scholarly journals The Role of Arabinogalactan Type II Degradation in Plant-Microbe Interactions

2021 ◽  
Vol 12 ◽  
Author(s):  
Maria Guadalupe Villa-Rivera ◽  
Horacio Cano-Camacho ◽  
Everardo López-Romero ◽  
María Guadalupe Zavala-Páramo
Keyword(s):  
Cell Wall ◽  
Plant Defense ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Degradation Products ◽  
Hydrolytic Enzymes ◽  
Pathogenic Fungi ◽  
Plant Interactions ◽  
Root Tips ◽  
Microbe Interactions

Arabinogalactans (AGs) are structural polysaccharides of the plant cell wall. A small proportion of the AGs are associated with hemicellulose and pectin. Furthermore, AGs are associated with proteins forming the so-called arabinogalactan proteins (AGPs), which can be found in the plant cell wall or attached through a glycosylphosphatidylinositol (GPI) anchor to the plasma membrane. AGPs are a family of highly glycosylated proteins grouped with cell wall proteins rich in hydroxyproline. These glycoproteins have important and diverse functions in plants, such as growth, cellular differentiation, signaling, and microbe-plant interactions, and several reports suggest that carbohydrate components are crucial for AGP functions. In beneficial plant-microbe interactions, AGPs attract symbiotic species of fungi or bacteria, promote the development of infectious structures and the colonization of root tips, and furthermore, these interactions can activate plant defense mechanisms. On the other hand, plants secrete and accumulate AGPs at infection sites, creating cross-links with pectin. As part of the plant cell wall degradation machinery, beneficial and pathogenic fungi and bacteria can produce the enzymes necessary for the complete depolymerization of AGs including endo-β-(1,3), β-(1,4) and β-(1,6)-galactanases, β-(1,3/1,6) galactanases, α-L-arabinofuranosidases, β-L-arabinopyranosidases, and β-D-glucuronidases. These hydrolytic enzymes are secreted during plant-pathogen interactions and could have implications for the function of AGPs. It has been proposed that AGPs could prevent infection by pathogenic microorganisms because their degradation products generated by hydrolytic enzymes of pathogens function as damage-associated molecular patterns (DAMPs) eliciting the plant defense response. In this review, we describe the structure and function of AGs and AGPs as components of the plant cell wall. Additionally, we describe the set of enzymes secreted by microorganisms to degrade AGs from AGPs and its possible implication for plant-microbe interactions.

scholarly journals Arsenal of plant cell wall degrading enzymes reflects host preference among plant pathogenic fungi

2011 ◽  
Vol 4 (1) ◽  
pp. 4 ◽  
Author(s):  
Brian C King ◽  
Katrina D Waxman ◽  
Nicholas V Nenni ◽  
Larry P Walker ◽  
Gary C Bergstrom ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Host Preference ◽  
Plant Cell Wall ◽  
Pathogenic Fungi ◽  
Plant Pathogenic Fungi ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes

scholarly journals Comparative Analysis of Herbaceous and Woody Cell Wall Digestibility by Pathogenic Fungi

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7220
Author(s):  
Yanhua Dou ◽  
Yan Yang ◽  
Nitesh Kumar Mund ◽  
Yanping Wei ◽  
Yisong Liu ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Fungal Pathogens ◽  
Plant Cell Wall ◽  
Apple Tree ◽  
Plant Biomass ◽  
Genomic Analysis ◽  
Pathogenic Fungi ◽  
Cell Wall Degrading Enzymes ◽  
Enzyme Activity Assay

Fungal pathogens have evolved combinations of plant cell-wall-degrading enzymes (PCWDEs) to deconstruct host plant cell walls (PCWs). An understanding of this process is hoped to create a basis for improving plant biomass conversion efficiency into sustainable biofuels and bioproducts. Here, an approach integrating enzyme activity assay, biomass pretreatment, field emission scanning electron microscopy (FESEM), and genomic analysis of PCWDEs were applied to examine digestibility or degradability of selected woody and herbaceous biomass by pathogenic fungi. Preferred hydrolysis of apple tree branch, rapeseed straw, or wheat straw were observed by the apple-tree-specific pathogen Valsa mali, the rapeseed pathogen Sclerotinia sclerotiorum, and the wheat pathogen Rhizoctonia cerealis, respectively. Delignification by peracetic acid (PAA) pretreatment increased PCW digestibility, and the increase was generally more profound with non-host than host PCW substrates. Hemicellulase pretreatment slightly reduced or had no effect on hemicellulose content in the PCW substrates tested; however, the pretreatment significantly changed hydrolytic preferences of the selected pathogens, indicating a role of hemicellulose branching in PCW digestibility. Cellulose organization appears to also impact digestibility of host PCWs, as reflected by differences in cellulose microfibril organization in woody and herbaceous PCWs and variation in cellulose-binding domain organization in cellulases of pathogenic fungi, which is known to influence enzyme access to cellulose. Taken together, this study highlighted the importance of chemical structure of both hemicelluloses and cellulose in host PCW digestibility by fungal pathogens.

scholarly journals Insights into Plant Cell Wall Degradation from the Genome Sequence of the Soil Bacterium Cellvibrio japonicus

2008 ◽  
Vol 190 (15) ◽  
pp. 5455-5463 ◽  
Author(s):  
Robert T. DeBoy ◽  
Emmanuel F. Mongodin ◽  
Derrick E. Fouts ◽  
Louise E. Tailford ◽  
Hoda Khouri ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Hydrolytic Enzymes ◽  
Soil Bacterium ◽  
Glycoside Hydrolases ◽  
Carbohydrate Binding ◽  
Carbohydrate Binding Modules ◽  
Cellvibrio Japonicus ◽  
And Storage

ABSTRACT The plant cell wall, which consists of a highly complex array of interconnecting polysaccharides, is the most abundant source of organic carbon in the biosphere. Microorganisms that degrade the plant cell wall synthesize an extensive portfolio of hydrolytic enzymes that display highly complex molecular architectures. To unravel the intricate repertoire of plant cell wall-degrading enzymes synthesized by the saprophytic soil bacterium Cellvibrio japonicus, we sequenced and analyzed its genome, which predicts that the bacterium contains the complete repertoire of enzymes required to degrade plant cell wall and storage polysaccharides. Approximately one-third of these putative proteins (57) are predicted to contain carbohydrate binding modules derived from 13 of the 49 known families. Sequence analysis reveals approximately 130 predicted glycoside hydrolases that target the major structural and storage plant polysaccharides. In common with that of the colonic prokaryote Bacteroides thetaiotaomicron, the genome of C. japonicus is predicted to encode a large number of GH43 enzymes, suggesting that the extensive arabinose decorations appended to pectins and xylans may represent a major nutrient source, not just for intestinal bacteria but also for microorganisms that occupy terrestrial ecosystems. The results presented here predict that C. japonicus possesses an extensive range of glycoside hydrolases, lyases, and esterases. Most importantly, the genome of C. japonicus is remarkably similar to that of the gram-negative marine bacterium, Saccharophagus degradans 2-40T. Approximately 50% of the predicted C. japonicus plant-degradative apparatus appears to be shared with S. degradans, consistent with the utilization of plant-derived complex carbohydrates as a major substrate by both organisms.

scholarly journals The Phytophthora infestans Haustorium Is a Site for Secretion of Diverse Classes of Infection-Associated Proteins

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Shumei Wang ◽  
Lydia Welsh ◽  
Peter Thorpe ◽  
Stephen C. Whisson ◽  
Petra C. Boevink ◽  
...  
Keyword(s):  
Cell Wall ◽  
Phytophthora Infestans ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Extracellular Proteins ◽  
Host Cells ◽  
Cysteine Protease Inhibitor ◽  
Plant Interactions ◽  
Content Type

ABSTRACT The oomycete potato blight pathogen Phytophthora infestans secretes a diverse set of proteins to manipulate host plant immunity. However, there is limited knowledge about how and where they are secreted during infection. Here we used the endoplasmic reticulum (ER)-to-Golgi secretion pathway inhibitor brefeldin A (BFA) in combination with liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) to identify extracellular proteins from P. infestans that were conventionally secreted from in vitro-cultured hyphae. We identified 19 proteins with predicted signal peptides that potentially influence plant interactions for which secretion was attenuated by BFA. In addition to inhibition by the apoplastic effector EPIC1, a cysteine protease inhibitor, we show that secretion of the cell wall-degrading pectinesterase enzyme PE1 and the microbe-associated molecular pattern (MAMP)-like elicitin INF4 was inhibited by BFA in vitro and in planta, demonstrating that these proteins are secreted by the conventional, Golgi-mediated pathway. For comparison, secretion of a cytoplasmic RXLR (Arg-[any amino acid]-Leu-Arg) effector, Pi22926, was not inhibited by BFA. During infection, whereas INF4 accumulated outside the plant cell, RXLR effector Pi22926 entered the plant cell and accumulated in the nucleus. The P. infestans effectors, the PE1 enzyme, and INF4 were all secreted from haustoria, pathogen structures that penetrate the plant cell wall to form an intimate interaction with the host plasma membrane. Our findings show the haustorium to be a major site of both conventional and nonconventional secretion of proteins with diverse functions during infection. IMPORTANCE There are many different classes of proteins secreted from Phytophthora infestans that may influence or facilitate infection. Elucidating where and how they are secreted during infection is an important step toward developing methods to control their delivery processes. We used an inhibitor of conventional secretion to identify the following different classes of infection-associated extracellular proteins: cell wall-degrading and cell wall-modifying enzymes, microbe-associated molecular pattern-like proteins that may elicit immune responses, and apoplastic effectors that are predicted to suppress immunity. In contrast, secretion of a cytoplasmic effector that is translocated into host cells is nonconventional, as it is insensitive to inhibitor treatment. This evidence further supports the finding that proteins that are active in the apoplast and effector proteins that are active in the host cytoplasm are differentially secreted by P. infestans. Critically, it demonstrates that a disease-specific developmental structure, the haustorium, is a major secretion site for diverse protein classes during infection.

scholarly journals Activating Intrinsic Carbohydrate-Active Enzymes of the Smut Fungus Ustilago maydis for the Degradation of Plant Cell Wall Components

2016 ◽  
Vol 82 (17) ◽  
pp. 5174-5185 ◽  
Author(s):  
Elena Geiser ◽  
Michèle Reindl ◽  
Lars M. Blank ◽  
Michael Feldbrügge ◽  
Nick Wierckx ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Hydrolytic Enzymes ◽  
Value Added ◽  
Ustilago Maydis ◽  
Smut Fungus ◽  
Content Type ◽  
Cell Wall Components ◽  
Wall Components

ABSTRACTThe microbial conversion of plant biomass to valuable products in a consolidated bioprocess could greatly increase the ecologic and economic impact of a biorefinery. Current strategies for hydrolyzing plant material mostly rely on the external application of carbohydrate-active enzymes (CAZymes). Alternatively, production organisms can be engineered to secrete CAZymes to reduce the reliance on externally added enzymes. Plant-pathogenic fungi have a vast repertoire of hydrolytic enzymes to sustain their lifestyle, but expression of the corresponding genes is usually highly regulated and restricted to the pathogenic phase. Here, we present a new strategy in using the biotrophic smut fungusUstilago maydisfor the degradation of plant cell wall components by activating its intrinsic enzyme potential during axenic growth. This fungal model organism is fully equipped with hydrolytic enzymes, and moreover, it naturally produces value-added substances, such as organic acids and biosurfactants. To achieve the deregulated expression of hydrolytic enzymes during the industrially relevant yeast-like growth in axenic culture, the native promoters of the respective genes were replaced by constitutively active synthetic promoters. This led to an enhanced conversion of xylan, cellobiose, and carboxymethyl cellulose to fermentable sugars. Moreover, a combination of strains with activated endoglucanase and β-glucanase increased the release of glucose from carboxymethyl cellulose and regenerated amorphous cellulose, suggesting that mixed cultivations could be a means for degrading more complex substrates in the future. In summary, this proof of principle demonstrates the potential applicability of activating the expression of native CAZymes from phytopathogens in a biocatalytic process.IMPORTANCEThis study describes basic experiments that aim at the degradation of plant cell wall components by the smut fungusUstilago maydis. As a plant pathogen, this fungus contains a set of lignocellulose-degrading enzymes that may be suited for biomass degradation. However, its hydrolytic enzymes are specifically expressed only during plant infection. Here, we provide the proof of principle that these intrinsic enzymes can be synthetically activated during the industrially relevant yeast-like growth. The fungus is known to naturally synthesize valuable compounds, such as itaconate or glycolipids. Therefore, it could be suited for use in a consolidated bioprocess in which more complex and natural substrates are simultaneously converted to fermentable sugars and to value-added compounds in the future.

scholarly journals Microbial Endoxylanases: Effective Weapons to Breach the Plant Cell-Wall Barrier or, Rather, Triggers of Plant Defense Systems?

2006 ◽  
Vol 19 (10) ◽  
pp. 1072-1081 ◽  
Author(s):  
Tim Beliën ◽  
Steven Van Campenhout ◽  
Johan Robben ◽  
Guido Volckaert
Keyword(s):  
Cell Wall ◽  
Plant Defense ◽  
Plant Cell ◽  
Cell Walls ◽  
Defense Mechanisms ◽  
Plant Cell Wall ◽  
Cell Wall Degrading Enzymes ◽  
Defense Systems ◽  
Xylanase Inhibitor

Endo-β-1,4-xylanases (EC 3.2.1.8) are key enzymes in the degradation of xylan, the predominant hemicellulose in the cell walls of plants and the second most abundant polysaccharide on earth. A number of endoxylanases are produced by microbial phytopathogens responsible for severe crop losses. These enzymes are considered to play an important role in phytopathogenesis, as they provide essential means to the attacking organism to break through the plant cell wall. Plants have evolved numerous defense mechanisms to protect themselves against invading pathogens, amongst which are proteinaceous inhibitors of cell wall-degrading enzymes. These defense mechanisms are triggered when a pathogen-derived elicitor is recognized by the plant. In this review, the diverse aspects of endoxylanases in promoting virulence and in eliciting plant defense systems are highlighted. Furthermore, the role of the relatively recently discovered cereal endoxylanase inhibitor families TAXI (Triticum aestivum xylanase inhibitor) and XIP (xylanase inhibitor protein) in plant defense is discussed.

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