Biochemical Mechanisms Of Resistance Research Articles

Deciphering Host-Parasite Interplay in Leishmania Infection through a One Health View of Proteomics Studies on Drug Resistance.

Recent efforts in the study of vector-borne parasitic diseases (VBPDs) have emphasized an increased consideration for preventing drug resistance and promoting the environmental safety of drugs, from the beginning of the drug discovery pipeline. The intensive use of the few available antileishmanial drugs has led to the spreading of hyper-resistant Leishmania infantum strains, resulting in a chronic burden of the disease. In the present work, we have investigated the biochemical mechanisms of resistance to antimonials, paromomycin, and miltefosine in three drug-resistant parasitic strains from human clinical isolates, using a whole-cell mass spectrometry proteomics approach. We identified 14 differentially expressed proteins that were validated with their transcripts. Next, we employed functional association networks to identify parasite-specific proteins as potential targets for novel drug discovery studies. We used SeqAPASS analysis to predict susceptibility based on the evolutionary conservation of protein drug targets across species. MATH-domain-containing protein, adenosine triphosphate (ATP)-binding cassette B2, histone H4, calpain-like cysteine peptidase, and trypanothione reductase emerged as top candidates. Overall, this work identifies new biological targets for designing drugs to prevent the development of Leishmania drug resistance, while aligning with One Health principles that emphasize the interconnected health of people, animals, and ecosystems.

Baseline of susceptibility, risk assessment, biochemical mechanism, and fitness cost of resistance to dimpropyridaz, a novel pyridazine pyrazolecarboxamide insecticide, in Bemisia tabaci from China

Bemisia tabaci is one of the most destructive agricultural insect pests around the world, and it has developed high levels of resistance to most pesticides. Dimpropyridaz, a novel insecticide developed by BASF, displays excellent activity against piercing-sucking insect pests. In this study, baseline of susceptibility showed all tested field populations of B. tabaci are susceptible to dimpropyridaz. After continuous selection with dimpropyridaz in the lab, a B. tabaci strain (F12) developed 2.2-fold higher level of resistance compared with a susceptible MED-S strain, and the realized heritability (h2) was estimated as 0.0518. The F12 strain displayed little cross-resistance to afidopyropen, cyantraniliprole, sulfoxaflor, or abamectin, and significantly increased activity of cytochrome P450 monooxygenase (P450). The fitness cost of dimpropyridaz resistance was evident in F12 strain, which had a relative fitness of 0.95 and significantly lower fecundity per female compared with MED-S strain. Taken together, B. tabaci displays high susceptibility to dimpropyridaz in the field, and low risk of developing resistance to dimpropyridaz under successive selection pressure. Little cross-resistance to popular insecticides was found, and fitness cost associated dimpropyridaz resistance was observed. Higher activity of cytochrome P450 in the F12 strain, may be involved in the process of detoxifying dimpropyridaz in whitefly.

Transcriptional activation of MdDEF30 by MdWRKY75 enhances apple resistance to Cytospora canker

Defensin is an essential component of plant development, and it plays an indispensable role in pathogen resistance. However, the molecular function of defensins under pathological conditions of Cytospora canker has not been characterized in apple plants. In the present study, we present a detail overview of phylogeny and structure of 29 defensins (MdDEF) in apple. Expression analysis revealed that MdDEF genes was spatiotemporally diverse across apple tissues. Five MdDEF genes were found to be significantly up-regulated following a challenge with Cytospora mali. The transgenic overexpression of five defensin genes in apple calli markedly enhanced resistance to C. mali. Among them, MdDEF30 was strongly induced and conferred the highest level of resistance in vivo. Meanwhile, antifungal activity assays in vitro demonstrated that a recombinant protein produced from MdDEF30 could inhibit the growth of C. mali. Notably, MdDEF30 promoted the accumulation of reactive oxygen species (ROS) and activated defense-related genes such as PR4, PR10, CML13 and MPK3. Co-expression regulatory network analysis showed that MdWRKY75 may regulate the expression of MdDEF30. Further yeast one-hybrid (Y1H), luciferase, and chromatin Immunoprecipitation quantitative polymerase chain reaction (ChIP-qPCR) assays verified that MdWRKY75 could directly bind to the promoter of MdDEF30. Importantly, pathogen inoculation assays confirmed that MdWRKY75 positively regulates resistance by transcriptionally activating MdDEF30. Taken together, these results demonstrated that MdDEF30 promotes resistance to C. mali in apple plants and that MdWRKY75 regulates MdDEF30 expression during the induction of resistance, thereby clarifying biochemical mechanisms of resistance to C. mali in apple trees.

Risk assessment, cross-resistance, biochemical mechanism and fitness cost of tetraniliprole resistance in the tomato pinworm Tutaabsoluta

Tuta absoluta is one of the most devastating and invasive insect pests throughout the world. It feeds on numerous solanaceous plant species and has evolved resistance to various types of popular chemical agents. Tetraniliprole is a novel diamide chemical agent that acts as a modulator of the ryanodine receptor, and it has been considered as a promising insecticide against T. absoluta. In this study, we subjected a T. absoluta strain to 17 generations of continuous selection with tetraniliprole in the lab. The resulting tetraniliprole-selected T. absoluta strain (YN-Tet) exhibited a 12.9-fold higher resistance to tetraniliprole compared with a susceptible strain (YN–S), and the realized heritability (h2) was estimated to be 0.1437. The YN-Tet strain exhibited a low level of cross-resistance to chlorantraniliprole and significantly higher cytochrome P450 monooxygenase activity. There was a fitness cost of tetraniliprole resistance in the YN-Tet strain, which had a relative fitness of 0.83 compared with the YN-S strain and a significantly lower fecundity per female. These results enhance our knowledge of the risk and mechanism of tetraniliprole resistance, enabling future optimization of resistance management strategies.

Ace-1 Target Site Status and Metabolic Detoxification Associated with Bendiocarb Resistance in the Field Populations of Main Malaria Vector, Anopheles stephensi in Iran.

Anopheles stephensi is the main vector of malaria in Iran. This study aimed to determine the susceptibility of An. stephensi from the south of Iran to bendiocarb and to investigate biochemical and molecular resistance mechanisms in this species. Wild An. stephensi were collected from Hormozgan Province and reared to the adult stage. The susceptibility test was conducted according to the WHO protocols using bendiocarb impregnated papers supplied by WHO. Also, field An. Stephensi specimens were collected from south of Kerman and Sistan and Baluchistan Provinces. To determine the G119S mutation in the acetylcholinesterase (Ace1) gene, PCR-RFLP using AluI restriction enzyme and PCR direct-sequencing were performed for the three field populations and compared with the available GenBank data. Also, biochemical assays were performed to measure alpha and beta esterases, insensitive acetylcholinesterase, and oxidases in the strains. The bioassay tests showed that the An. stephensi field strain was resistant to bendiocarb (mortality rate 89%). Ace1 gene analysis revealed no G119S in the three field populations. Blast search of sequences revealed 98-99% identity with the Ace1 gene from Pakistan and India respectively. Also, the results of biochemical tests revealed the high activity of non-sensitive acetylcholinesterase, alpha and beta-esterase in the resistant strain compared to the susceptible strain. No G119S was detected in this study additionally the enhanced enzyme activity of esterases and acetylcholinesterase suggesting that resistance was metabolic. The use of alternative malaria control methods and the implementation of resistance management strategies are suggested in the study area.

DISSECTING BIOCHEMICAL MECHANISMS THAT MEDIATE TOLERANCE TO MILITARY CHEMICAL STRESSORS IN DIVERSE MALACOLOGICAL SYSTEMS

The ongoing military conflict in Ukraine has severely contaminated freshwater ecosystems with heavy metal pollutants including lead from ammunition and explosives. This study investigates the physiological and biochemical mechanisms of resistance in the freshwater mollusks. This study examines how freshwater mollusks, specifically Planorbarius corneus and Viviparus viviparus, resist lead compounds. Lead pollution from military activities poses a significant threat to aquatic life due to its toxicity and bioaccumulation. The research investigated species-specific responses to lead exposure, revealing differences in adaptations. Both mollusk species showed increased levels of carotenoids and proteins when exposed to higher lead concentrations, indicating a compensatory response to oxidative stress. These findings enhance our understanding of adaptive mechanisms against lead toxicity in aquatic environments affected by military pollution.

Transcriptomic and metabolomic analyses reveals keys genes and metabolic pathways in tea (Camellia sinensis) against six-spotted spider mite (Eotetranychus Sexmaculatus)

BackgroundSix-spotted spider mite (Eotetranychus sexmaculatus) is one of the most damaging pests of tea (Camellia sinensis). E. sexmaculatus causes great economic loss and affects tea quality adversely. In response to pests, such as spider mites, tea plants have evolved resistance mechanisms, such as expression of defense-related genes and defense-related metabolites.ResultsTo evaluate the biochemical and molecular mechanisms of resistance in C. sinensis against spider mites, “Tianfu-5” (resistant to E. sexmaculatus) and “Fuding Dabai” (susceptible to E. sexmaculatus) were inoculated with spider mites. Transcriptomics and metabolomics based on RNA-Seq and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) technology were used to analyze changes in gene expression and metabolite content, respectively.RNA-Seq data analysis revealed that 246 to 3,986 differentially expressed genes (DEGs) were identified in multiple compared groups, and these DEGs were significantly enriched in various pathways, such as phenylpropanoid and flavonoid biosynthesis, plant–pathogen interactions, MAPK signaling, and plant hormone signaling. Additionally, the metabolome data detected 2,220 metabolites, with 194 to 260 differentially abundant metabolites (DAMs) identified in multiple compared groups, including phenylalanine, lignin, salicylic acid, and jasmonic acid. The combined analysis of RNA-Seq and metabolomic data indicated that phenylpropanoid and flavonoid biosynthesis, MAPK signaling, and Ca2+-mediated PR-1 signaling pathways may contribute to spider mite resistance.ConclusionsOur findings provide insights for identifying insect-induced genes and metabolites and form a basis for studies on mechanisms of host defense against spider mites in C. sinensis. The candidate genes and metabolites identified will be a valuable resource for tea breeding in response to biotic stress.

Recent Advances in the Genetic and Biochemical Mechanisms of Rice Resistance to Brown Planthoppers (Nilaparvata lugens Stål)

Rice (Oryza sativa L.) is the staple food of more than half of Earth’s population. Brown planthopper (Nilaparvata lugens Stål, BPH) is a host-specific pest of rice responsible for inducing major losses in rice production. Utilizing host resistance to control N. lugens is considered to be the most cost-effective method. Therefore, the exploration of resistance genes and resistance mechanisms has become the focus of breeders’ attention. During the long-term co-evolution process, rice has evolved multiple mechanisms to defend against BPH infection, and BPHs have evolved various mechanisms to overcome the defenses of rice plants. More than 49 BPH-resistance genes/QTLs have been reported to date, and the responses of rice to BPH feeding activity involve various processes, including MAPK activation, plant hormone production, Ca2+ flux, etc. Several secretory proteins of BPHs have been identified and are involved in activating or suppressing a series of defense responses in rice. Here, we review some recent advances in our understanding of rice–BPH interactions. We also discuss research progress in controlling methods of brown planthoppers, including cultural management, trap cropping, and biological control. These studies contribute to the establishment of green integrated management systems for brown planthoppers.

Cross-resistance, inheritance and biochemical mechanism of abamectin resistance in a field-derived strain of the citrus red mite, Panonychus citri (Acari: Tetranychidae).

The citrus red mite, Panonychus citri (McGregor), a global pest of citrus, has developed different levels of resistance to various acaricides in the field. Abamectin is one of the most important insecticides/acaricides worldwide, targetting a wide number of insect and mite pests. The evolution of abamectin resistance in P. citri is threatening the sustainable use of abamectin for mite control. The abamectin resistant strain (NN-Aba), derived from a field strain NN by consistent selection with abamectin, showed 4279-fold resistance to abamectin compared to a relatively susceptible strain (SS) of P. citri. Cross-resistance of NN-Aba was observed between abamectin and emamectin benzoate, pyridaben, fenpropathrin and cyflumetofen. Inheritance analyses indicated that abamectin resistance in the NN-Aba strain was autosomal, incompletely recessive and polygenic. The synergy experiment showed that abamectin toxicity was synergized by piperonyl butoxide (PBO), diethyl maleate (DEM) and tributyl phosphorotrithiotate (TPP) in the NN-Aba strain, and synergy ratios were 2.72-, 2.48- and 2.13-fold, respectively. The glutathione-S-transferases activity in the NN-Aba strain were significantly increased by 2.08-fold compared with the SSstrain. The abamectin resistance was autosomal, incompletely recessive and polygenic in P. citri. The NN-Aba strain showed cross-resistance to various acaricides with different modes of action. Metabolic detoxification mechanism participated in abamectin resistance in NN-Aba strain. These findings provide useful information for resistance management of P. citri in the field. © 2023 Society of Chemical Industry.

Acaricide resistance in predatory mites of the genus Euseius (Acari: Phytoseiidae) and predation capacity on Brevipalpus yothersi (Acari: Tenuipalpidae)

One of the main citrus diseases in Brazil is citrus leprosis, transmitted by the mite Brevipalpus yothersi Baker (Acari: Tenuipalpidae). The predatory mites Euseius citrifolius Denmark & Muma and Euseius concordis (Chant) (Acari: Phytoseiidae) are important natural enemies for the pest mite. The objective of this work was to evaluate the susceptibility of different populations of E. concordis and E. citrifolius, from citrus groves in the state of São Paulo (SP), to the acaricides abamectin, fenpropathrin and chlorfenapyr; characterize the abamectin resistance in E. citrifolius, including studies on cross-resistance and biochemical mechanisms of resistance; and evaluate the predation capacity of an abamectin resistant population of E. citrifolius on B. yothersi. Significant differences in susceptibility to acaricides were observed among populations of E. citrifolius. Resistance ratios of 15.5 and 3.1 (times) were observed for abamectin and chlorfenapyr, respectively, comparing populations of E. citrifolius collected in the municipalities of Taquaral-SP and Bofete-SP. Studies with the synergist piperonyl butoxide indicated the involvement of cytochrome P450-dependent monooxygenases in the resistance of E. citrifolius to abamectin. Populations of E. concordis and E. citrifolius collected in Taquaral-SP showed low susceptibility to fenpropathrin, with LC50 values at least 95 times higher than the recommended concentration for the control of Brevipalpus mites in citrus in Brazil. The population of E. citrifolius from Taquaral showed a high capacity for predation of B. yothersi larvae, with consumption of up to 49.4 larvae per adult female per day.

Searching for Life on Venus: History of the Problem and Basic Concepts

Venus has always been one of the priorities of the space research program in Russia. The history of successful investigations of Venus in the Soviet Union is primarily associated with delivering a whole series of spacecraft to it and implementing the first ever landing on its surface. In the last few years, the study of Venus in astrobiological direction has been rapidly developing. To date, a fairly large number of theoretical papers have been published, the main purpose of which is to estimate the possibility of the existence of living organisms on Venus. The most likely ecosystem, in which Earth-type organisms could develop, is considered to be a dense cloud layer of Venus. It is supposed that, in this layer, hypothetical microbial communities could exist in aerosols being a concentrated aqueous solution of sulfuric acid. Microorganisms in such a specific air habitat are to be exposed to several extreme factors at once, the main among which are very low values of pH and water activity. The principal strategies for survival under these conditions should be the availability of effective biochemical mechanisms of resistance to the impact of adverse environmental factors and the use of all possible ways of extracting energy in such an ecosystem to maintain the biomass of organisms at a level for stable reproduction.

Resistance to Beta-cypermethrin, Azadirachtin, and Matrine, and Biochemical Characterization of Field Populations of Oedaleus asiaticus (Bey-Bienko) in Inner Mongolia, Northern China.

Oedaleus asiaticus (Bey-Bienko) is an economically devastating locust species found in grassland and pastoral areas of the Inner Mongolia region of northern China. In this study, resistance to three frequently used insecticides (beta-cypermethrin, matrine, and azadirachtin) was investigated in six field populations of O. asiaticus using the leaf-dip bioassay method. The inhibitory effects of synergists and the activities of detoxification enzyme activities in the different populations were determined to explore potential biochemical resistance mechanisms. The results showed that the field populations SB (resistance ratio [RR] = 7.85), ZB (RR = 5.64), and DB (RR = 6.75) had developed low levels of resistance to beta-cypermethrin compared with a susceptible control strain. Both the SB (RR = 5.92) and XC (RR = 6.38) populations had also developed low levels of resistance against matrine, with the other populations remaining susceptible to both beta-cypermethrin and matrine. All field populations were susceptible to azadirachtin. Synergism analysis showed that triphenyl phosphate (TPP) and diethyl-maleate (DEM) increased the toxicity of beta-cypermethrin significantly in the SB population, while the synergistic effects of TPP, piperonyl butoxide (PBO), and DEM on the toxicity of matrine were higher in SB (SR 3.86, 4.18, and 3.07, respectively) than in SS (SR 2.24, 2.86, and 2.29, respectively), but no synergistic effects of TPP, PBO, and DEM on azadirachtin were found. Biochemical assays showed that the activities of carboxylesterases (CarEs) and glutathione-S-transferases (GSTs) were significantly raised in all field populations of O. asiaticus, with a significant positive correlation observed between beta-cypermethrin resistance and CarE activity. The activities of cytochrome P450 monooxygenases (P450) and multi-function oxidases (MFO) were elevated in all six field populations, and P450 activity displayed strong positive correlations with the three insecticides. Our findings suggest that resistance to beta-cypermethrin in O. asiaticus may be mainly attributed to elevated CarE and GST activities, while P450 plays an important role in metabolizing matrine and azadirachtin. Our study provides insights that will help improve insecticide resistance management strategies.

Acetamiprid Resistance in the Green Peach Aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae): Selection, Cross-Resistance, Biochemical and Molecular Resistance Mechanisms

Myzus persicae (Sulzer) (Hemiptera: Aphididae) is a polyphagous pest that causes significant losses in many crops. In the present study, the biochemical and molecular mechanism of acetamiprid resistance in a laboratory-selected Myzus persicae population of which the resistance ratios reached 57.5-fold were investigated. This study was conducted in the Isparta University of Applied Sciences, Agriculture Faculty, Department of Plant Protection in 2018 and 2020. Synergism, biochemical and molecular assays showed the absence of increased P450 activity in selected population. In addition, no point mutation in nicotinic acetylcholine receptor (nAChR), the target-site of neonicotinoids including acetamiprid, was detected in the selected population. These results suggests that high level of acetamiprid resistance might be developed via the mechanisms other than well-known mechanisms, such as increased P450 activity and target-site mutations. The population selected with acetamiprid showed decreased susceptibility to imidacloprid, sulfaxaflor, beta-cyfluthrin, and tau-fluvanite ranging from 1.54 to 4.76. Nonetheless, more studies are needed to support cross-resistance by Myzus persicae populations having different genetic backgrounds.

Detoxification enzyme activity, reproductive and developmental fitness of abamectin-resistant Bryobia praetiosa (Acari:Tetranychidae)

Abamectin is an important and environmentally friendly antibiotic pesticide, and its resistance has become an area of intense research. In this study, we employed laboratory bioassays, biochemical analyses, and life history analyses to systematically evaluate abamectin resistance, the underlying biochemical mechanisms of resistance, and the reproductive and developmental characteristics of the arthropod pest Bryobia praetiosa. An abamectin-resistant B. praetiosa strain (RR) was obtained by intensive selection of an abamectin-susceptible strain (SS) using abamectin exposure in the laboratory for 24 generations, yielding a resistance index (RI) of 30.11. Comparison of detoxification enzymes suggested that the specific activities of carboxylesterases (CarEs), glutathione S-transferases (GSTs), and mixed-function oxidases (MFOs) in the RR strain were higher than those of the SS strain by 1.13-, 1.75-, and 4.02-fold, respectively. GST and MFOS protein concentrations were also significantly different between RR and SS strains. Further analysis of life history parameters demonstrated that the developmental duration and lifespan of RR strain in addition to egg numbers were markedly decreased relative to SS strain. The net reproductive rate (R0), finite rate of increase (λ), and population doubling time (Dt) of RR strain were significantly lower than those of SS strain. The results indicated that the RR strain was more disadvantageous in developmental and reproductive characteristics than the SS strain. In addition, the relative fitness value of the resistant strain is about half (Rf = 0.49) that of the susceptible strain. In conclusion, increased abamectin resistance in B. praetiosa was associated with a rapid increase in MFOs activity, while GSTs also played a role in abamectin resistance development and RR strain exhibited reproductive disadvantages.

Molecular and Biochemical Detection of Insecticide Resistance in the Leishmania Vector, Phlebotomus papatasi (Diptera: Psychodidae) to Dichlorodiphenyltrichloroethane and Pyrethroids, in Central Iran.

The aim of the present study was to explore resistance markers and possible biochemical resistance mechanisms in the Phlebotomine sand fly Phlebotomus papatasi in Esfahan Province, central Iran. Homogenous resistant strains of sand flies were obtained by exposing P. papatasi collected from Esfahan to a single diagnostic dose of DDT. The adults from the colony were tested with papers impregnated with four pyrethroid insecticides: Permethrin 0.75%, Deltamethrin 0.05%, Cyfluthrin 0.15%, and Lambdacyhalothrin 0.05% to determine levels of cross-resistance. To discover the presence of mutations, a 440 base pair fragment of the voltage gated sodium channel (VGSC) gene was amplified and sequenced in both directions for the susceptible and resistant colonies. We also assayed the amount of four enzymes that play a key role in insecticide detoxification in the resistant colonies. A resistance ratio (RR) of 2.52 folds was achieved during the selection of resistant strains. Sequence analysis revealed no knockdown resistance (kdr) mutations in the VGSC gene. Enzyme activity ratio of the resistant candidate and susceptible colonies were calculated for α-esterases (3.78), β-esterases (3.72), mixed function oxidases (MFO) (3.21), and glutathione-S-transferases (GST) (1.59). No cross-resistance to the four pyrethroids insecticides was observed in the DDT resistant colony. The absence of kdr mutations in the VGSC gene suggests that alterations in esterase and MFO enzymes are responsible for the resistant of P. papatasi to DDT in central Iran. This information could have significant predictive utility in managing insecticide resistant in this Leishmania vector.

Biochemical mechanisms of induced resistance to Chilo partellus in sorghum

Host plant resistance is an important component of pest management, and information on contribution of different mechanisms of resistance is important for developing cultivars with resistance to the target pests. Therefore, induced resistance was studied in five sorghum genotypes against Chilo partellus by using infested and non-infested plants under greenhouse conditions. The activity of plant defensive enzymes and the secondary metabolites were recorded at 7 days after infestation and their induction varied among the genotypes and treatments. The resistant sorghum genotypes ICSV 700, IS 2205 and ICSV 93046 suffered lower leaf damage by the neonate larvae of C. partellus (damage rating (DR) 2.8–3.7) as compared to the susceptible checks, ICSV 1 and Swarna (DR 6.4 and 7.0, respectively). ICSV 700, IS 2205 and ICSV 93046 exhibited greater enzymatic activity [peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL)] and had more amounts of phenols than the susceptible check, Swarna. This information will be useful for developing sorghum genotypes with resistance to C. partellus for sustainable crop production. Supplemental data for this article is available online at https://doi.org/10.1080/09670874.2022.2036863 .

Changes in biochemistry and cellular ultrastructure support different resistance mechanisms to Phytophthora sojae in nonhost common bean and host soybean

AbstractPhytophthora root and stem rot of soybean caused by Phytophthora sojae is a destructive disease affecting soybean production worldwide. In nature, soybean is the only economically important cultivated host of P. sojae. The aim of this study was to explain different resistance mechanisms to P. sojae in nonhost common bean and host soybean as a basis for the control of Phytophthora root and stem rot of soybean via nonhost resistance. Observations and measurements of disease resistance‐related variables showed slight differences in structural and biochemical resistance mechanisms between common bean and soybean. P. sojae infection induced a stronger hypersensitive response in nonhost common bean than in host resistant soybean. Moreover, phytoalexin phaseollidin synthesis‐related vestitone reductase gene was extremely highly up‐regulated, and phytoalexin glyceollin synthesis‐related isoflavone reductase gene was slightly less up‐regulated in common bean than in soybean, which resulted in a higher level of phaseollidin and a lower level of glyceollin in common bean. Phaseollidin had stronger inhibitory effects on mycelial growth and oospore formation of P. sojae than glyceollin, and more cell wall depositions and callose accumulated in common bean, which are probably related to the stronger resistance of nonhost common bean to P. sojae.

Terpenoids of plants in arid environments

Abstract Arid and desert environments are characterized by the sparse and discontinuous vegetation cover. Species that have been able to survive difficult bioclimatic conditions and adapt from generation to generation in these areas had to develop physiological and biochemical mechanisms of tolerance and/or resistance. The use of secondary metabolites, specifically terpenoids, is predominant in most of the biotic and abiotic interactions in which these plants are involved. Studies have shown their roles in the prevention of oxidative stress by intervening in thermo-tolerance, water stress, and salt stress generalized in a model of "the protective role of volatile compounds" explained by a single biochemical mechanism. Other studies have proven the functions of terpenoids in direct and indirect defenses against natural enemies, herbivores, and pathogenic microorganisms, in the attraction of pollinators, in competition and facilitation and other interactions between plants. This review mainly summarizes the recent research progress on the adaptation mechanisms of plants in arid environments and the biological and ecological roles of terpenoids in the various biotic and abiotic interactions.

Comparative analysis of iron oxide nanoparticles synthesized from ginger (Zingiber officinale) and cumin seeds (Cuminum cyminum) to induce resistance in wheat against drought stress

In the present study, iron oxide nanoparticles (Fe3O2-NPs) synthesized from ginger (Zingiber officinale) and cumin seeds (Cuminum Cyminum L.) extracts were investigated to reveal their potential to enhance the growth and drought resistance of wheat plants under drought stress. In an In Vitro experiment, four different concentrations for Fe3O2-NPs (0.3 mM, 0.6 mM, 0.9 mM, and 1.2 mM) of ginger and cumin seeds were tested. Among all the concentrations tested, ginger Fe3O2-NPs (0.6 mM) and cumin seeds Fe3O2-NPs (1.2 mM) were more effective to enhance wheat germination, biomass, and survival percentage under drought stress and irrigated conditions than the non-treated control plant. In a pot experiment, wheat plants under induced water stress showed marked up-regulation in the biochemical resistance mechanisms when treated with ginger Fe3O2-NPs (0.6 mM) and cumin seeds Fe3O2-NPs (1.2 mM) than the non-treated control. Cumin seeds Fe3O2-NPs (1.2 mM) were more effective than ginger Fe3O2-NPs (0.6 mM) in ameliorating adverse effects of drought stress in wheat. Results demonstrated that cumin seeds Fe3O2-NPs (1.2 mM) exhibited a higher increase in chlorophyll a, b and carotenoids (72%, 265% and 96% respectively), proline (127%), superoxide dismutase (115%), peroxidase (43.8%), ascorbate peroxidase (44.6%). This also showed higher reduction in lipid peroxidation, electrolyte leakage and increased soluble sugars and total Fe content in the roots and shoots than non-treated plants under drought. Hence, nano-priming can be considered an effective strategy for sustainable food production in marginal soils.

Defensive responses of Populus deltoides cl. Beikang to mechanical injury and Anoplophora glabripennis infection.

Poplar, as the main tree species of the protection forest in the "Three-North" area of China, has been seriously damaged by Anoplophora glabripennis since 1970s. Populus deltoides cl. Beikang (PDB) shows strong resistance to A. glabripennis, but the biochemical mechanism of resistance is unclear. In this study, the quantities of secondary metabolites and the activity of defense enzymes in bark and xylem from undamaged, mechanically damaged, and A. glabripennis infected PDB were detected by kit and HPLC techniques. The results showed different responses of PDB to mechanical damage and A. glabripennis infection. Secondary metabolites, the quantities of D-(-)-salicin and aspen significantly increased after mechanical injury compared with the undamaged materials, but the quantities of quercitrin decreased. The quantities of D-(-)-salicin and quercitrin significantly increased after insect infection, but without difference for aspen. There was no significant difference for the total quantities of phenolics between insect infected and uninjured xylem, but both were significantly lower than that in the mechanical damaged xylem. The quantities of aspen and flax lignans in the insect infected xylem was higher than those in the mechanical damaged xylem and uninjured xylem, while the quantities of total phenolic glycosides in the mechanical damaged xylem and the insect infected xylem were both significantly higher than that in the uninjured xylem. PAL activity was not different between mechanical damage and insect infection, whereas both were significantly higher than that of uninjured bark. SOD activity in mechanical damaged bark was significantly higher than that in insect infected bark, which were both higher than that of uninjured bark. POD activity had no significant difference between mechanical damage and insect infected xylem, but were higher than that of uninjured xylem. Compared with the uninjured PDB tree, the secondary metabolites and defense enzymes in the mechanical damaged and A. glabripennis infected PDB increased in varied degrees, which would be related with the resistance of PDB to external injury.