Phenotyping dauer juvenile oxidative stress tolerance, longevity and persistence within wild type and inbred lines of the entomopathogenic nematode Heterorhabditis bacteriophora

The commercial use of the entomopathogenic nematodeHeterorhabditis bacteriophoraas a biocontrol agent against noxious insects is limited due to its relatively short shelf-life. Longevity of dauer juveniles (DJ) during storage and in transit to end users is considerably restricted by environmental stresses. As a derivative stress triggered by environmental factors, oxidative stress causes a strong internal metabolic imbalance leading to lifespan reduction. In this study, the relation between DJ oxidative stress tolerance and longevity inH. bacteriophorawas investigated at 25 and 7°C. A strong and significant correlation between DJ oxidative stress tolerance and longevity during storage in Ringer’s solution ( at 7°C; at 25°C) was recorded. Phenotyping of these traits was performed for 40H. bacteriophorawild type strain and inbred line collections. At 25°C, the mean time survived in Ringer’s by 50% of the DJ (MTS50) ranged from 21 to 57 days, whereas under oxidative stress, survival was from 3 to 22 days. At 7°C, a maximum MTS50of 94 days was assessed when DJ were stored in Ringer’s, while the maximum MTS50was only 25 days with oxidative stress induction. The heritability of DJ tolerance to oxidative stress, determined by using homozygous inbred lines, is high (), an indication of a high probability for successful selective breeding. In a subset of preselectedH. bacteriophorainbred lines, DJ oxidative stress tolerance correlated with the DJ survival (persistence) after application to sand (). The study provides fundamental data required for a genetic breeding programme to produce hybrids with improved stress tolerance and prolonged shelf-life and soil persistence.

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Gene expression analysis of oxidative stress tolerance in the entomopathogenic nematode Heterorhabditis bacteriophora

Nematology ◽

10.1163/15685411-bja10025 ◽

2020 ◽

Vol 23 (1) ◽

pp. 15-31

Author(s):

Nanette Hope Sumaya ◽

Olaniyi Olarewaju ◽

Gebermedihin Ambaw ◽

Abdi Yali ◽

Giulia Godina ◽

...

Keyword(s):

Oxidative Stress ◽

Stress Tolerance ◽

Entomopathogenic Nematode ◽

Transcriptome Assembly ◽

Heterorhabditis Bacteriophora ◽

Biological Processes ◽

Term Survival ◽

Oxidative Stress Tolerance ◽

Tolerant Line ◽

Sensitive Line

Summary The entomopathogenic nematode (EPN) Heterorhabditis bacteriophora is used as a biological control agent against diverse insect pests. Nematode-based products contain third-stage Dauer juveniles (DJ), which are adapted to long-term survival. Their longevity can be limited by stress conditions during industrial production up to field application. Oxidative stress has been recently reported to have a direct influence on the H. bacteriophora DJ longevity. Thus, understanding mechanisms by which DJ respond to oxidative stress can provide insights to improve DJ longevity. In this study, we carried out a comparative transcriptomic analysis on the early stage of oxidative stress induction (4 h) in two H. bacteriophora inbred lines with contrasting oxidative stress tolerance, HU2-IL1 (stress-tolerant) and PT1-IL1 (stress-sensitive). For assessing the transcriptome, MACE, a versatile RNA-seq variant was applied. Our de novo transcriptome assembly generated more than 20 000 transcripts, from which 10 290 were linked to 9776 different Uniprot accessions. The majority of the annotated transcripts presented high homology to parasitic nematodes within the genus Ancylostoma, whereas homology to the genus Caenorhabditis was negligible. A total of 630 and 461 transcripts were up-regulated (log2 fold-change (FC) ⩾ 2.0) in the stress-sensitive and the stress-tolerant line, respectively. The proportion of down-regulated transcripts was higher for both lines. However, down-regulation in the stress-sensitive line (5207 transcripts) exhibited a larger proportion than in the tolerant line (1844 transcripts), which indicates that targeted suppression of biological processes is also a crucial factor for the survival of H. bacteriophora under oxidative stress. Our global view of the transcriptome remodelling under oxidative stress suggests that the stress-sensitive line fails to maintain vital biological processes in contrast to the tolerant line. Interestingly, both lines activated similar biological processes directly involved in detoxification of reactive oxygen species, indicating that expression changes on transcript isoforms are of high relevance in this context. This study will open ways for the selection of DJ longevity predictor genes and allow the design of molecular markers for the breeding of improved lines.

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Applying inbreeding, hybridization and mutagenesis to improve oxidative stress tolerance and longevity of the entomopathogenic nematode Heterorhabditis bacteriophora

Journal of Invertebrate Pathology ◽

10.1016/j.jip.2017.11.001 ◽

2018 ◽

Vol 151 ◽

pp. 50-58 ◽

Cited By ~ 3

Author(s):

Nanette Hope Sumaya ◽

Riddhi Gohil ◽

Christopher Okolo ◽

Temesgen Addis ◽

Verena Doerfler ◽

...

Keyword(s):

Oxidative Stress ◽

Stress Tolerance ◽

Entomopathogenic Nematode ◽

Heterorhabditis Bacteriophora ◽

Oxidative Stress Tolerance

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Isolation and characterization of an atypical LEA gene (IpLEA) from Ipomoea pes-caprae conferring salt/drought and oxidative stress tolerance

Scientific Reports ◽

10.1038/s41598-019-50813-w ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Jiexuan Zheng ◽

Huaxiang Su ◽

Ruoyi Lin ◽

Hui Zhang ◽

Kuaifei Xia ◽

...

Keyword(s):

Oxidative Stress ◽

Stress Tolerance ◽

Abiotic Stresses ◽

Expression Patterns ◽

Large Family ◽

Regulatory Elements ◽

Pcr Analysis ◽

Wild Type ◽

Oxidative Stress Tolerance ◽

Isolation And Characterization

Abstract Late embryogenesis abundant (LEA) proteins belong to a large family that exists widely in plants and is mainly involved in desiccation processes during plant development or in the response to abiotic stresses. Here, we reported on an atypical LEA gene (IpLEA) related to salt tolerance from Ipomoea pes-caprae L. (Convolvulaceae). Sequence analysis revealed that IpLEA belongs to the LEA_2 (PF03168) group. IpLEA was shown to have a cytoplasmic localization pattern. Quantitative reverse transcription PCR analysis showed that IpLEA was widely expressed in different organs of the I. pes-caprae plants, and the expression levels increased following salt, osmotic, oxidative, freezing, and abscisic acid treatments. Analysis of the 1,495 bp promoter of IpLEA identified distinct cis-acting regulatory elements involved in abiotic stress. Induction of IpLEA improved Escherichia coli growth performance compared with the control under abiotic stresses. To further assess the function of IpLEA in plants, transgenic Arabidopsis plants overexpressing IpLEA were generated. The IpLEA-overexpressing Arabidopsis seedlings and adult plants showed higher tolerance to salt and drought stress than the wild-type. The transgenic plants also showed higher oxidative stress tolerance than the wild-type Arabidopsis. Furthermore, the expression patterns of a series of stress-responsive genes were affected. The results indicate that IpLEA is involved in the plant response to salt and drought, probably by mediating water homeostasis or by acting as a reactive oxygen species scavenger, thereby influencing physiological processes under various abiotic stresses in microorganisms and plants.

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The Streptococcus mutans vicX Gene Product Modulates gtfB/C Expression, Biofilm Formation, Genetic Competence, and Oxidative Stress Tolerance

Journal of Bacteriology ◽

10.1128/jb.01161-06 ◽

2006 ◽

Vol 189 (4) ◽

pp. 1451-1458 ◽

Cited By ~ 62

Author(s):

M. Dilani Senadheera ◽

Andrew W. C. Lee ◽

David C. I. Hung ◽

Grace A. Spatafora ◽

Steven D. Goodman ◽

...

Keyword(s):

Oxidative Stress ◽

Stress Tolerance ◽

Gene Product ◽

Streptococcus Mutans ◽

Parent Strain ◽

Adhesion Assay ◽

Wild Type ◽

Coding Region ◽

Oxidative Stress Tolerance ◽

Cell Clusters

ABSTRACT Streptococcus mutans is considered one of the primary etiologic agents of dental caries. Previously, we characterized the VicRK two-component signal transduction system, which regulates multiple virulence factors of S. mutans. In this study, we focused on the vicX gene of the vicRKX tricistronic operon. To characterize vicX, we constructed a nonpolar deletion mutation in the vicX coding region in S. mutans UA159. The growth kinetics of the mutant (designated SmuvicX) showed that the doubling time was longer and that there was considerable sensitivity to paraquat-induced oxidative stress. Supplementing a culture of the wild-type UA159 strain with paraquat significantly increased the expression of vicX (P < 0.05, as determined by analysis of variance [ANOVA]), confirming the role of this gene in oxidative stress tolerance in S. mutans. Examination of mutant biofilms revealed architecturally altered cell clusters that were seemingly denser than the wild-type cell clusters. Interestingly, vicX-deficient cells grown in a glucose-supplemented medium exhibited significantly increased glucosyltransferase B/C (gtfB/C) expression compared with the expression in the wild type (P < 0.05, as determined by ANOVA). Moreover, a sucrose-dependent adhesion assay performed using an S. mutans GS5-derived vicX null mutant demonstrated that the adhesiveness of this mutant was enhanced compared with that of the parent strain and isogenic mutants of the parent strain lacking gtfB and/or gtfC. Also, disruption of vicX reduced the genetic transformability of the mutant approximately 10-fold compared with that of the parent strain (P < 0.05, as determined by ANOVA). Collectively, these findings provide insight into important phenotypes controlled by the vicX gene product that can impact S. mutans pathogenicity.

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