Oligosaccharide Elicitors and Their Receptors for Plant Defense Responses.

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.

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

International Journal of Molecular Sciences ◽

10.3390/ijms22084214 ◽

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.

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WRKY transcription factors and plant defense responses: latest discoveries and future prospects

Plant Cell Reports ◽

10.1007/s00299-021-02691-8 ◽

2021 ◽

Author(s):

Shabir H. Wani ◽

Shruti Anand ◽

Balwant Singh ◽

Abhishek Bohra ◽

Rohit Joshi

Keyword(s):

Transcription Factors ◽

Plant Defense ◽

Defense Responses ◽

Future Prospects ◽

Plant Defense Responses ◽

Wrky Transcription Factors

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

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.92.10.4134 ◽

1995 ◽

Vol 92 (10) ◽

pp. 4134-4137 ◽

Cited By ~ 102

Author(s):

Z. Chen ◽

J. Malamy ◽

J. Henning ◽

U. Conrath ◽

P. Sanchez-Casas ◽

...

Keyword(s):

Salicylic Acid ◽

Plant Defense ◽

Defense Responses ◽

Plant Defense Responses

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

Plant and Cell Physiology ◽

10.1093/oxfordjournals.pcp.a029327 ◽

1998 ◽

Vol 39 (11) ◽

pp. 1245-1249 ◽

Cited By ~ 28

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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Elicitor Recognition and Signal Transduction in Plant Defense Gene Activation

Zeitschrift für Naturforschung C ◽

10.1515/znc-1990-0601 ◽

1990 ◽

Vol 45 (6) ◽

pp. 569-575 ◽

Cited By ~ 56

Author(s):

Dierk Scheel ◽

Jane E. Parker

Keyword(s):

Signal Transduction ◽

Plant Defense ◽

Transcriptional Activation ◽

Molecular Mechanisms ◽

Plant Protection ◽

Plant Cells ◽

Defense Responses ◽

Plant Defense Responses ◽

Defense Genes ◽

Plant Defense Genes

Abstract Plants defend themselves against pathogen attack by activating a whole set of defense responses, most of them relying on transcriptional activation of plant defense genes. The same responses are induced by treatment of plant cells with elicitors released from the pathogen or from the plant surface. Several plant/elicitor combinations have been used successfully as experimental systems to investigate the molecular basis of plant defense responses. Receptor-like structures on the plasma membrane of plant cells appear to bind the elicitors. Thereby, intracellular signal transduction chains are initiated which finally result in the activation of plant defense genes. A better understanding of the molecular mechanisms of early processes in plant defense responses, as provided by these studies, may in the long term help to develop environmentally safe plant protection methods for agriculture.

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