scholarly journals Nanogram Amounts of Salicylic Acid Produced by the Rhizobacterium Pseudomonas aeruginosa 7NSK2 Activate the Systemic Acquired Resistance Pathway in Bean

1999 ◽  
Vol 12 (5) ◽  
pp. 450-458 ◽  
Author(s):  
Geert De Meyer ◽  
Kristof Capieau ◽  
Kris Audenaert ◽  
Antony Buchala ◽  
Jean-Pierre Métraux ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Salicylic Acid ◽  
Induced Resistance ◽  
Phenylalanine Ammonia Lyase ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Systemic Resistance ◽  
Resistance Pathway ◽  
Lyase Activity ◽  
Phenylalanine Ammonia Lyase Activity

Root colonization by specific nonpathogenic bacteria can induce a systemic resistance in plants to pathogen infections. In bean, this kind of systemic resistance can be induced by the rhizobacterium Pseudomonas aeruginosa 7NSK2 and depends on the production of salicylic acid by this strain. In a model with plants grown in perlite we demonstrated that Pseudomonas aeruginosa 7NSK2-induced resistance is equivalent to the inclusion of 1 nM salicylic acid in the nutrient solution and used the latter treatment to analyze the molecular basis of this phenomenon. Hydroponic feeding of 1 nM salicylic acid solutions induced phenylalanine ammonia-lyase activity in roots and increased free salicylic acid levels in leaves. Because pathogen-induced systemic acquired resistance involves similar changes it was concluded that 7NSK2-induced resistance is mediated by the systemic acquired resistance pathway. This conclusion was validated by analysis of phenylalanine ammonia-lyase activity in roots and of salicylic acid levels in leaves of soil-grown plants treated with Pseudomonas aeruginosa. The induction of systemic acquired resistance by nanogram amounts of salicylic acid is discussed with respect to long-distance signaling in systemic acquired resistance.

scholarly journals Induction of Systemic Resistance to Botrytis cinerea in Tomato by Pseudomonas aeruginosa 7NSK2: Role of Salicylic Acid, Pyochelin, and Pyocyanin

2002 ◽  
Vol 15 (11) ◽  
pp. 1147-1156 ◽  
Author(s):  
Kris Audenaert ◽  
Theresa Pattery ◽  
Pierre Cornelis ◽  
Monica Höfte
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Salicylic Acid ◽  
Botrytis Cinerea ◽  
Induced Resistance ◽  
Mammalian Cells ◽  
Cell Damage ◽  
Systemic Resistance ◽  
Wild Type ◽  
Induce Resistance

The rhizobacterium Pseudomonas aeruginosa 7NSK2 produces secondary metabolites such as pyochelin (Pch), its precursor salicylic acid (SA), and the phenazine compound pyocyanin. Both 7NSK2 and mutant KMPCH (Pch-negative, SA-positive) induced resistance to Botrytis cinerea in wild-type but not in transgenic NahG tomato. SA-negative mutants of both strains lost the capacity to induce resistance. On tomato roots, KMPCH produced SA and induced phenylalanine ammonia lyase activity, while this was not the case for 7NSK2. In 7NSK2, SA is probably very efficiently converted to Pch. However, Pch alone appeared not to be sufficient to induce resistance. In mammalian cells, Fe-Pch and pyocyanin can act synergistically to generate highly reactive hydroxyl radicals that cause cell damage. Reactive oxygen species are known to play an important role in plant defense. To study the role of pyocyanin in induced resistance, a pyocyanin-negative mutant of 7NSK2, PHZ1, was generated. PHZ1 is mutated in the phzM gene encoding an O-methyltransferase. PHZ1 was unable to induce resistance to B. cinerea, whereas complementation for pyocyanin production or co-inoculation with mutant 7NSK2-562 (Pch-negative, SA-negative, pyocyanin-positive) restored induced resistance. These results suggest that pyocyanin and Pch, rather than SA, are the determinants for induced resistance in wild-type P. aeruginosa 7NSK2.

scholarly journals Differential Effectiveness of Salicylate-Dependent and Jasmonate/Ethylene-Dependent Induced Resistance in Arabidopsis

2002 ◽  
Vol 15 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Jurriaan Ton ◽  
Johan A. Van Pelt ◽  
L. C. Van Loon ◽  
Corné M. J. Pieterse
Keyword(s):  
Induced Resistance ◽  
Xanthomonas Campestris ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Defense Responses ◽  
Alternaria Brassicicola ◽  
Systemic Resistance ◽  
Basal Resistance ◽  
Viral Pathogen ◽  
Differential Effectiveness

Salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) are each involved in the regulation of basal resistance against different pathogens. These three signals play important roles in induced resistance as well. SA is a key regulator of pathogen-induced systemic acquired resistance (SAR), whereas JA and ET are required for rhizobacteria-mediated induced systemic resistance (ISR). Both types of induced resistance are effective against a broad spectrum of pathogens. In this study, we compared the spectrum of effectiveness of SAR and ISR using an oomycete, a fungal, a bacterial, and a viral pathogen. In noninduced Arabidopsis plants, these pathogens are primarily resisted through either SA-dependent basal resistance (Peronospora parasitica and Turnip crinkle virus [TCV]), JA/ET-dependent basal resistance responses (Alternaria brassicicola), or a combination of SA-, JA-, and ET-dependent defenses (Xanthomonas campestris pv. armoraciae). Activation of ISR resulted in a significant level of protection against A. brassicicola, whereas SAR was ineffective against this pathogen. Conversely, activation of SAR resulted in a high level of protection against P. parasitica and TCV, whereas ISR conferred only weak and no protection against P. parasitica and TCV, respectively. Induction of SAR and ISR was equally effective against X. campestris pv. armoraciae. These results indicate that SAR is effective against pathogens that in noninduced plants are resisted through SA-dependent defenses, whereas ISR is effective against pathogens that in noninduced plants are resisted through JA/ET-dependent defenses. This suggests that SAR and ISR constitute a reinforcement of extant SA- or JA/ET-dependent basal defense responses, respectively.

Practical application of induced resistance to plant diseases: an appraisal of effectiveness under field conditions

2009 ◽  
Vol 147 (5) ◽  
pp. 523-535 ◽  
Author(s):  
D. R. WALTERS ◽  
J. M. FOUNTAINE
Keyword(s):  
Induced Resistance ◽  
Systemic Acquired Resistance ◽  
Regulatory Protein ◽  
Acquired Resistance ◽  
Crop Protection ◽  
Plant Growth Promoting Rhizobacteria ◽  
Plant Diseases ◽  
Systemic Resistance ◽  
Plant Parts ◽  
The Impact

SUMMARYPlants resist pathogen attack through a combination of constitutive and inducible defences. Different types of induced resistance have been defined based on differences in signalling pathways and spectra of effectiveness. Systemic acquired resistance (SAR) occurs in distal plant parts following localized infection by a necrotizing pathogen. It is controlled by a signalling pathway that depends upon the accumulation of salicylic acid (SA) and the regulatory protein NPR1. In contrast, induced systemic resistance (ISR) is promoted by selected strains of non-pathogenic plant growth-promoting rhizobacteria (PGPR). ISR functions independently of SA, but requires NPR1 and is regulated by jasmonic acid (JA) and ethylene (ET).Resistance can be induced by treatment with a variety of biotic and abiotic inducers. The resistance induced is broad spectrum and can be long-lasting, but is rarely complete, with most inducing agents providing between 0·20 and 0·85 disease control. In the field, expression of induced resistance is likely to be influenced by the environment, genotype, crop nutrition and the extent to which plants are already induced. Unfortunately, understanding of the impact of these influences on the expression of induced resistance is rudimentary. So too is understanding of how best to use induced resistance in practical crop protection. This situation will need to change if induced resistance is to fulfil its potential in crop protection.

scholarly journals Sulfur-Induced Resistance against Pseudomonas syringae pv. actinidiae via Triggering Salicylic Acid Signaling Pathway in Kiwifruit

2021 ◽  
Vol 22 (23) ◽  
pp. 12710
Author(s):  
Zhuzhu Zhang ◽  
Youhua Long ◽  
Xianhui Yin ◽  
Sen Yang
Keyword(s):  
Salicylic Acid ◽  
Signaling Pathway ◽  
Induced Resistance ◽  
Pseudomonas Syringae ◽  
Plant Disease Resistance ◽  
Plant Pathogens ◽  
Systemic Acquired Resistance ◽  
Lignin Content ◽  
Acquired Resistance ◽  
Salicylic Acid Signaling

Sulfur has been previously reported to modulate plant growth and exhibit significant anti-microbial activities. However, the mechanism underlying its diverse effects on plant pathogens has not been elucidated completely. The present study conducted the two-year field experiment of sulfur application to control kiwifruit canker from 2017 to 2018. For the first time, our study uncovered activation of plant disease resistance by salicylic acid after sulfur application in kiwifruit. The results indicated that when the sulfur concentration was 1.5–2.0 kg m−3, the induced effect of kiwifruit canker reached more than 70%. Meanwhile, a salicylic acid high lever was accompanied by the decline of jasmonic acid. Further analysis revealed the high expression of the defense gene, especially AcPR-1, which is a marker of the salicylic acid signaling pathway. Additionally, AcICS1, another critical gene of salicylic acid synthesis, was also highly expressed. All contributed to the synthesis of increasing salicylic acid content in kiwifruit leaves. Moreover, the first key lignin biosynthetic AcPAL gene was marked up-regulated. Thereafter, accumulation of lignin content in the kiwifruit stem and the higher deposition of lignin were visible in histochemical analysis. Moreover, the activity of the endochitinase activity of kiwifruit leaves increased significantly. We suggest that the sulfur-induced resistance against Pseudomonas syringae pv. actinidiae via salicylic activates systemic acquired resistance to enhance plant immune response in kiwifruit.

scholarly journals Salicylic Acid Produced by the Rhizobacterium Pseudomonas aeruginosa 7NSK2 Induces Resistance to Leaf Infection by Botrytis cinerea on Bean

1997 ◽  
Vol 87 (6) ◽  
pp. 588-593 ◽  
Author(s):  
Geert De Meyer ◽  
Monica Höfte
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Salicylic Acid ◽  
Botrytis Cinerea ◽  
Induced Resistance ◽  
Transcriptional Activity ◽  
Nutritional State ◽  
Systemic Resistance ◽  
Biosynthetic Genes ◽  
Bean Plants ◽  
Induction Of Resistance

Selected strains of nonpathogenic rhizobacteria can induce a systemic resistance in plants that is effective against various pathogens. In an assay with bean plants, we investigated which determinants of the rhizobacterium Pseudomonas aeruginosa 7NSK2 are important for induction of resistance to Botrytis cinerea. By varying the iron nutritional state of the bacterium at inoculation, it was demonstrated that induced resistance by P. aeruginosa 7NSK2 was iron-regulated. As P. aeruginosa 7NSK2 produces three siderophores under iron limitation, pyoverdin, pyochelin, and salicylic acid, we investigated the involvement of these iron-regulated metabolites in induced resistance by using mutants deficient in one or more siderophores. Results demonstrated that salicylic acid production was essential for induction of resistance to B. cinerea by P. aeruginosa 7NSK2 in bean and did not exclude a role for pyochelin. A role for pyoverdin, however, could not be demonstrated. Transcriptional activity of salicylic acid and pyochelin biosynthetic genes was detected during P. aeruginosa 7NSK2 colonization of bean. Moreover, the iron nutritional state at inoculation influenced the transcriptional activity of salicylic acid and pyochelin biosynthetic genes in the same way as it influenced induction of systemic resistance to B. cinerea.

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