Mitigation of Environmental Stress-Impacts in Plants: Role of Sole and Combinatory Exogenous Application of Glutathione

Glutathione (GSH; γ-glutamyl-cysteinyl-glycine), a low-molecular-weight thiol, is the most pivotal metabolite involved in the antioxidative defense system of plants. The modulation of GSH on the plant in response to environmental stresses could be illustrated through key pathways such as reactive oxygen species (ROS) scavenging and signaling, methylglyoxal (MG) detoxification and signaling, upregulation of gene expression for antioxidant enzymes, and metal chelation and xenobiotic detoxification. However, under extreme stresses, the biosynthesis of GSH may get inhibited, causing an excess accumulation of ROS that induces oxidative damage on plants. Hence, this gives rise to the idea of exploring the use of exogenous GSH in mitigating various abiotic stresses. Extensive studies conducted borne positive results in plant growth with the integration of exogenous GSH. The same is being observed in terms of crop yield index and correlated intrinsic properties. Though, the improvement in plant growth and yield contributed by exogenous GSH is limited and subjected to the glutathione pool [GSH/GSSG; the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG)] homeostasis. Therefore, recent studies focused on the sequenced application of GSH was performed in order to complement the existing limitation. Along with various innovative approaches in combinatory use with different bioactive compounds (proline, citric acid, ascorbic acid, melatonin), biostimulants (putrescine, Moringa leaf extract, selenium, humic acid), and microorganisms (cyanobacteria) have resulted in significant improvements when compared to the individual application of GSH. In this review, we reinforced our understanding of biosynthesis, metabolism and consolidated different roles of exogenous GSH in response to environmental stresses. Strategy was also taken by focusing on the recent progress of research in this niche area by covering on its individualized and combinatory applications of GSH prominently in response to the abiotic stresses. In short, the review provides a holistic overview of GSH and may shed light on future studies and its uses.

Transcriptional responses of Daphnis nerii larval midgut to oral infection by Daphnis nerii cypovirus-23

Background Daphnis nerii cypovirus-23 (DnCPV-23) is a new type of cypovirus and has a lethal effect on the oleander hawk moth, Daphnis nerii which feeds on leave of Oleander and Catharanthus et al. After DnCPV-23 infection, the change of Daphnis nerii responses has not been reported. Methods To better understand the pathogenic mechanism of DnCPV-23 infection, 3rd-instar Daphnis nerii larvae were orally infected with DnCPV-23 occlusion bodies and the transcriptional responses of the Daphnis nerii midgut were analyzed 72 h post-infection using RNA-seq. Results The results showed that 1979 differentially expressed Daphnis nerii transcripts in the infected midgut had been identified. KEGG analysis showed that protein digestion and absorption, Toll and Imd signaling pathway were down-regulated. Based on the result, we speculated that food digestion and absorption in insect midgut might be impaired after virus infection. In addition, the down-regulation of the immune response may make D. nerii more susceptible to bacterial infections. Glycerophospholipid metabolism and xenobiotics metabolism were up-regulated. These two types of pathways may affect the viral replication and xenobiotic detoxification of insect, respectively. Conclusion These results may facilitate a better understanding of the changes in Daphnis nerii metabolism during cypovirus infection and serve as a basis for future research on the molecular mechanism of DnCPV-23 invasion.

Therapeutic Artemether-Lumefantrine Modulated Monosodium Glutamate-Related Adversity on Rats’ Kidney Histology and Antioxidant Response Bio-Indicators

Co-intake-related interactive-synergistic influence of artemether-lumefantrine, AL and monosodium glutamate, MSG that separately mediated oxidative stress could be significant on the kidney actively involved in xenobiotic detoxification and elimination. Thus, influence of AL on rats’ kidney histomorphology and antioxidant bio-indicators following MSG-challenge was assessed. For 7 days, thirty rats (n = 5) were respectively exposed to vehicle (distilled water), therapeutic AL (TAL), high AL (HAL), MSG, MSG plus TAL or MSG plus HAL. Significant (P<0.05) results comparison showed highest and least (P<0.05) albumin concentration (Mg/dl) in TAL-fed (3.76±0.33) and MSG-fed (1.88±0.70), rats. Total protein concentration (Mg/dl) in MSG-fed (4.04±2.04) and HAL-fed (4.76±1.92), rats lowered markedly. Highest glutathione peroxidase activity (IU/L) in TAL-fed (30.74±12.46) lowered in MSG plus HAL-fed (20.11±6.08) and MSG-fed (20.33±4.85), rats. Catalase activity (IU/L) in control was highest (4.89 ± 0.26) but least (2.58 ± 1.06) in MSG-fed rats. Zinc and Magnesium concentration (Mg/dl) was respectively highest (58.99±5.10) and least (3.48±0.31) in MSG plus HAL-fed but least (18.80±7.77) and highest (4.38±1.67) in MSG-fed, rats. Malondialdehyde concentration (µmol/ml) in MSG plus HAL-fed rats (4.04±0.67) was highest (P<0.05) and least (P<0.05) in HAL-fed rats (1.18±0.11). Differences in superoxide dismutase activity (IU/L) were, however, non-significant (P>0.05).Rats’ kidney photomicrographs (H&E × 400) revealed normal histo-architecture in control but varied degree of fibroplasias (TAL- ,HAL- and MSG plus TAL-fed) and necrosis with infiltrations (MSG plus HAL-and MSG-fed), rats. These demonstrated MSG-related adversity and significant modulation response of TAL, unlike HAL, on the rats’ kidney histology and studied antioxidant response bio-indicators.

NHR-8 and P-glycoproteins uncouple xenobiotic resistance from longevity in chemosensory C. elegans mutants

Longevity is often associated with stress resistance, but whether they are causally linked is incompletely understood. Here we investigate chemosensory-defective Caenorhabditis elegans mutants that are long-lived and stress resistant. We find that mutants in the intraflagellar transport protein gene osm-3 were significantly protected from tunicamycin-induced ER stress. While osm-3 lifespan extension is dependent on the key longevity factor DAF-16/FOXO, tunicamycin resistance was not. osm-3 mutants are protected from bacterial pathogens, which is pmk-1 p38 MAP kinase dependent, while TM resistance was pmk-1 independent. Expression of P-glycoprotein (PGP) xenobiotic detoxification genes was elevated in osm-3 mutants and their knockdown or inhibition with verapamil suppressed tunicamycin resistance. The nuclear hormone receptor nhr-8 was necessary to regulate a subset of PGPs. We thus identify a cell-nonautonomous regulation of xenobiotic detoxification and show that separate pathways are engaged to mediate longevity, pathogen resistance, and xenobiotic detoxification in osm-3 mutants.

Evidence for the Role of CYP51A and Xenobiotic Detoxification in Differential Sensitivity to Azole Fungicides in Boxwood Blight Pathogens

Boxwood blight, a fungal disease of ornamental plants (Buxus spp.), is caused by two sister species, Calonectria pseudonaviculata (Cps) and C. henricotiae (Che). Compared to Cps, Che is documented to display reduced sensitivity to fungicides, including the azole class of antifungals, which block synthesis of a key fungal membrane component, ergosterol. A previous study reported an ergosterol biosynthesis gene in Cps, CYP51A, to be a pseudogene, and RNA-Seq data confirm that a functional CYP51A is expressed only in Che. The lack of additional ergosterol biosynthesis genes showing significant differential expression suggests that the functional CYP51A in Che could contribute to reduced azole sensitivity when compared to Cps. RNA-Seq and bioinformatic analyses found that following azole treatment, 55 genes in Cps, belonging to diverse pathways, displayed a significant decrease in expression. Putative xenobiotic detoxification genes overexpressed in tetraconazole-treated Che encoded predicted monooxygenase and oxidoreductase enzymes. In summary, expression of a functional CYP51A gene and overexpression of predicted xenobiotic detoxification genes appear likely to contribute to differential fungicide sensitivity in these two sister taxa.

Transcriptional Responses of Daphnis nerii Larval Midgut to Oral Infection by 2 Daphnis nerii cypovirus-23

Background: Daphnis nerii cypovirus-23 (DnCPV-23) is a new type of cypovirus and has lethal effect on the oleander hawk moth, Daphnis nerii , which feeds on leave of Oleander and Catharanthus et al. After DnCPV-23 infection, the change of Daphnis nerii responses has not been reported.Methods: In order to better understand the pathogenic mechanism of DnCPV-23 infection, 3rdinstar Daphnis nerii larvae were orally infected with DnCPV-23 occlusion bodies and the transcriptional responses of the Daphnis nerii midgut were analyzed 72 h post-infection using RNA-seq.Results: The results showed that 1,979 differentially expressed Daphnis nerii transcripts in the infected midgut had been identified. KEGG analysis showed that protein digestion and absorption, Toll and Imd signaling pathway were down-regulated. Based on the result, it was possible the function of food digestion and absorption in insect midgut was impaired after virus infection. In addition, the down-regulation of the immune response may be conducive to viral immune escape. Glycerophospholipid metabolism and xenobiotics metabolism were up-regulated. These two types of pathways may affect the viral replication and xenobiotic detoxification of insect, respectively. Conclusion: These results may facilitate a better understanding of the changes in Daphnis nerii metabolism during cypovirus infection and serve as a basis for future research on the molecular mechanism of DnCPV-23 invasion.

The Foraging Gene, a New Environmental Adaptation Player Involved in Xenobiotic Detoxification

Foraging is vital for animals, especially for food. In Drosophila melanogaster, this behavior is controlled by the foraging gene (for) which encodes a cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG). In wild populations of Drosophila, rover individuals that exhibit long foraging trails and sitter individuals that exhibit short ones coexist and are characterized by high and low levels of PKG activity, respectively. We, therefore, postulated that rover flies are more exposed to environmental stresses, including xenobiotics contamination, than sitter flies. We then tested whether these flies differed in their ability to cope with xenobiotics by exposing them to insecticides from different chemical families. We performed toxicological tests and measured the activity and expression levels of different classes of detoxification enzymes. We have shown that a link exists between the for gene and certain cytochrome P450-dependent activities and that the expression of the insecticide-metabolizing cytochrome P450 Cyp6a2 is controlled by the for gene. An unsuspected regulatory pathway of P450s expression involving the for gene in Drosophila is revealed and we demonstrate its involvement in adaptation to chemicals in the environment. This work can serve as a basis for reconsidering adaptation to xenobiotics in light of the behavior of species, including humans.

ANALYSIS OF XENOBIOTIC DETOXIFICATION AND DNA-REPAIR GENES IN POPULATIONS LIVING IN PESTICIDE CONTAMINATED AREAS

Проведена оценка риска влияния многолетней пестицидной загрязненности окружающей среды на генетический статус населения, проживающего в 5 населенных пунктах Талгарского района (пп. Кызылкайрат, Бескайнар, Бельбулак, Амангельды, Енбекши) Алматинской области, где располагаются неутилизированные, запрещенные к использованию пестициды класса СОЗ. Результаты цитогенетического анализа населения, подверженного действию пестицидов, выявили высокую частоту хромосомных аберраций, превышающую контрольные показатели от 2,2 до 3,6 раз. Молекулярно-генетический анализ выявил повышенную частоту нефункциональных аллелей глутатион-S-трансфераз M1 и Т1 типов, что может оказывать влияние на снижение функций детоксикации ксенобиотиков у обследованного населения. Определена достоверная ассоциативная связь полиморфизма гена репарации ДНК XRCC3 Thr241Met, с повышенной частотой хромосомных аберраций у населения, проживающего вблизи очагов пестицидного загрязнения. The risk assessment of the impact of long-term pesticide pollution of the environment on the genetic status of the population living in 5 settlements of the Talgar district (Kyzylkairat, Beskaynar, Belbulak, Amangeldy, Enbekshi) of Almaty region, where unused, banned for use POPs pesticides are located, has been carried out. The results of cytogenetic analysis of the population exposed to pesticides revealed a high frequency of chromosomal aberrations, exceeding the control values from 2.2 to 3.6 times. Molecular genetic analysis revealed an increased frequency of non-functional alleles of glutathione-S-transferases of M1 and T1 types, which may affect a decrease in the functions of detoxification of xenobiotics in the surveyed population. A reliable associative relationship of the XRCC3 Thr241Met DNA repair gene polymorphism with an increased frequency of chromosomal aberrations in the population living near foci of pesticide contamination was determined.