scholarly journals Plant Metabolites in Plant Defense Against Pathogens

2020 ◽  
Author(s):  
Xóchitl S. Ramírez-Gómez ◽  
Sandra N. Jiménez-García ◽  
Vicente Beltrán Campos ◽  
Ma. Lourdes García Campos
Keyword(s):  
Plant Defense ◽  
Plant Metabolites

scholarly journals The plant defense signal galactinol is specifically used as a nutrient by the bacterial pathogen Agrobacterium fabrum

2018 ◽  
Vol 293 (21) ◽  
pp. 7930-7941 ◽  
Author(s):  
Thibault Meyer ◽  
Armelle Vigouroux ◽  
Magali Aumont-Nicaise ◽  
Gilles Comte ◽  
Ludovic Vial ◽  
...  
Keyword(s):  
Competitive Advantage ◽  
Plant Defense ◽  
Higher Plants ◽  
Bacterial Pathogen ◽  
Binding Mode ◽  
Plant Colonization ◽  
Plant Metabolites ◽  
Tomato Plants ◽  
Periplasmic Binding Proteins ◽  
Nanomolar Range

The bacterial plant pathogen Agrobacterium fabrum uses periplasmic-binding proteins (PBPs) along with ABC transporters to import a wide variety of plant molecules as nutrients. Nonetheless, how A. fabrum acquires plant metabolites is incompletely understood. Using genetic approaches and affinity measurements, we identified here the PBP MelB and its transporter as being responsible for the uptake of the raffinose family of oligosaccharides (RFO), which are the most widespread d-galactose–containing oligosaccharides in higher plants. We also found that the RFO precursor galactinol, recently described as a plant defense molecule, is imported into Agrobacterium via MelB with nanomolar range affinity. Structural analyses and binding mode comparisons of the X-ray structures of MelB in complex with raffinose, stachyose, galactinol, galactose, and melibiose (a raffinose degradation product) revealed how MelB recognizes the nonreducing end galactose common to all these ligands and that MelB has a strong preference for a two-unit sugar ligand. Of note, MelB conferred a competitive advantage to A. fabrum in colonizing the rhizosphere of tomato plants. Our integrative work highlights the structural and functional characteristics of melibiose and galactinol assimilation by A. fabrum, leading to a competitive advantage for these bacteria in the rhizosphere. We propose that the PBP MelB, which is highly conserved among both symbionts and pathogens from Rhizobiace family, is a major trait in these bacteria required for early steps of plant colonization.

scholarly journals The Plant-Stress Metabolites, Hexanoic Aacid and Melatonin, Are Potential “Vaccines” for Plant Health Promotion

2021 ◽  
Vol 37 (5) ◽  
pp. 415-427
Author(s):  
Anne J. Anderson ◽  
Young Cheol Kim
Keyword(s):  
Plant Defense ◽  
Abiotic Stresses ◽  
Plant Stress ◽  
Defense Responses ◽  
Hexanoic Acid ◽  
Microbial Pathogens ◽  
Plant Metabolites ◽  
Protective Mechanisms ◽  
Stress Metabolites ◽  
Rapid Activation

A plethora of compounds stimulate protective mechanisms in plants against microbial pathogens and abiotic stresses. Some defense activators are synthetic compounds and trigger responses only in certain protective pathways, such as activation of defenses under regulation by the plant regulator, salicylic acid (SA). This review discusses the potential of naturally occurring plant metabolites as primers for defense responses in the plant. The production of the metabolites, hexanoic acid and melatonin, in plants means they are consumed when plants are eaten as foods. Both metabolites prime stronger and more rapid activation of plant defense upon subsequent stress. Because these metabolites trigger protective measures in the plant they can be considered as “vaccines” to promote plant vigor. Hexanoic acid and melatonin instigate systemic changes in plant metabolism associated with both of the major defense pathways, those regulated by SA- and jasmonic acid (JA). These two pathways are well studied because of their induction by different microbial triggers: necrosis-causing microbial pathogens induce the SA pathway whereas colonization by beneficial microbes stimulates the JA pathway. The plant’s responses to the two metabolites, however, are not identical with a major difference being a characterized growth response with melatonin but not hexanoic acid. As primers for plant defense, hexanoic acid and melatonin have the potential to be successfully integrated into vaccination-like strategies to protect plants against diseases and abiotic stresses that do not involve man-made chemicals.

scholarly journals Role of Saponins in Plant Defense Against Specialist Herbivores

Molecules ◽  
2019 ◽  
Vol 24 (11) ◽  
pp. 2067 ◽  
Author(s):  
Mubasher Hussain ◽  
Biswojit Debnath ◽  
Muhammad Qasim ◽  
Bamisope Steve Bamisile ◽  
Waqar Islam ◽  
...  
Keyword(s):  
Plant Defense ◽  
Host Plant ◽  
Larval Survival ◽  
Bioactive Molecules ◽  
Plant Metabolites ◽  
Specialist Herbivore ◽  
Triterpenoid Saponins ◽  
Secondary Plant Metabolites ◽  
Specialist Herbivores

The diamondback moth (DBM), Plutella xylostella (Lepidoptera: Plutellidae) is a very destructive crucifer-specialized pest that has resulted in significant crop losses worldwide. DBM is well attracted to glucosinolates (which act as fingerprints and essential for herbivores in host plant recognition) containing crucifers such as wintercress, Barbarea vulgaris (Brassicaceae) despite poor larval survival on it due to high-to-low concentration of saponins and generally to other plants in the genus Barbarea. B. vulgaris build up resistance against DBM and other herbivorous insects using glucosinulates which are used in plant defense. Aside glucosinolates, Barbarea genus also contains triterpenoid saponins, which are toxic to insects and act as feeding deterrents for plant specialist herbivores (such as DBM). Previous studies have found interesting relationship between the host plant and secondary metabolite contents, which indicate that attraction or resistance to specialist herbivore DBM, is due to higher concentrations of glucosinolates and saponins in younger leaves in contrast to the older leaves of Barbarea genus. As a response to this phenomenon, herbivores as DBM has developed a strategy of defense against these plant biochemicals. Because there is a lack of full knowledge in understanding bioactive molecules (such as saponins) role in plant defense against plant herbivores. Thus, in this review, we discuss the role of secondary plant metabolites in plant defense mechanisms against the specialist herbivores. In the future, trials by plant breeders could aim at transferring these bioactive molecules against herbivore to cash crops.

Plant defense against pathogens

AccessScience ◽  
2015 ◽  
Keyword(s):  
Plant Defense
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