scholarly journals Cyclic Lipopeptides of Bacillus amyloliquefaciens subsp. plantarum Colonizing the Lettuce Rhizosphere Enhance Plant Defense Responses Toward the Bottom Rot Pathogen Rhizoctonia solani

2015 ◽  
Vol 28 (9) ◽  
pp. 984-995 ◽  
Author(s):  
Soumitra Paul Chowdhury ◽  
Jenny Uhl ◽  
Rita Grosch ◽  
Sylvia Alquéres ◽  
Sabrina Pittroff ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Plant Defense ◽  
Bacillus Amyloliquefaciens ◽  
Defense Responses ◽  
Disease Suppression ◽  
Plant Defense Responses ◽  
Defense Gene Expression ◽  
Defense Gene ◽  
Pathogen Challenge ◽  
Bottom Rot

The commercially available inoculant Bacillus amyloliquefaciens FZB42 is able to considerably reduce lettuce bottom rot caused by Rhizoctonia solani. To understand the interaction between FZB42 and R. solani in the rhizosphere of lettuce, we used an axenic system with lettuce bacterized with FZB42 and inoculated with R. solani. Confocal laser scanning microscopy showed that FZB42 could delay the initial establishment of R. solani on the plants. To show which secondary metabolites of FZB42 are produced under these in-situ conditions, we developed an ultra-high performance liquid chromatography coupled to time of flight mass spectrometry–based method and identified surfactin, fengycin, and bacillomycin D in the lettuce rhizosphere. We hypothesized that lipopeptides and polyketides play a role in enhancing the plant defense responses in addition to the direct antagonistic effect toward R. solani and used a quantitative real-time polymerase chain reaction–based assay for marker genes involved in defense signaling pathways in lettuce. A significant higher expression of PDF 1.2 observed in the bacterized plants in response to subsequent pathogen challenge showed that FZB42 could enhance the lettuce defense response toward the fungal pathogen. To identify if surfactin or other nonribosomally synthesized secondary metabolites could elicit the observed enhanced defense gene expression, we examined two mutants of FZB42 deficient in production of surfactin and the lipopetides and polyketides, by expression analysis and pot experiments. In the absence of surfactin and other nonribosomally synthesized secondary metabolites, there was no enhanced PDF 1.2–mediated response to the pathogen challenge. Pot experiment results showed that the mutants failed to reduce disease incidence in lettuce as compared with the FZB42 wild type, indicating, that surfactin as well as other nonribosomally synthesized secondary metabolites play a role in the actual disease suppression and on lettuce health. In conclusion, our study showed that nonribosomally synthesized secondary metabolites of FZB42 are actually produced in the lettuce rhizosphere and contribute to the disease suppression by mediating plant defense gene expression toward the pathogen R. solani.

scholarly journals A small cysteine-rich phytotoxic protein of Phytophthora capsici functions as both plant defense elicitor and virulence factor

2021 ◽  
Author(s):  
Zi-Hui Zhang ◽  
Jinghao Jin ◽  
Gui-Lin Sheng ◽  
Yu-Ping Xing ◽  
Wang Liu ◽  
...  
Keyword(s):  
Plant Defense ◽  
Virulence Factor ◽  
Phytophthora Capsici ◽  
Ectopic Expression ◽  
Defense Responses ◽  
Phytophthora Species ◽  
Plant Interactions ◽  
Defense Gene Expression ◽  
Callose Deposition ◽  
Defense Gene

Small cysteine-rich (SCR) proteins including fungal avirulence proteins play important roles in the pathogen-plant interactions. SCR protein-encoding genes have been discovered in the genomes of Phytophthora pathogens, but their functions during the pathogenesis remain obscure. Here, we report the characterization of one Phytophthora capsici SCR protein, namely SCR82 with similarity to Phytophthora cactorum phytotoxic protein PcF. The scr82 gene has 10 allelic sequences in the P. capsici population. Homologues of SCR82 were not identified in fungi or other organisms but in Phytophthora relative species. Initially scr82 was weakly expressed during the mycelium, sporangium and zoospore stages, but quickly upregulated when the infection initiated. Both ectopic expression of SCR82 and recombinant yeast-expressed protein (rSCR82) caused cell death on tomato leaves. Upon treatment, rSCR82 induced plant defense responses including the induction of defense gene expression, reactive oxygen species burst and callose deposition. Knockout of scr82 in P. capsici by CRISPR/Cas9 severely impaired its virulence on host plants and reduced significantly its resistance againstoxidative stress. Inversely, its overexpression increased the pathogen’s virulence and tolerance to oxidative stress. Our results collectively demonstrate that SCR82 functions as both an important virulence factor and plant defense elicitor, which is conserved across Phytophthora species.

Application of Chitosan in Plant Defense Responses to Biotic and Abiotic Stresses

2020 ◽  
Author(s):  
Wasinee Pongprayoon ◽  
Thanapoom Siringam ◽  
Atikorn Panya ◽  
Sittiruk Roytrakul
Keyword(s):  
Secondary Metabolites ◽  
Plant Growth ◽  
Plant Defense ◽  
Abiotic Stresses ◽  
Proteinase Inhibitors ◽  
Signal Transduction Pathway ◽  
Defense Responses ◽  
Plant Responses ◽  
Plant Defense Responses ◽  
Biotic And Abiotic Stress

Chitosan, a copolymer of N-acetyl-D-glucosamine and D-glucosamine, which possesses properties that make it useful in various fields, is produced by the deacetylation of chitin derivatives. It is used in agriculture as a biostimulant for plant growth and protection, it also induces several responsive genes, proteins, and secondary metabolites in plants. Chitosan elicits a signal transduction pathway and transduces secondary molecules such as hydrogen peroxide and nitric oxide. Under biotic stress, chitosan can stimulate phytoalexins, pathogenesis-related proteins, and proteinase inhibitors. Pretreatment of chitosan before exposure to abiotic stresses (drought, salt, and heat) induces plant growth, production of antioxidant enzymes, secondary metabolites, and abscisic acid (ABA). It also causes changes in physiology, biochemistry, and molecular biology of the plant cells. However, plant responses depend on different chitosan-based structures, concentrations, species, and developmental stages. This review collects updated information on chitosan applications, particularly in plant defense responses to biotic and abiotic stress conditions.

scholarly journals An efficient direct screening system for microorganisms that activate plant immune responses based on plant–microbe interactions using cultured plant cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mari Kurokawa ◽  
Masataka Nakano ◽  
Nobutaka Kitahata ◽  
Kazuyuki Kuchitsu ◽  
Toshiki Furuya
Keyword(s):  
Immune Responses ◽  
Plant Defense ◽  
Pseudomonas Syringae ◽  
Large Scale ◽  
Plant Cells ◽  
Defense Responses ◽  
Root Tip ◽  
General Strategy ◽  
Plant Defense Responses ◽  
Microbe Interactions

AbstractMicroorganisms that activate plant immune responses have attracted considerable attention as potential biocontrol agents in agriculture because they could reduce agrochemical use. However, conventional methods to screen for such microorganisms using whole plants and pathogens are generally laborious and time consuming. Here, we describe a general strategy using cultured plant cells to identify microorganisms that activate plant defense responses based on plant–microbe interactions. Microbial cells were incubated with tobacco BY-2 cells, followed by treatment with cryptogein, a proteinaceous elicitor of tobacco immune responses secreted by an oomycete. Cryptogein-induced production of reactive oxygen species (ROS) in BY-2 cells served as a marker to evaluate the potential of microorganisms to activate plant defense responses. Twenty-nine bacterial strains isolated from the interior of Brassica rapa var. perviridis plants were screened, and 8 strains that enhanced cryptogein-induced ROS production in BY-2 cells were selected. Following application of these strains to the root tip of Arabidopsis seedlings, two strains, Delftia sp. BR1R-2 and Arthrobacter sp. BR2S-6, were found to induce whole-plant resistance to bacterial pathogens (Pseudomonas syringae pv. tomato DC3000 and Pectobacterium carotovora subsp. carotovora NBRC 14082). Pathogen-induced expression of plant defense-related genes (PR-1, PR-5, and PDF1.2) was enhanced by the pretreatment with strain BR1R-2. This cell–cell interaction-based platform is readily applicable to large-scale screening for microorganisms that enhance plant defense responses under various environmental conditions.

scholarly journals Method for the Production and Purification of Plant Immuno-Active Xylanase from Trichoderma

2021 ◽  
Vol 22 (8) ◽  
pp. 4214
Author(s):  
Gautam Anand ◽  
Meirav Leibman-Markus ◽  
Dorin Elkabetz ◽  
Maya Bar
Keyword(s):  
Immune System ◽  
Plant Defense ◽  
Plant Immunity ◽  
Xylanase Activity ◽  
Hydrolytic Enzymes ◽  
Adaptive Immune System ◽  
Defense Responses ◽  
Plant Defense Responses ◽  
Xylanase Production ◽  
Ideal System

Plants lack a circulating adaptive immune system to protect themselves against pathogens. Therefore, they have evolved an innate immune system based upon complicated and efficient defense mechanisms, either constitutive or inducible. Plant defense responses are triggered by elicitors such as microbe-associated molecular patterns (MAMPs). These components are recognized by pattern recognition receptors (PRRs) which include plant cell surface receptors. Upon recognition, PRRs trigger pattern-triggered immunity (PTI). Ethylene Inducing Xylanase (EIX) is a fungal MAMP protein from the plant-growth-promoting fungi (PGPF)–Trichoderma. It elicits plant defense responses in tobacco (Nicotiana tabacum) and tomato (Solanum lycopersicum), making it an excellent tool in the studies of plant immunity. Xylanases such as EIX are hydrolytic enzymes that act on xylan in hemicellulose. There are two types of xylanases: the endo-1, 4-β-xylanases that hydrolyze within the xylan structure, and the β-d-xylosidases that hydrolyze the ends of the xylan chain. Xylanases are mainly synthesized by fungi and bacteria. Filamentous fungi produce xylanases in high amounts and secrete them in liquid cultures, making them an ideal system for xylanase purification. Here, we describe a method for cost- and yield-effective xylanase production from Trichoderma using wheat bran as a growth substrate. Xylanase produced by this method possessed xylanase activity and immunogenic activity, effectively inducing a hypersensitive response, ethylene biosynthesis, and ROS burst.

scholarly journals Induction, modification, and transduction of the salicylic acid signal in plant defense responses.

1995 ◽  
Vol 92 (10) ◽  
pp. 4134-4137 ◽  
Author(s):  
Z. Chen ◽  
J. Malamy ◽  
J. Henning ◽  
U. Conrath ◽  
P. Sanchez-Casas ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Plant Defense ◽  
Defense Responses ◽  
Plant Defense Responses

scholarly journals Interaction between Cell Wall and Plasma Membrane via RGD Motif is Implicated in Plant Defense Responses

1998 ◽  
Vol 39 (11) ◽  
pp. 1245-1249 ◽  
Author(s):  
A. Kiba ◽  
M. Sugimoto ◽  
K. Toyoda ◽  
Y. Ichinose ◽  
T. Yamada ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Plant Defense ◽  
Defense Responses ◽  
Plant Defense Responses ◽  
Rgd Motif
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