Entomopathogenic nematodes induce systemic resistance in tomato against Spodoptera exigua, Bemisia tabaci and Pseudomonas syringae

2016 ◽  
Vol 93 ◽  
pp. 24-29 ◽  
Author(s):  
Ruisheng An ◽  
Diego Orellana ◽  
Larry P. Phelan ◽  
Luis Cañas ◽  
Parwinder S. Grewal
Plants ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1020
Author(s):  
Helena Martin-Rivilla ◽  
F. Javier Gutierrez-Mañero ◽  
Ana Gradillas ◽  
Miguel O. P. Navarro ◽  
Galdino Andrade ◽  
...  

In this work, the metabolic elicitors extracted from the beneficial rhizobacterium Pseudomonas fluorescens N 21.4 were sequentially fragmented by vacuum liquid chromatography to isolate, purify and identify the compounds responsible for the extraordinary capacities of this strain to induce systemic resistance and to elicit secondary defensive metabolism in diverse plant species. To check if the fractions sequentially obtained were able to increase the synthesis of isoflavones and if, therefore, they still maintained the eliciting capacity of the live strain, rapid and controlled experiments were done with soybean seeds. The optimal action concentration of the fractions was established and all of them elicited isoflavone secondary metabolism—the fractions that had been extracted with n-hexane being more effective. The purest fraction was the one with the highest eliciting capacity and was also tested in Arabidopsis thaliana seedlings to induce systemic resistance against the pathogen Pseudomonas syringae pv. tomato DC 3000. This fraction was then analyzed by UHPLC/ESI–QTOF–MS, and an alkaloid, two amino lipids, three arylalkylamines and a terpenoid were tentatively identified. These identified compounds could be part of commercial plant inoculants of biological and sustainable origin to be applied in crops, due to their potential to enhance the plant immune response and since many of them have putative antibiotic and/or antifungal potential.


2015 ◽  
Vol 68 ◽  
pp. 443-443
Author(s):  
C.H. Stark ◽  
R.A. Hill ◽  
N. Cummings ◽  
J-H. Li

The kiwifruit disease Pseudomonas syringae pv actinidiae (Psa) was first identified in New Zealand in 2010 and currently affects over 85 of the countrys kiwifruit orchard area This research focused on root endophytic Trichoderma as a biological control option for Psa as these fungi can limit the damaging effects of pathogens through antibiotic metabolites induce systemic resistance and improve plant health Promising biocontrol isolates were identified by inoculating kiwifruit with Trichoderma under controlled conditions and in the field before exposing them to Psa The mixture TriMix1 emerged as one of the best performing treatments consistently lowering disease incidence and increasing kiwifruit seedling longevity To assess persistence in kiwifruit roots and determine the best method to apply TriMix1 into existing orchards endophytic fungi were reisolated from kiwifruit roots at two organic NZ kiwifruit orchards following four treatments Trichoderma root application with (N) and without nutrient solution (T); surface application with vermicompost (V); untreated control (C) While similar numbers of Trichoderma were isolated from the two sites treatment effects were significant and treatments T V and N increased Trichoderma counts compared to the untreated control Inoculation of older orchard vines using a suitable application method facilitates the establishment of a strong root endophytic Trichoderma community that can improve plant health


2019 ◽  
Author(s):  
Kishore Vishwanathan ◽  
Krzysztof Zienkiewicz ◽  
Yang Liu ◽  
Dennis Janz ◽  
Ivo Feussner ◽  
...  

ABSTRACTBelow-ground microbes can induce systemic resistance (ISR) against foliar pests and pathogens on diverse plant hosts. The prevalence of ISR among plant-microbe-pest systems raises the question of host specificity in microbial induction of ISR. To test whether ISR is limited by plant host range, we tested the ISR-inducing ectomycorrhizal (ECM) fungus Laccaria bicolor on the non-mycorrhizal plant Arabidopsis. We found that root inoculation with L. bicolor triggered ISR against the insect herbivore Trichoplusia ni and induced systemic susceptibility (ISS) against the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 (Pto). We found that L. bicolor-triggered ISR against T. ni was dependent on jasmonic acid (JA) signaling and salicylic acid (SA) biosynthesis and signaling. We found that heat killed L. bicolor and chitin are sufficient to trigger ISR against T. ni and ISS against Pto and that the chitin receptor CERK1 is necessary for L. bicolor-mediated effects on systemic immunity. Collectively our findings suggest that some ISR responses might not require intimate co-evolution of host and microbe, but rather might be the result of root perception of conserved microbial signals.


2008 ◽  
Vol 98 (6) ◽  
pp. 666-672 ◽  
Author(s):  
J. Barriuso ◽  
B. Ramos Solano ◽  
F. J. Gutiérrez Mañero

The ability of four plant growth-promoting rhizobacteria, isolated in a previous study, to induce systemic resistance on Arabidopsis thaliana Col 0 against biotic and abiotic stress was evaluated. All the bacteria enhanced protection against the foliar pathogen Pseudomonas syringae DC3000 and increased plant tolerance to salt stress (NaCl 60 mM). Bacillus sp. strain L81 and Arthrobacter oxidans strain BB1 performed best with a decrease in the disease index of 61.2 and 52.3%, respectively, and a reduction in the mortality due to salt stress of 72.4 and 57.8%, respectively. Additionally, significant differences were found in growth and photosynthesis, again, L81 and BB1 performed best either in normal or under stress conditions. In order to elucidate the pathway elicited by these two strains to induce systemic resistance, experiments with the transgenic line of Arabidopsis thaliana NahG (defective in salicylic acid [SA]) and with the jar1 mutant (defective in jasmonic acid) were carried out. Results showed that the SA-dependent pathway was involved in the defense response induced by strains L81 and BB1. Results from quantitative reverse transcription-polymerase chain reaction analysis of the PR1 gene, related to the SA-dependent pathway and the PDF1.2 gene related to the SA-independent pathway, showed an increased expression of PR1 in BB1-treated plants, confirming involvement of the SA-dependent pathway in the defensive response.


2016 ◽  
Vol 13 (2) ◽  
pp. 253-260
Author(s):  
Baghdad Science Journal

This study was conducted to evaluate the efficiency of some chemicals and biological agents to induce systemic resistance (ISR) against to wheat common bunt disease caused by the two species of fungus Tilletia tritici (Bjerk.) Wint (T. caries (Dac.) Tul.) and T. laevis Kuhn (T. foetida (Wall.) Liro. Trails in the efforts to find an alternative, safe and environmentally friendly means to control the disease. Results of this study which carried out during two consecutive seasons for the years 2012 - 2013 and 2013 - 2014 at two different environmental locations. Seed treatment by (SA 100 and 200 mg/L, 500 ?–aminobutyric acid (BABA) and 1000 mg/L, Effective Microorganisms (EM1) 40 and 150 ml/kg seeds) have led to high significant reduction in the percentage of common bunt compared with the control (plants resulting from the seeds contaminated non- treatment), While foliar treatment showed some significant differences, especially in the experiment carried out at the fields of College of Agriculture - Baghdad University compared with experiments carried out in the fields of Faculty of Agricultural Sciences -University of Sulaimania, which did not showed significant differences in most treatments. The treatment with Effective microorganisms was found efficient in reducing the infection rate compared with SA and BABA.


2018 ◽  
Vol 31 (3) ◽  
pp. 311-322 ◽  
Author(s):  
Shune Wang ◽  
Ying Zheng ◽  
Chun Gu ◽  
Chan He ◽  
Mengying Yang ◽  
...  

Bacillus cereus AR156 (AR156) is a plant growth–promoting rhizobacterium capable of inducing systemic resistance to Pseudomonas syringae pv. tomato in Arabidopsis thaliana. Here, we show that, when applied to Arabidopsis leaves, AR156 acted similarly to flg22, a typical pathogen-associated molecular pattern (PAMP), in initiating PAMP-triggered immunity (PTI). AR156-elicited PTI responses included phosphorylation of MPK3 and MPK6, induction of the expression of defense-related genes PR1, FRK1, WRKY22, and WRKY29, production of reactive oxygen species, and callose deposition. Pretreatment with AR156 still significantly reduced P. syringae pv. tomato multiplication and disease severity in NahG transgenic plants and mutants sid2-2, jar1, etr1, ein2, npr1, and fls2. This suggests that AR156-induced PTI responses require neither salicylic acid, jasmonic acid, and ethylene signaling nor flagella receptor kinase FLS2, the receptor of flg22. On the other hand, AR156 and flg22 acted in concert to differentially regulate a number of AGO1-bound microRNAs that function to mediate PTI. A full-genome transcriptional profiling analysis indicated that AR156 and flg22 activated similar transcriptional programs, coregulating the expression of 117 genes; their concerted regulation of 16 genes was confirmed by real-time quantitative polymerase chain reaction analysis. These results suggest that AR156 activates basal defense responses to P. syringae pv. tomato in Arabidopsis, similarly to flg22.


Microbiology ◽  
2012 ◽  
Vol 158 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Yariv Brotman ◽  
Jan Lisec ◽  
Michaël Méret ◽  
Ilan Chet ◽  
Lothar Willmitzer ◽  
...  

2012 ◽  
Vol 102 (4) ◽  
pp. 403-412 ◽  
Author(s):  
David M. Weller ◽  
Dmitri V. Mavrodi ◽  
Johan A. van Pelt ◽  
Corné M. J. Pieterse ◽  
Leendert C. van Loon ◽  
...  

Pseudomonas fluorescens strains that produce the polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) are among the most effective rhizobacteria that suppress root and crown rots, wilts, and damping-off diseases of a variety of crops, and they play a key role in the natural suppressiveness of some soils to certain soilborne pathogens. Root colonization by 2,4-DAPG-producing P. fluorescens strains Pf-5 (genotype A), Q2-87 (genotype B), Q8r1-96 (genotype D), and HT5-1 (genotype N) produced induced systemic resistance (ISR) in Arabidopsis thaliana accession Col-0 against bacterial speck caused by P. syringae pv. tomato. The ISR-eliciting activity of the four bacterial genotypes was similar, and all genotypes were equivalent in activity to the well-characterized strain P. fluorescens WCS417r. The 2,4-DAPG biosynthetic locus consists of the genes phlHGF and phlACBDE. phlD or phlBC mutants of Q2-87 (2,4-DAPG minus) were significantly reduced in ISR activity, and genetic complementation of the mutants restored ISR activity back to wild-type levels. A phlF regulatory mutant (overproducer of 2,4-DAPG) had ISR activity equivalent to the wild-type Q2-87. Introduction of DAPG into soil at concentrations of 10 to 250 μM 4 days before challenge inoculation induced resistance equivalent to or better than the bacteria. Strain Q2-87 induced resistance on transgenic NahG plants but not on npr1-1, jar1, and etr1 Arabidopsis mutants. These results indicate that the antibiotic 2,4-DAPG is a major determinant of ISR in 2,4-DAPG-producing P. fluorescens, that the genotype of the strain does not affect its ISR activity, and that the activity induced by these bacteria operates through the ethylene- and jasmonic acid-dependent signal transduction pathway.


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