellular and developmental processes, such as melanization and conidiation in B. cinerea in vitro, but they negatively regulate the virulence of this pathogen.

scholarly journals The Endo-Arabinanase BcAra1 Is a Novel Host-Specific Virulence Factor of the Necrotic Fungal Phytopathogen Botrytis cinerea

2014 ◽  
Vol 27 (8) ◽  
pp. 781-792 ◽  
Author(s):  
Majse Nafisi ◽  
Maria Stranne ◽  
Lisha Zhang ◽  
Jan A. L. van Kan ◽  
Yumiko Sakuragi
Keyword(s):  
Cell Wall ◽  
Botrytis Cinerea ◽  
Plant Cell ◽  
Plant Pathogens ◽  
Plant Cell Wall ◽  
High Efficiency ◽  
Microbial Infection ◽  
Cell Wall Degrading Enzymes ◽  
Novel Host

The plant cell wall is one of the first physical interfaces encountered by plant pathogens and consists of polysaccharides, of which arabinan is an important constituent. During infection, the necrotrophic plant pathogen Botrytis cinerea secretes a cocktail of plant cell-wall-degrading enzymes, including endo-arabinanase activity, which carries out the breakdown of arabinan. The roles of arabinan and endo-arabinanases during microbial infection were thus far elusive. In this study, the gene Bcara1 encoding for a novel α-1,5-L-endo-arabinanase was identified and the heterologously expressed BcAra1 protein was shown to hydrolyze linear arabinan with high efficiency whereas little or no activity was observed against the other oligo- and polysaccharides tested. The Bcara1 knockout mutants displayed reduced arabinanase activity in vitro and severe retardation in secondary lesion formation during infection of Arabidopsis leaves. These results indicate that BcAra1 is a novel endo-arabinanase and plays an important role during the infection of Arabidopsis. Interestingly, the level of Bcara1 transcript was considerably lower during the infection of Nicotiana benthamiana compared with Arabidopsis and, consequently, the ΔBcara1 mutants showed the wild-type level of virulence on N. benthamiana leaves. These results support the conclusion that the expression of Bcara1 is host dependent and is a key determinant of the disease outcome.

scholarly journals Induction of Fusarium lytic Enzymes by Extracts from Resistant and Susceptible Cultivars of Pea (Pisum sativum L.)

Pathogens ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 976
Author(s):  
Lakshmipriya Perincherry ◽  
Chaima Ajmi ◽  
Souheib Oueslati ◽  
Agnieszka Waśkiewicz ◽  
Łukasz Stępień
Keyword(s):  
Cell Wall ◽  
Plant Extracts ◽  
Plant Cell Wall ◽  
Pathogenic Fungi ◽  
Human Beings ◽  
Cell Wall Degrading Enzymes ◽  
Lytic Enzymes ◽  
Mycelium Growth ◽  
Oat Bran

Being pathogenic fungi, Fusarium produce various extracellular cell wall-degrading enzymes (CWDEs) that degrade the polysaccharides in the plant cell wall. They also produce mycotoxins that contaminate grains, thereby posing a serious threat to animals and human beings. Exposure to mycotoxins occurs through ingestion of contaminated grains, inhalation and through skin absorption, thereby causing mycotoxicoses. The toxins weaken the host plant, allowing the pathogen to invade successfully, with the efficiency varying from strain to strain and depending on the plant infected. Fusariumoxysporum predominantly produces moniliformin and cyclodepsipeptides, whereas F. proliferatum produces fumonisins. The aim of the study was to understand the role of various substrates and pea plant extracts in inducing the production of CWDEs and mycotoxins. Additionally, to monitor the differences in their levels when susceptible and resistant pea plant extracts were supplemented. The cultures of F. proliferatum and F. oxysporum strains were supplemented with various potential inducers of CWDEs. During the initial days after the addition of substrates, the fungus cocultivated with pea extracts and other carbon substrates showed increased activities of β-glucosidase, xylanase, exo-1,4-glucanase and lipase. The highest inhibition of mycelium growth (57%) was found in the cultures of F. proliferatum strain PEA1 upon the addition of cv. Sokolik extract. The lowest fumonisin content was exhibited by the cultures with the pea extracts and oat bran added, and this can be related to the secondary metabolites and antioxidants present in these substrates.

scholarly journals The Xylanase Inhibitor TAXI-I Increases Plant Resistance to Botrytis cinerea by Inhibiting the BcXyn11a Xylanase Necrotizing Activity

Plants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 601
Author(s):  
Silvio Tundo ◽  
Maria Chiara Paccanaro ◽  
Ibrahim Elmaghraby ◽  
Ilaria Moscetti ◽  
Renato D’Ovidio ◽  
...  
Keyword(s):  
Cell Wall ◽  
Botrytis Cinerea ◽  
Plant Cell Wall ◽  
Wild Type ◽  
Cell Wall Degrading Enzymes ◽  
Targeted Deletion ◽  
Plant Infection ◽  
Transgenic Lines ◽  
Xylanase Inhibitor ◽  
Main Component

During host plant infection, pathogens produce a wide array of cell wall degrading enzymes (CWDEs) to break the plant cell wall. Among CWDEs, xylanases are key enzymes in the degradation of xylan, the main component of hemicellulose. Targeted deletion experiments support the direct involvement of the xylanase BcXyn11a in the pathogenesis of Botrytis cinerea. Since the Triticum aestivum xylanase inhibitor-I (TAXI-I) has been shown to inhibit BcXyn11a, we verified if TAXI-I could be exploited to counteract B. cinerea infections. With this aim, we first produced Nicotiana tabacum plants transiently expressing TAXI-I, observing increased resistance to B. cinerea. Subsequently, we transformed Arabidopsis thaliana to express TAXI-I constitutively, and we obtained three transgenic lines exhibiting a variable amount of TAXI-I. The line with the higher level of TAXI-I showed increased resistance to B. cinerea and the absence of necrotic lesions when infiltrated with BcXyn11a. Finally, in a droplet application experiment on wild-type Arabidopsis leaves, TAXI-I prevented the necrotizing activity of BcXyn11a. These results would confirm that the contribution of BcXyn11a to virulence is due to its necrotizing rather than enzymatic activity. In conclusion, our experiments highlight the ability of the TAXI-I xylanase inhibitor to counteract B. cinerea infection presumably by preventing the necrotizing activity of BcXyn11a.

scholarly journals The infection cushion: a fungal “weapon” of plant-biomass destruction

2020 ◽  
Author(s):  
Mathias Choquer ◽  
Christine Rascle ◽  
Isabelle R Gonçalves ◽  
Amélie de Vallée ◽  
Cécile Ribot ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell Wall ◽  
Plant Biomass ◽  
Ornamental Plants ◽  
Sugar Transport ◽  
Differential Staining ◽  
List Type ◽  
In Planta ◽  
Cell Wall Degrading Enzymes

SummaryGrey mold disease affects fruits, vegetables and ornamental plants around the world, causing considerable losses every year. Its causing agent, the necrotrophic fungus Botrytis cinerea, produces infection cushions (IC) that are compound appressorial structures dedicated to the penetration of the plant tissues.A microarray analysis was performed to identify genes up-regulated in mature IC. The expression data were supported by RT-qPCR analysis performed in vitro and in planta, proteomic analysis of the IC secretome and mutagenesis of two candidate genes.1,231 up-regulated genes and 79 up-accumulated proteins were identified. They highlight a secretion of ROS, secondary metabolites including phytotoxins, and proteins involved in virulence: proteases, plant cell wall degrading enzymes and necrosis inducers. The role in pathogenesis was confirmed for two up-regulated fasciclin genes. DHN-melanin pathway and chitin deacetylases genes are up-regulated and the conversion of chitin into chitosan was confirmed by differential staining of the IC cell wall. In addition, up-regulation of sugar transport and sugar catabolism encoding genes was found.These results support a role for the B. cinerea IC in plant penetration and suggest other unexpected roles for this fungal organ, in camouflage, necrotrophy or nutrition of the pathogen.

scholarly journals The dual function receptor kinase, OsWAKL21.2, is involved in elaboration of lipaseA/esterase induced immune responses in rice

2019 ◽  
Author(s):  
Kamal Kumar Malukani ◽  
Ashish Ranjan ◽  
Hota Shiva Jyothi ◽  
Hitendra Kumar Patel ◽  
Ramesh V. Sonti
Keyword(s):  
Cell Wall ◽  
Immune Responses ◽  
Plant Pathogens ◽  
Plant Cell Wall ◽  
Ectopic Expression ◽  
Dual Function ◽  
Receptor Kinase ◽  
Cell Wall Degrading Enzymes ◽  
Cell Wall Damage

AbstractPlant pathogens secrete cell wall degrading enzymes (CWDEs) to degrade various components of the plant cell wall. Plants sense this cell wall damage as a mark of infection and induce immune responses. Little is known about the plant functions that are involved in the elaboration of cell wall damage-induced immune responses. Transcriptome analysis revealed that a rice receptor kinase, WALL-ASSOCIATED KINASE-LIKE 21 (OsWAKL21.2), is upregulated following treatment with either Xanthomonas oryzae pv. oryzae (Xoo, a bacterial pathogen) or lipaseA/esterase (LipA: a CWDE of Xoo). Downregulation of OsWAKL21.2 attenuates LipA mediated immune responses. Overexpression of OsWAKL21.2 in rice mimics LipA treatment mediated induction of immune responses and enhanced expression of defence related genes, indicating it could be involved in the perception of LipA induced cell wall damage in rice. OsWAKL21.2 is a dual function kinase having in-vitro kinase and guanylate cyclase (GC) activities. Ectopic expression of OsWAKL21.2 in Arabidopsis also activates plant immune responses. Interestingly, OsWAKL21.2 needs kinase activity to activate rice immune responses while in Arabidopsis it needs GC activity. Our study reveals a novel receptor kinase involved in elaboration of cell wall damage induced rice immune responses that can activate similar immune responses in two different species via two different mechanisms.One sentence SummaryA novel rice receptor WAKL21 that sense cell wall damage caused by Xanthomonas secreted cell wall degrading enzyme to induce immune responses.

scholarly journals A specific fungal transcription factor controls effector gene expression and orchestrates the establishment of the necrotrophic pathogen lifestyle on wheat

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Darcy A. B. Jones ◽  
Evan John ◽  
Kasia Rybak ◽  
Huyen T. T. Phan ◽  
Karam B. Singh ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Wall ◽  
Transcription Factor ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Cell Wall Degradation ◽  
Necrotrophic Pathogen ◽  
Effector Gene ◽  
Plant Cell Wall Degradation

Abstract The fungus Parastagonospora nodorum infects wheat through the use of necrotrophic effector (NE) proteins that cause host-specific tissue necrosis. The Zn2Cys6 transcription factor PnPf2 positively regulates NE gene expression and is required for virulence on wheat. Little is known about other downstream targets of PnPf2. We compared the transcriptomes of the P. nodorum wildtype and a strain deleted in PnPf2 (pf2-69) during in vitro growth and host infection to further elucidate targets of PnPf2 signalling. Gene ontology enrichment analysis of the differentially expressed (DE) genes revealed that genes associated with plant cell wall degradation and proteolysis were enriched in down-regulated DE gene sets in pf2-69 compared to SN15. In contrast, genes associated with redox control, nutrient and ion transport were up-regulated in the mutant. Further analysis of the DE gene set revealed that PnPf2 positively regulates twelve genes that encode effector-like proteins. Two of these genes encode proteins with homology to previously characterised effectors in other fungal phytopathogens. In addition to modulating effector gene expression, PnPf2 may play a broader role in the establishment of a necrotrophic lifestyle by orchestrating the expression of genes associated with plant cell wall degradation and nutrient assimilation.

scholarly journals Ralstonia solanacearum Pectin Methylesterase Is Required for Growth on Methylated Pectin but Not for Bacterial Wilt Virulence

1998 ◽  
Vol 64 (12) ◽  
pp. 4918-4923 ◽  
Author(s):  
Julie Tans-Kersten ◽  
Yanfen Guan ◽  
Caitilyn Allen
Keyword(s):  
Cell Wall ◽  
Bacterial Wilt ◽  
Plant Cell Wall ◽  
Genomic Library ◽  
Response Regulator ◽  
Disease Process ◽  
Pectin Methylesterase ◽  
Wild Type ◽  
Cell Wall Degrading Enzymes

ABSTRACT Ralstonia (Pseudomonas)solanacearum causes bacterial wilt, a serious disease of many crop plants. The pathogen produces several extracellular plant cell wall-degrading enzymes, including polygalacturonases (PGs) and pectin methylesterase (Pme). Pme removes methyl groups from pectin, thereby facilitating subsequent breakdown of this cell wall component by PGs, which are known bacterial wilt virulence factors. R. solanacearum PGs could not degrade 93% methylated pectin unless the substrate was first demethylated by Pme, but as the degree of methylation of the pectin substrate decreased, PG activity increased. Primers derived from a published pme sequence generated an 800-bp DNA probe fragment, which identified Pme-encoding plasmids from a R. solanacearum genomic library. A pmechromosomal mutant had no detectable Pme activity in vitro and no longer grew on 93% methylated pectin as a carbon source. Curiously, the pme mutant, which had no detectable PG activity on highly methylated pectin, was just as virulent as the wild-type strain on tomato, eggplant (aubergine), and tobacco. Since PG activity is required for full virulence, this result suggests that the pectin in these particular hosts may not be highly methylated, or that the breakdown of highly methylated pectin is not a significant factor in the disease process in general. A positive response regulator of PG production called PehR was not required for wild-type Pme production. However, a mutant strain lacking PhcA, which is a global regulator of several virulence genes, produced no detectable Pme activity. Thus,pme expression is directly or indirectly regulated by PhcA but not by PehR.

scholarly journals Melanin Is Not Required for Turgor Generation but Enhances Cell-Wall Rigidity in Appressoria of the Corn Pathogen Colletotrichum graminicola

2014 ◽  
Vol 27 (4) ◽  
pp. 315-327 ◽  
Author(s):  
Nancy Ludwig ◽  
Marco Löhrer ◽  
Marcus Hempel ◽  
Sebastian Mathea ◽  
Ivo Schliebner ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell Wall ◽  
Fluorescent Protein ◽  
Quantitative Polymerase Chain Reaction ◽  
Turgor Pressure ◽  
Colletotrichum Graminicola ◽  
Cell Wall Degrading Enzymes ◽  
Melanin Biosynthesis ◽  
Successful Infection ◽  
Intact Leaves

The ascomycete and causative agent of maize anthracnose and stem rot, Colletotrichum graminicola, differentiates melanized infection cells called appressoria that are indispensable for breaching the plant cell wall. High concentrations of osmolytes accumulate within the appressorium, and the internal turgor pressure of up to 5.4 MPa provides sufficient force to penetrate the leaf epidermis directly. In order to assess the function of melanin in C. graminicola appressoria, we identified and characterized the polyketide synthase 1 (CgPKS1) gene which displayed high similarity to fungal polyketide synthases (PKS) involved in synthesis of 1,3,6,8-tetrahydronaphthalene, the first intermediate in melanin biosynthesis. Cgpks1 albino mutants created by targeted gene disruption were unable to penetrate intact leaves and ruptured frequently but, surprisingly, were able to penetrate ultrathin polytetrafluoroethylene membranes mimicking the plant surface. Nonmelanized Cgpks1 appressoria were sensitive to externally applied cell-wall-degrading enzymes whereas melanized appressoria were not affected. Expression studies using a truncated CgPKS1 fused to green fluorescent protein revealed fluorescence in immature appressoria and in setae, which is in agreement with transcript data obtained by RNA-Seq and quantitative polymerase chain reaction. Unexpectedly, surface scans of mutant and wild-type appressoria revealed considerable differences in cell-wall morphology. Melanization of appressoria is indispensable for successful infection of intact leaves. However, cell collapse experiments and analysis of the appressorial osmolyte content by Mach-Zehnder interferometry convincingly showed that melanin is not required for solute accumulation and turgor generation, thus questioning the role of melanin as a barrier for osmolytes in appressoria of C. graminicola.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

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