scholarly journals Tomato Divinyl Ether-Biosynthesis Pathway Is Implicated in Modulating of Root-Knot Nematode Meloidogyne javanica's Parasitic Ability

2021 ◽  
Vol 12 ◽  
Author(s):  
Payal Sanadhya ◽  
Anil Kumar ◽  
Patricia Bucki ◽  
Nathalia Fitoussi ◽  
Mira Carmeli-Weissberg ◽  
...  
Keyword(s):  
Methyl Salicylate ◽  
Nematode Infection ◽  
Divinyl Ether ◽  
Fourth Stage ◽  
Root Knot Nematode ◽  
Signal Molecule ◽  
Transgenic Yeast ◽  
Spatiotemporal Expression ◽  
Solanaceous Plants

The role of the 9-lipoxygenase (9-LOX)-derived oxylipins in plant defense is mainly known in solanaceous plants. In this work, we identify the functional role of the tomato divinyl ether synthase (LeDES) branch, which exclusively converts 9-hydroperoxides to the 9-divinyl ethers (DVEs) colneleic acid (CA) and colnelenic acid (CnA), during infection by the root-knot nematode Meloidogyne javanica. Analysis of LeDES expression in roots indicated a concurrent response to nematode infection, demonstrating a sharp increase in expression during the molting of third/fourth-stage juveniles, 15 days after inoculation. Spatiotemporal expression analysis using an LeDES promoter:GUS tomato line showed high GUS activity associated with the developing gall; however the GUS signal became more constricted as infection progressed to the mature nematode feeding sites, and eventually disappeared. Wounding did not activate the LeDES promoter, but auxins and methyl salicylate triggered LeDES expression, indicating a hormone-mediated function of DVEs. Heterologous expression of LeDES in Arabidopsis thaliana rendered the plants more resistant to nematode infection and resulted in a significant reduction in third/fourth-stage juveniles and adult females as compared to a vector control and the wild type. To further evaluate the nematotoxic activity of the DVEs CA and CnA, recombinant yeast that catalyzes the formation of CA and CnA from 9-hydroperoxides was generated. Transgenic yeast accumulating CnA was tested for its impact on M. javanica juveniles, indicating a decrease in second-stage juvenile motility. Taken together, our results suggest an important role for LeDES as a determinant in the defense response during M. javanica parasitism, and indicate two functional modes: directly via DVE motility inhibition effect and through signal molecule-mediated defense reactions to nematodes that depend on methyl salicylate.

Contribution of Root-Knot Nematodes to Aflatoxin Contamination in Peanut (Arachis hypogaea)

2013 ◽  
Vol 40 (1) ◽  
pp. 31-39 ◽  
Author(s):  
P. Timper ◽  
D. M. Wilson ◽  
C. C. Holbrook
Keyword(s):  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Nematode Infection ◽  
Peanut Kernel ◽  
Root Infection ◽  
Root Knot Nematode ◽  
Water Control ◽  
Rainout Shelter ◽  
One Year

ABSTRACT Peanut kernels are susceptible to colonization by some species of Aspergillus which, under conditions of drought and high temperatures, can produce aflatoxins prior to harvest. The objective of this research was to determine the mechanism by which the peanut root-knot nematode (Meloidogyne arenaria) increases aflatoxin contamination in peanut. Research determined 1) the role of nematode infection of roots vs. pods in increased aflatoxin contamination and 2) whether increased aflatoxin production in nematode-infected peanut is due to a greater percentage of small or immature kernels. An additional objective was to determine whether a peanut cultivar with resistance to M. arenaria would reduce the risk of preharvest aflatoxin contamination. In the greenhouse, researchers physically separated root growth from pod set and inoculated each location with M. arenaria or a water control in a 2 × 2 factorial design with 12–15 replications. Of the six trials conducted, data indicated that pod and root infection by M. arenaria was associated with elevated aflatoxin concentrations in one and three trials, respectively. This suggests that root infection by the nematode can increase aflatoxin concentrations in the peanut kernel. Another 2 × 2 factorial experiment was conducted with two peanut genotypes (Tifguard and TifGP-2) and two nematode treatments (with and without M. arenaria) with six replications. The cultivar Tifguard is resistant to M. arenaria and TifGP-2 is susceptible. The experiment was carried out in 24 field microplots equipped with a rainout shelter. The experiment was conducted five times from 2006 to 2010. Infection of TifGP-2 by M. arenaria did not lead to greater percentages of small kernels. In only one year (2007), nematodes appeared to increase the percentage of damaged kernels, though aflatoxin concentrations were not affected by nematodes in that year. In the rainout shelter experiment, 2006 was the only year where nematode infection of peanut increased aflatoxin concentrations. In that year, there were lower aflatoxin concentrations in the nematode-resistant cultivar Tifguard than the susceptible germplasm TifGP-2 (12 vs. 136 ng/g).

Role of stat6 in hypercontractility of murine small intestinal smooth muscle induced by nematode infection

2001 ◽  
Vol 120 (5) ◽  
pp. A534-A534
Author(s):  
A ZHAO ◽  
D MULLOY ◽  
J URBANJR ◽  
W GAUSE ◽  
T SHEADONOHUE
Keyword(s):  
Smooth Muscle ◽  
Nematode Infection ◽  
Intestinal Smooth Muscle ◽  
Small Intestinal

The suppression of tomato defence response genes upon potato cyst nematode infection indicates a key regulatory role of miRNAs

2017 ◽  
Vol 113 ◽  
pp. 51-55 ◽  
Author(s):  
Magdalena Święcicka ◽  
Waldemar Skowron ◽  
Piotr Cieszyński ◽  
Joanna Dąbrowska-Bronk ◽  
Mateusz Matuszkiewicz ◽  
...  
Keyword(s):  
Cyst Nematode ◽  
Defence Response ◽  
Nematode Infection ◽  
Potato Cyst Nematode ◽  
Regulatory Role

scholarly journals Indole Acts as an Extracellular Cue Regulating Gene Expression in Vibrio cholerae

2009 ◽  
Vol 191 (11) ◽  
pp. 3504-3516 ◽  
Author(s):  
Ryan S. Mueller ◽  
Sinem Beyhan ◽  
Simran G. Saini ◽  
Fitnat H. Yildiz ◽  
Douglas H. Bartlett
Keyword(s):  
Gene Expression ◽  
Vibrio Cholerae ◽  
Biofilm Formation ◽  
Signal Molecule ◽  
Control Of Gene Expression ◽  
Protozoan Grazing ◽  
Extracellular Signal ◽  
Grazing Resistance ◽  
Indole Signaling

ABSTRACT Indole has been proposed to act as an extracellular signal molecule influencing biofilm formation in a range of bacteria. For this study, the role of indole in Vibrio cholerae biofilm formation was examined. It was shown that indole activates genes involved in vibrio polysaccharide (VPS) production, which is essential for V. cholerae biofilm formation. In addition to activating these genes, it was determined using microarrays that indole influences the expression of many other genes, including those involved in motility, protozoan grazing resistance, iron utilization, and ion transport. A transposon mutagenesis screen revealed additional components of the indole-VPS regulatory circuitry. The indole signaling cascade includes the DksA protein along with known regulators of VPS production, VpsR and CdgA. A working model is presented in which global control of gene expression by indole is coordinated through σ54 and associated transcriptional regulators.

scholarly journals Rhizosphere Microbiomes from Root Knot Nematode Non-infested Plants Suppress Nematode Infection

2019 ◽  
Vol 78 (2) ◽  
pp. 470-481 ◽  
Author(s):  
Dongmei Zhou ◽  
Hui Feng ◽  
Taruna Schuelke ◽  
Alejandro De Santiago ◽  
Qimeng Zhang ◽  
...  
Keyword(s):  
Nematode Infection ◽  
Root Knot Nematode

scholarly journals Transcriptomic analysis of resistant and susceptible responses in a new model root-knot nematode infection system using Solanum torvum and Meloidogyne arenaria

2021 ◽  
Author(s):  
Kazuki Sato ◽  
Taketo Uehara ◽  
Julia Holbein ◽  
Yuko Sasaki-Sekimoto ◽  
Pamela Gan ◽  
...  
Keyword(s):  
Nematode Infection ◽  
Plant Genome ◽  
Root Tip ◽  
Post Inoculation ◽  
Sequencing Analysis ◽  
Class Iii ◽  
Root Knot Nematode ◽  
Cell Wall Modification ◽  
Solanum Torvum

ABSTRACTRoot-knot nematodes (RKNs) are among the most devastating pests in agriculture. Solanum torvum Sw. (turkey berry) has been used as a rootstock for eggplant (aubergine) cultivation because of its resistance to RKNs, including Meloidogyne incognita and M. arenaria. We previously found that a pathotype of M. arenaria, A2-J, is able to infect and propagate in S. torvum. In vitro infection assays showed that S. torvum induces the accumulation of brown pigments during avirulent pathotype A2-O infection, but not during virulent A2-J infection. This experimental system is advantageous because resistant and susceptible responses can be distinguished within a few days, and because a single plant genome can yield information about both resistant and susceptible responses. Comparative RNA-sequencing analysis of S. torvum inoculated with A2-J and A2-O at early stages of infection was used to parse the specific resistance and susceptible responses. Infection with A2-J did not induce statistically significant changes in gene expression within one day post-inoculation (DPI), but afterward, A2-J specifically induced the expression of chalcone synthase, spermidine synthase, and genes related to cell wall modification and transmembrane transport. Infection with A2-O rapidly induced the expression of genes encoding class III peroxidases, sesquiterpene synthases, and fatty acid desaturases at 1 DPI, followed by genes involved in defense, hormone signaling, and the biosynthesis of lignin at 3 DPI. Both isolates induced the expression of suberin biosynthetic genes, which may be triggered by wounding during nematode infection. Histochemical analysis revealed that A2-O, but not A2-J, induced lignin accumulation at the root tip, suggesting that physical reinforcement of cell walls with lignin is an important defense response against nematodes. The S. torvum-RKN system can provide a molecular basis for understanding plant-nematode interactions.

Norm internalisation revisited: Norm contestation and the life of norms at the extreme of the norm cascade

2019 ◽  
Vol 9 (1) ◽  
pp. 76-116 ◽  
Author(s):  
LUCRECIA GARCÍA IOMMI
Keyword(s):  
Social Recognition ◽  
Life Cycle Model ◽  
Fourth Stage ◽  
Cycle Model ◽  
Formal Validity ◽  
Heuristic Device ◽  
Norm Change ◽  
Cultural Validation ◽  
Point Of Reference

Abstract:Finnemore and Sikkink’s norms life cycle model (NLCM) is a powerful heuristic device that continues to be a mandatory point of reference for theoretical and empirical scholarship on norm change. Yet the internalisation stage as conceptualised in the NLCM is problematic. Drawing from Wiener’s Theory of Contestation, this article proposes to reconceptualise the norm internalisation stage as the phase at the extreme of the norm cascade in which inherently contested norms simultaneously enjoy formal validity, social recognition, and cultural validation among stakeholders. Unlike Finnemore and Sikkink’s, this conceptualisation focuses solely on norm validity and does not assume ‘almost automatic’ compliance. While Finnemore and Sikkink emphasise habit and institutionalisation as mechanisms of internalisation, the proposed conceptualisation highlights the role of applicatory contestation under conditions of high contestedness. Furthermore, I argue that internalised norms continue to be contested. Finally, my conceptualisation explicitly incorporates norm regression as the fourth stage of the NLCM. Norms might regress because they become obsolete, they change, or they are replaced. To assess the descriptive power of the proposed conceptualisation vis-à-vis Finnemore and Sikkink’s, the article applies them to the analysis of the norm that prohibits torture.

Sign in / Sign up

Export Citation Format

Share Document