scholarly journals Assessing Fitness Costs and Phenotypic Instability of Fentin Hydroxide and Tebuconazole Resistance in Venturia effusa

Plant Disease ◽  
2019 ◽  
Vol 103 (9) ◽  
pp. 2271-2276 ◽  
Author(s):  
Jeffrey R. Standish ◽  
Timothy B. Brenneman ◽  
Marin T. Brewer ◽  
Katherine L. Stevenson
Keyword(s):  
Oxidative Stress ◽  
Osmotic Stress ◽  
Conidial Germination ◽  
Fitness Cost ◽  
Fitness Costs ◽  
Fitness Components ◽  
Phenotypic Stability ◽  
Pecan Scab ◽  
Stability Of Resistance ◽  
Phenotypic Instability

Sensitivity monitoring of Venturia effusa, cause of pecan scab, has revealed insensitivity to fentin hydroxide and tebuconazole, but recent research indicates that the insensitivity to fentin hydroxide is not stable. A study was undertaken to determine if a fitness cost may be responsible for this instability. In this study, experiments were conducted to evaluate fitness components and phenotypic stability of insensitivity of V. effusa to fentin hydroxide and tebuconazole. Conidial production, conidial germination, microcolony growth, sensitivity to osmotic stress, and sensitivity to oxidative stress in the absence of fungicide were compared for isolates with differing sensitivities to both fungicides. Percent conidial germination decreased linearly with increasing fentin hydroxide insensitivity, and microcolony growth on 1.0 mM H2O2 decreased linearly with increasing tebuconazole insensitivity. Stability of resistance was assessed on concentrations of 1.0, 3.0, and 10 µg/ml of both fungicides prior to and after five transfers on non-fungicide-amended medium. Tebuconazole insensitivity was stable after transfers, but fentin hydroxide insensitivity on 1.0 and 3.0 µg/ml decreased significantly after transfers, indicating instability. Here we provide evidence that in V. effusa tebuconazole insensitivity is stable and fentin hydroxide insensitivity is not. These results suggest that fentin-hydroxide-resistant V. effusa isolates have reduced conidial viability compared with sensitive isolates, which may allow the population to regain sensitivity in the absence of this frequently used fungicide.

scholarly journals Fitness of Herbicide-Resistant Weeds: Current Knowledge and Implications for Management

Plants ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 469 ◽  
Author(s):  
Vila-Aiub
Keyword(s):  
Life History ◽  
Herbicide Resistance ◽  
Management Practices ◽  
Current Knowledge ◽  
Resistance Management ◽  
Fitness Cost ◽  
Plant Fitness ◽  
Resistance Mutations ◽  
Fitness Costs ◽  
Wide Range

Herbicide resistance is the ultimate evidence of the extraordinary capacity of weeds to evolve under stressful conditions. Despite the extraordinary plant fitness advantage endowed by herbicide resistance mutations in agroecosystems under herbicide selection, resistance mutations are predicted to exhibit an adaptation cost (i.e., fitness cost), relative to the susceptible wild-type, in herbicide untreated conditions. Fitness costs associated with herbicide resistance mutations are not universal and their expression depends on the particular mutation, genetic background, dominance of the fitness cost, and environmental conditions. The detrimental effects of herbicide resistance mutations on plant fitness may arise as a direct impact on fitness-related traits and/or coevolution with changes in other life history traits that ultimately may lead to fitness costs under particular ecological conditions. This brings the idea that a “lower adaptive value” of herbicide resistance mutations represents an opportunity for the design of resistance management practices that could minimize the evolution of herbicide resistance. It is evident that the challenge for weed management practices aiming to control, minimize, or even reverse the frequency of resistance mutations in the agricultural landscape is to “create” those agroecological conditions that could expose, exploit, and exacerbate those life history and/or fitness traits affecting the evolution of herbicide resistance mutations. Ideally, resistance management should implement a wide range of cultural practices leading to environmentally mediated fitness costs associated with herbicide resistance mutations.

scholarly journals Fitness Costs of Chlorantraniliprole Resistance Related to the SeNPF Overexpression in the Spodoptera exigua (Lepidoptera: Noctuidae)

2021 ◽  
Vol 22 (9) ◽  
pp. 5027
Author(s):  
Changwei Gong ◽  
Xinge Yao ◽  
Qunfang Yang ◽  
Xuegui Wang ◽  
Yuming Zhang ◽  
...  
Keyword(s):  
Insect Pest ◽  
Ryanodine Receptors ◽  
Oviposition Rate ◽  
Fitness Cost ◽  
Fitness Costs ◽  
Male Adult ◽  
Mating Response ◽  
Transmembrane Segments ◽  
High Level ◽  
Lepidoptera Noctuidae

Spodopteraexigua, a multifeeding insect pest, has developed a high level of resistance to chlorantraniliprole, which is a benzoylurea insecticide that targets the ryanodine receptors (RyRs). Herein, the resistant strain (SE-Sel) and sensitive strain (SE-Sus) were obtained by bidirectional screening for six generations. The potential oviposited eggs and oviposition rate of the SE-Sel strain were dramatically lower than those of the SE-Sus strain; on the contrary, the weights of prepupae and preadult were significantly increased. As a post-mating response, the higher number of non-oviposited eggs in the SE-Sel strain was caused by a lower mating rate. In addition, the expression levels of vitellogenin (SeVg) and its receptor (SeVgR) in the SE-Sel strain were consistently lower than those in the SE-Sus strain. An RyRI4743M mutation, contributing to the resistance to chlorantraniliprole, was located in the S3 transmembrane segments and might have affected the release of calcium ions; it led to the upregulated expression of the neuropeptide SeNPF and its receptor SeNPFR, and the mating and oviposition rate were significantly recovered when the SeNPF was knocked down though RNA interference (RNAi) in the male adult of the SE-Sel strain. Moreover, the expression of the juvenile hormone-binding proteins SeJHBWDS3 and SeJHBAN in the male adult of the SE-Sel strain was significantly decreased, which proved the existence of a fitness cost from another angle. Therefore, these results indicate that the fitness cost accompanied by chlorantraniliprole resistance in S. exigua may be related to the decrease in mating desire due to SeNPF overexpression.

Nitro‐oxidative stress induces the formation of roots' cortical aerenchyma in rice under osmotic stress

2021 ◽  
Author(s):  
Sahana Basu ◽  
Surbhi Kumari ◽  
Alok Kumar ◽  
Rimsha Shahid ◽  
Santosh Kumar ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Osmotic Stress

scholarly journals Root System Architecture Plasticity of Bread Wheat in Response to Oxidative Burst under Extended Osmotic Stress

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 939
Author(s):  
Omar Azab ◽  
Abdullah Al-Doss ◽  
Thobayet Alshahrani ◽  
Salah El-Hendawy ◽  
Adel M. Zakri ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Membrane Potential ◽  
Osmotic Stress ◽  
Root System ◽  
Bread Wheat ◽  
System Architecture ◽  
Mitochondrial Membrane ◽  
Root System Architecture ◽  
Root Tips ◽  
Scavenging Capacity

There is a demand for an increase in crop production because of the growing population, but water shortage hinders the expansion of wheat cultivation, one of the most important crops worldwide. Polyethylene glycol (PEG) was used to mimic drought stress due to its high osmotic potentials generated in plants subjected to it. This study aimed to determine the root system architecture (RSA) plasticity of eight bread wheat genotypes under osmotic stress in relation to the oxidative status and mitochondrial membrane potential of their root tips. Osmotic stress application resulted in differences in the RSA between the eight genotypes, where genotypes were divided into adapted genotypes that have non-significant decreased values in lateral roots number (LRN) and total root length (TRL), while non-adapted genotypes have a significant decrease in LRN, TRL, root volume (RV), and root surface area (SA). Accumulation of intracellular ROS formation in root tips and elongation zone was observed in the non-adapted genotypes due to PEG-induced oxidative stress. Mitochondrial membrane potential (∆Ψm) was measured for both stress and non-stress treatments in the eight genotypes as a biomarker for programmed cell death as a result of induced osmotic stress, in correlation with RSA traits. PEG treatment increased scavenging capacity of the genotypes from 1.4-fold in the sensitive genotype Gemmiza 7 to 14.3-fold in the adapted genotype Sakha 94. The adapted genotypes showed greater root trait values, ∆Ψm plasticity correlated with high scavenging capacity, and less ROS accumulation in the root tissue, while the non-adapted genotypes showed little scavenging capacity in both treatments, accompanied by mitochondrial membrane permeability, suggesting mitochondrial dysfunction as a result of oxidative stress.

Age-dependent fitness costs of alarm signaling in aphids

2003 ◽  
Vol 81 (5) ◽  
pp. 757-762 ◽  
Author(s):  
Edward B Mondor ◽  
Bernard D Roitberg
Keyword(s):  
Alarm Pheromone ◽  
Fourth Instar ◽  
Fitness Cost ◽  
Fitness Costs ◽  
Alarm Signal ◽  
Offspring Production ◽  
Direct Fitness ◽  
Alarm Signaling ◽  
Pea Aphids ◽  
Age Dependent

For an alarm signal to evolve, the benefits to the signaler must outweigh the costs of sending the signal. Research has largely focused on the benefits of alarm signaling, and the costs to an organism of sending an alarm signal are not well known. When attacked by a predator, aphids secrete cornicle droplets, containing an alarm pheromone, for individual protection and to warn clonemates. As aphid alarm pheromone is synthesized de novo in a feedback loop with juvenile hormone, we hypothesized that the secretion of cornicle droplets may result in a direct fitness cost to the emitter. We show that the secretion of a single cornicle droplet by pre-reproductive (third- and fourth-instar) pea aphids, Acyrthosiphon pisum, directly altered the timing and number of offspring produced. Third-instar pea aphids delayed offspring production but produced more offspring overall than non-secreting aphids, demonstrating a life-history shift but no significant fitness cost of droplet secretion. Fourth-instar pea aphids also delayed offspring production but produced the same number of offspring as non-secretors, resulting in a direct fitness cost of droplet secretion. Offspring production by adult, reproductive pea aphids that secreted a cornicle droplet did not differ from that of non-secretors. Thus, the fitness costs of secreting cornicle droplets containing an alarm signal are age-dependent.

Apoptosis signal-regulating kinase 1 is crucial for oxidative stress-induced but not for osmotic stress-induced hepatocyte cell death

Life Sciences ◽  
2008 ◽  
Vol 83 (25-26) ◽  
pp. 859-864 ◽  
Author(s):  
Kenji Taki ◽  
Rieko Shimozono ◽  
Hajime Kusano ◽  
Nobutaka Suzuki ◽  
Katsuhiro Shinjo ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Osmotic Stress

scholarly journals Atypical meiosis can be adaptive in outcrossed S. pombe due to wtf meiotic drivers

2020 ◽  
Author(s):  
María Angélica Bravo Núñez ◽  
Ibrahim M. Sabbarini ◽  
Lauren E. Eide ◽  
Robert L. Unckless ◽  
Sarah E. Zanders
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Fitness Landscape ◽  
Fitness Cost ◽  
Fitness Costs ◽  
Diploid Gametes ◽  
Selection Of

AbstractKiller meiotic drivers are genetic parasites that destroy ‘sibling’ gametes lacking the driver allele. The fitness costs of drive can lead to selection of unlinked suppressors. This suppression could involve evolutionary tradeoffs that compromise gametogenesis and contribute to infertility. Schizosaccharomyces pombe, an organism containing numerous gamete-killing wtf drivers, offers a tractable system to test this hypothesis. Here, we demonstrate that in scenarios analogous to outcrossing, wtf drivers generate a fitness landscape in which atypical gametes, such as aneuploids and diploids, are advantageous. In this context, wtf drivers can decrease the fitness cost of mutations that disrupt meiotic fidelity and, in some circumstances, can even make such mutations beneficial. Moreover, we find that S. pombe isolates vary greatly in their ability to make haploid gametes, with some isolates generating more than 25% aneuploid or diploid gametes. This work empirically demonstrates the potential for meiotic drivers to shape the evolution of gametogenesis.

scholarly journals Oxidative stress and the presence of bacteria increase gene expression of the antimicrobial peptide aclasin, a fungal CSαβ defensin in Aspergillus clavatus

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6290 ◽  
Author(s):  
Gabriela Contreras ◽  
Nessa Wang ◽  
Holger Schäfer ◽  
Michael Wink
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Heat Shock ◽  
Osmotic Stress ◽  
Broad Class ◽  
Stress Conditions ◽  
Aspergillus Clavatus ◽  
Stress Oxidative ◽  
Fungal Defensin ◽  
Β Sheet

Background Antimicrobial peptides (AMPs) represent a broad class of naturally occurring antimicrobial compounds. Plants, invertebrates and fungi produce various AMPs as, for example, defensins. Most of these defensins are characterised by the presence of a cysteine-stabilised α-helical and β-sheet (CSαβ) motif. The changes in gene expression of a fungal CSαβ defensin by stress conditions were investigated in Aspergillus clavatus. A. clavatus produces the CSαβ defensin Aclasin, which is encoded by the aclasin gene. Methods Aclasin expression was evaluated in submerged mycelium cultures under heat shock, osmotic stress, oxidative stress and the presence of bacteria by quantitative real-time PCR. Results Aclasin expression increased two fold under oxidative stress conditions and in the presence of viable and heat-killed Bacillus megaterium. Under heat shock and osmotic stress, aclasin expression decreased. Discussion The results suggest that oxidative stress and the presence of bacteria might regulate fungal defensin expression. Moreover, fungi might recognise microorganisms as plants and animals do.

scholarly journals Role of Silicon in Mediating Salt Tolerance in Plants: A Review

Plants ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 147 ◽  
Author(s):  
Yong-Xing Zhu ◽  
Hai-Jun Gong ◽  
Jun-Liang Yin
Keyword(s):  
Oxidative Stress ◽  
Salt Stress ◽  
Osmotic Stress ◽  
Stress Responses ◽  
Polyamine Metabolism ◽  
Research Areas ◽  
Aquaporin Gene ◽  
Ion Imbalance ◽  
The Impact

Salt stress is a major threat for plant growth worldwide. The regulatory mechanisms of silicon in alleviating salt stress have been widely studied using physiological, molecular genetics, and genomic approaches. Recently, progresses have been made in elucidating the alleviative effects of silicon in salt-induced osmotic stress, Na toxicity, and oxidative stress. In this review, we highlight recent development on the impact of silicon application on salt stress responses. Emphasis will be given to the following aspects. (1) Silicon transporters have been experimentally identified in different plant species and their structure feature could be an important molecular basis for silicon permeability. (2) Silicon could mediate salt-induced ion imbalance by (i) regulating Na+ uptake, transport, and distribution and (ii) regulating polyamine levels. (3) Si-mediated upregulation of aquaporin gene expression and osmotic adjustment play important roles in alleviating salinity-induced osmotic stress. (4) Silicon application direct/indirectly mitigates oxidative stress via regulating the antioxidant defense and polyamine metabolism. (5) Omics studies reveal that silicon could regulate plants’ response to salt stress by modulating the expression of various genes including transcription factors and hormone-related genes. Finally, research areas that require further investigation to provide a deeper understanding of the role of silicon in plants are highlighted.

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