Defensive Secondary Metabolites Research Articles

Endophytic Microbial Community Structure and Dynamics Influence Agarwood Formation in Aquilaria malaccensis Lam.

Aquilaria malaccensis Lam., an Agarwood-producing tree native to Southeast Asia, secretes oleoresin, a resin with diverse applications, in response to injuries. To explore the role of endosphere microbial communities during Agarwood development, we utilized a metagenomics approach across three stages: non-symptomatic (NC), symptomatic early (IN), and symptomatic mature (IN1). The NC metagenome was dominated by Bacillus (19.15%), Klebsiella (13.25%), and Pantoea (12.46%) among bacteria and Saccharomyces (15.92%) among fungi. Notably, bacterial chemotaxis pathway genes were more prevalent in NC (2.14%) compared to IN (0.92%) and IN1 (1.16%), suggesting microbial chemotactic behavior. In the IN stage, Klebsiella (27.05%) and Saccharomyces (34.81%) were the dominant genera. The IN1 metagenome featured Pantoea (8.92%) and Neurospora (8.24%) as leading bacterial and fungal genera, respectively. Functional genes associated with defense mechanisms, lipid transport, and secondary metabolite biosynthesis were increasingly represented in IN1, indicating an enhanced microbial response as infection progresses. Ecological indices, including a high Shannon-Wiener index (H' = 4.467) and Simpson's dominance (1 - D = 0.9697), alongside Pielou's evenness index (J = 0.7034), highlighted a dynamic and diverse microbial community at the mature infection stage, reflecting the complex interactions within the Aquilaria endosphere during Agarwood formation.

PRP5 Induction by Infection of Pythium Sp. in Tomato

The Pseudomonas fluorescens isolate FP 7 was found to protect the tomato plants against soil borne fungus, Pythium aphanidermatum. The ability to induce defense proteins viz. -1,3 glucanase, peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) by this P. fluorescens isolate FP 7 against P. aphanidermatum fungus was further studied. Increased activity of PO, PPO and -1,3 glucanase were observed in plants pretreated with FP 7 isolate. Native PAGE (polyacrylamide gel electrophoresis) of PO showed the single isoform in all the treatment including the control and difference is by the increased intensity of the band in the inoculated control and FP 7 treatment in the tomato plant. Isoform analysis of the PPO showed the induction of the PPO in the P. fluorescens treated plants challenged with P. aphanidermatum. -1,3 glucanase in tomato cultivar, Co 3 with and without challenge inoculation of P. aphanidermatum, revealed changes in the isoform pattern after staining the gel with 2,3,5-triphenyl tetrazolium chloride. Moreover, higher accumulation of phenolics was noticed in plants pretreated with P. fluorescens isolate FP 7 challenged with P. aphanidermatum. The relevant function of Thaumatin like defense proteins and secondary metabolites involved in the phenylpropanoid pathway collectively contributing to enhanced resistance is discussed.

Combined transcriptomic and metabolomic analysis of the mechanism by which Bacillus velezensis induces resistance to anthracnose in walnut.

Walnut (Juglans spp.), a significant deciduous tree of economic and ecological importance, faces substantial threats from walnut anthracnose, primarily caused by Colletotrichum gloeosporioides. Bacillus velezensis has shown promise in mitigating this fungal pathogen. To delve deeper into the induction mechanism of B. velezensis on walnut plant resistance, we conducted a metabolomic analysis on walnut leaves from six different treatment groups. Specifically, the groups were defined as follows: Group B.v. was inoculated with B. velezensis alone, Group CK served as the blank control, and Group C.g. was inoculated solely with C. gloeosporioides. Group B.v.-C.g. received B. velezensis followed by C. gloeosporioides inoculation. Group B.v.+C.g. underwent simultaneous inoculation with both B. velezensis and C. gloeosporioides, while Group C.g.-B.v. was treated first with C. gloeosporioides then B. velezensis. A total of 1,503 metabolites were detected, mainly including flavonoids, terpenoids, and steroids. The results revealed that B. velezensis spraying not only enhanced the inherent resistance of walnut plants but also significantly regulated walnut plants already infected with C. gloeosporioides. This was mainly achieved by inducing walnut plants to adjust their metabolic pathways such as salicylic acid, jasmonic acid, and abscisic acid, thereby strengthening their stress response. Transcriptomic and metabolomic correlation analyses showed that in the comparisons of B.v. vs. CK, C.g. vs. CK, and C.g.-B.v. vs. C.g., 59, 244, and 122 differential abundance metabolites were detected, along with 7860, 3677, and 5587 differential genes, respectively. Amino acid synthesis, starch and sucrose metabolism, photosynthesis, phenylpropane metabolism, purine metabolism, and glutathione metabolism played crucial roles in walnut's disease resistance mechanism. Further analysis revealed that B. velezensis induced walnut plants to regulate multiple genes, such as LOC109005403, LOC108985444 and LOC118344177, resulting in the production of defensive metabolites such as palmitic acid, coumarin and ferulic acid, thereby enhancing their resistance to C. gloeosporioides. In summary, B. velezensis induces systemic resistance in walnut plants by modulating the metabolic pathways of salicylic acid, jasmonic acid, and abscisic acid. It enhances this resistance by strengthening cell walls, synthesizing defensive secondary metabolites, and regulating energy metabolism and stress responses. These findings provide a solid theoretical foundation for the future field application of B. velezensis in controlling walnut anthracnose.

Extensive Genomic Rearrangement of Catalase-Less Cyanobloom-Forming Microcystis aeruginosa in Freshwater Ecosystems.

Many of the world's freshwater ecosystems suffer from cyanobacteria-mediated blooms and their toxins. However, a mechanistic understanding of why and how Microcystis aeruginosa dominates over other freshwater cyanobacteria during warmer summers is lacking. This paper utilizes comparative genomics with other cyanobacteria and literature reviews to predict the gene functions and genomic architectures of M. aeruginosa based on complete genomes. The primary aim is to understand this species' survival and competitive strategies in warmer freshwater environments. M. aeruginosa strains exhibiting a high proportion of insertion sequences (~ 11%) possess genomic structures with low synteny across different strains. This indicates the occurrence of extensive genomic rearrangements and the presence of many possible diverse genotypes that result in greater population heterogeneities than those in other cyanobacteria in order to increase survivability during rapidly changing and threatening environmental challenges. Catalase-less M. aeruginosa strains are even vulnerable to low light intensity in freshwater environments with strong ultraviolet radiation. However, they can continuously grow with the help of various defense genes (e.g., egtBD, cruA, and mysABCD) and associated bacteria. The strong defense strategies against biological threats (e.g., antagonistic bacteria, protozoa, and cyanophages) are attributed to dense exopolysaccharide (EPS)-mediated aggregate formation with efficient buoyancy and the secondary metabolites of M. aeruginosa cells. Our review with extensive genome analysis suggests that the ecological vulnerability of M. aeruginosa cells can be overcome by diverse genotypes, secondary defense metabolites, reinforced EPS, and associated bacteria.

Glucosinolate structural diversity shapes recruitment of a metabolic network of leaf-associated bacteria

Host defenses can have broader ecological roles, but how they shape natural microbiome recruitment is poorly understood. Aliphatic glucosinolates (GLSs) are secondary defense metabolites in Brassicaceae plant leaves. Their genetically defined structure shapes interactions with pests in Arabidopsis thaliana leaves, and here we find that it also shapes bacterial recruitment. In model genotype Col-0, GLSs (mostly 4-methylsulfinylbutyl-GLS) have no clear effect on natural leaf bacterial recruitment. In a genotype from a wild population, however, GLSs (mostly allyl-GLS) enrich specific taxa, mostly Comamonadaceae and Oxalobacteraceae. Consistently, Comamonadaceae are also enriched in wild A. thaliana, and Oxalobacteraceae are enriched from wild plants on allyl-GLS as carbon source, but not on 4-methylsulfinylbutyl-GLS. Recruitment differences between GLS structures most likely arise from bacterial myrosinase specificity. Community recruitment is then defined by metabolic cross-feeding among bacteria. The link of genetically defined metabolites to recruitment could lead to new strategies to shape plant microbiome balance.

Role of defense inducers in modulating biochemical responses to Alternaria leaf blight

Alternaria leaf blight of sunflower has been considered as a potentially destructive disease. Due to cons of using chemical pesticides, the present investigation was undertaken to know the effect of three plant defence inducers viz., salicylic acid, monopotassium phosphate and sodium propionate for the eco-friendly management of Alternaria leaf blight disease. Seed treatment with salicylic acid at 100 ppm followed by foliar spray of salicylic acid at 100 ppm recorded highest secondary metabolites such as flavonoids (68.71 mg g FW) and phenols (73.53 mg g FW) -1 -1 -1 when compared to phenolics (45.07 mg g FW) and flavonoids (51.43 mg g FW) in control plants -1 . Seed treatment with salicylic acid at 100 ppm followed by foliar spray of salicylic acid at 100 ppm showed increased defense enzymes such as superoxide dismutase (40.45 mg/50 per cent inhibition) and peroxidase (16.86 mg min mg protein) when compared to superoxide dismutase -1 -1 (54.36 mg/50 per cent inhibition) and peroxidase (9.63 mg min mg protein) in control plants. This study -1 -1 demonstrated that seed treatment followed by foliar spray with salicylic acid can be used effectively for the management of Alternaria blight in fields as it exhibited more defense enzyme activity and secondary metabolites.. KEYWORDS :Alternaria, defense enzymes, secondary metabolites, seed treatment

Identification and in vivo functional analysis of furanocoumarin-responsive cytochrome P450s in a Rutaceae-feeding Papilio butterfly.

The Order Lepidoptera contains nearly 160,000 described species and most of them are specialist herbivores that use restricted plant species as hosts. Speciation that originated from host shift is one of the important factors for the diversification of Lepidoptera. Because plants prepare secondary metabolites for defense against herbivores, with varying profiles of the components among different plant taxa, the specialist herbivores need to be adapted to the toxic substances unique to their host plants. Swallowtail butterflies of the genus Papilio consist of over 200 species. Approximately 80% of them utilize Rutaceae plants, and among the remaining species, a specific subgroup uses phylogenetically distant Apiaceae plants as larval hosts. Rutaceae and Apiaceae commonly contain toxic secondary metabolites, furanocoumarins, and molecular phylogenetic studies support the concept that Apiaceae feeders were derived from Rutaceae feeders. Molecular mechanisms underlying furanocoumarin tolerance in Papilio butterflies have been investigated almost exclusively in an Apiaceae feeder by an in vitro assay. In contrast, there is little information regarding the Rutaceae feeders. Here, we focused on a Rutaceae feeder, Papilio xuthus, and identified two furanocoumarin-responsive cytochrome P450-6B (CYP6B) genes, of which one was an ortholog of a furanocoumarin-metabolizing enzyme identified in the Apiaceae-feeding Papilio while the other was previously unreported. We further conducted in vivo functional analysis using the CRISPR/Cas9 system, revealing a contribution of these CYP6Bs to furanocoumarin tolerance of P. xuthus larvae. Our findings suggest that co-option of furanocoumarin-metabolizing CYP6B enzymes at least partially contributed to the host shift from Rutaceae to Apiaceae in Papilio butterflies.

Genomic insights into the evolution of secondary metabolism of Escovopsis and its allies, specialized fungal symbionts of fungus-farming ants.

The metabolic intimacy of symbiosis often demands the work of specialists. Natural products and defensive secondary metabolites can drive specificity by ensuring infection and propagation across host generations. But in contrast to bacteria, little is known about the diversity and distribution of natural product biosynthetic pathways among fungi and how they evolve to facilitate symbiosis and adaptation to their host environment. In this study, we define the secondary metabolism of Escovopsis and closely related genera, symbionts in the gardens of fungus-farming ants. We ask how the gain and loss of various biosynthetic pathways correspond to divergent lifestyles. Long-read sequencing allowed us to define the chromosomal features of representative Escovopsis strains, revealing highly reduced genomes composed of seven to eight chromosomes. The genomes are highly syntenic with macrosynteny decreasing with increasing phylogenetic distance, while maintaining a high degree of mesosynteny. An ancestral state reconstruction analysis of biosynthetic pathways revealed that, while many secondary metabolites are shared with non-ant-associated Sordariomycetes, 56 pathways are unique to the symbiotic genera. Reflecting adaptation to diverging ant agricultural systems, we observe that the stepwise acquisition of these pathways mirrors the ecological radiations of attine ants and the dynamic recruitment and replacement of their fungal cultivars. As different clades encode characteristic combinations of biosynthetic gene clusters, these delineating profiles provide important insights into the possible mechanisms underlying specificity between these symbionts and their fungal hosts. Collectively, our findings shed light on the evolutionary dynamic nature of secondary metabolism in Escovopsis and its allies, reflecting adaptation of the symbionts to an ancient agricultural system.IMPORTANCEMicrobial symbionts interact with their hosts and competitors through a remarkable array of secondary metabolites and natural products. Here, we highlight the highly streamlined genomic features of attine-associated fungal symbionts. The genomes of Escovopsis species, as well as species from other symbiont genera, many of which are common with the gardens of fungus-growing ants, are defined by seven chromosomes. Despite a high degree of metabolic conservation, we observe some variation in the symbionts' potential to produce secondary metabolites. As the phylogenetic distribution of the encoding biosynthetic gene clusters coincides with attine transitions in agricultural systems, we highlight the likely role of these metabolites in mediating adaptation by a group of highly specialized symbionts.

Trichomes and unique gene expression confer insect herbivory resistance in Vitis labrusca grapevines

BackgroundGrapevine (Vitis) is one of the world’s most valuable fruit crops, but insect herbivory can decrease yields. Understanding insect herbivory resistance is critical to mitigating these losses. Vitis labrusca, a wild North American grapevine species, has been leveraged in breeding programs to generate hybrid grapevines with enhanced abiotic and biotic stress resistance, rendering it a valuable genetic resource for sustainable viticulture. This study assessed the resistance of V. labrusca acc. ‘GREM4’ and Vitis vinifera cv. ‘PN40024’ grapevines to Popillia japonica (Japanese beetle) herbivory and identified morphological and genetic adaptations underlying this putative resistance.Results‘GREM4’ displayed greater resistance to beetle herbivory compared to ‘PN40024’ in both choice and no-choice herbivory assays spanning periods of 30 min to 19 h. ‘GREM4’ had significantly higher average leaf trichome densities than ‘PN40024’ and beetles preferred to feed on the side of leaves with fewer trichomes. When leaves from each species that specifically did not differ in trichome densities were fed on by beetles, significantly less leaf area was damaged in ‘GREM4’ (3.29mm2) compared to ‘PN40024’ (9.80mm2), suggesting additional factors beyond trichomes contributed to insect herbivory resistance in ‘GREM4’. Comparative transcriptomic analyses revealed ‘GREM4’ exhibited greater constitutive (0 h) expression of defense response and secondary metabolite biosynthesis genes compared to ‘PN40024’, indicative of heightened constitutive defenses. Upon herbivory, ‘GREM4’ displayed a greater number of differentially expressed genes (690) compared to ‘PN40024’ (502), suggesting a broader response. Genes up-regulated in ‘GREM4’ were enriched in terpene biosynthesis, flavonoid biosynthesis, phytohormone signaling, and disease defense-related functions, likely contributing to heighted insect herbivory defense, while genes differentially expressed in ‘PN40024’ under herbivory were enriched in xyloglucan, cell wall formation, and calcium ion binding. The majority of genes implicated in insect herbivory defense were orthologs with specific expression patterns in ‘GREM4’ and ‘PN40024’, but some paralogous and genome-specific genes also likely contributed to conferring resistance.ConclusionsOur findings suggest that ‘GREM4’ insect herbivory resistance was attributed to a combination of factors, including trichomes and unique constitutive and inducible expression of genes implicated in terpene, flavonoid, and phenylpropanoid biosynthesis, as well as pathogen defense.

Induced production of defensive secondary metabolites from Aspergillus fumigatiaffinis by co-culture with Aspergillus alabamensis

Seven previously undescribed compounds, including four diketomorpholine alkaloids (1‒4), one indole diketopiperazine alkaloid (9), one chromone (10), and one benzoic acid derivative (13), and nine known compounds (5-8, 11, 12, and 14-16) were isolated from two different fungal sources. Nine of these metabolites (1-9) were obtained from a seagrass-derived Aspergillus alabamensis SYSU-6778, while the others were obtained from a mixed culture of A. alabamensis SYSU-6778 and a co-isolated fungus A. fumigatiaffinis SYSU-6786. The chemical structures of the compounds were deduced via spectroscopic techniques (including HRESIMS, 1D and 2D NMR), chemical reactions, and ECD calculations. It is worth noting that compound 10 was identified as a defensive secondary metabolite of strain SYSU-6786, produced through the induction of compound 8 under co-culture conditions. Compounds 3 and 4 possessed a naturally rare isotryptophan core. Moreover, compounds 1 and 2 exhibited potent inhibitory activities against fish pathogenic bacterium Edwardsiella ictalurid, with minimum inhibitory concentration values of 10.0μg/mL for both compounds.

Synergistic action and mechanism of scoparone, a key bioactive component of Artemisia capillaris, and spirodiclofen against spider mites.

Plants have numerous defensive secondary metabolites to withstand insect attacks. Scoparone, which is extracted from the medicinal plant Artemisia capillaris, has potent acaricidal effects on Tetranychus cinnabarinus. Spirodiclofen, derived from a tetronic acid derivative, is a potent commercial acaricide that is extensively used globally. However, whether scoparone has synergistic effects when used in conjunction with spirodiclofen and the underlying synergistic mechanism remains unclear. Scoparone exhibited a potent synergistic effect when it was combined with spirodiclofen at a 1:9 ratio. Subsequently, cytochrome P450 monooxygenase (P450) activity, RNA-Seq and qPCR assays indicated that the enzyme activity of P450 and the expression of one P450 gene from T. cinnabarinus, TcCYP388A1, were significantly inhibited by scoparone and spirodiclofen + scoparone; conversely, P450 was activated in spirodiclofen-exposed mites. Importantly, RNAi-mediated silencing of the TcCYP388A1 gene markedly increased the susceptibility of spider mites to spirodiclofen, scoparone and spirodiclofen + scoparone, and in vitro, the recombinant TcCYP388A1 protein could metabolize spirodiclofen. Molecular docking and functional analyses further indicated that R117, which is highly conserved in Arachnoidea species, may be a vital specific binding site for scoparone in the mite TcCYP388A1 protein. This binding site was subsequently confirmed using mutagenesis data, which revealed that this binding site was the sole site selected by scoparone in spider mites over mammalian or fly CYP388A1. These results indicate that the synergistic effects of scoparone and spirodiclofen on mites occurs through the inhibition of P450 activity, thus reducing spirodiclofen metabolism. The synergistic effect of this potent natural product on the detoxification enzyme-targeted activity of commercial acaricides may offer a sustainable strategy for pest mite resistance management. © 2024 Society of Chemical Industry.

Phosphate deficiency increases plant susceptibility to Botrytis cinerea infection by inducing the abscisic acid pathway.

Plants have evolved finely regulated defense systems to counter biotic and abiotic threats. In the natural environment, plants are typically challenged by simultaneous stresses and, amid such conditions, crosstalk between the activated signaling pathways becomes evident, ultimately altering the outcome of the defense response. As an example of combined biotic and abiotic stresses, inorganic phosphate (Pi) deficiency, common in natural and agricultural environments, can occur along with attack by the fungus Botrytis cinerea, a devastating necrotrophic generalist pathogen responsible for massive crop losses. We report that Pi deficiency in Arabidopsis thaliana increases its susceptibility to infection by B. cinerea by influencing the early stages of pathogen infection, namely spore adhesion and germination on the leaf surface. Remarkably, Pi-deficient plants are more susceptible to B. cinerea despite displaying the appropriate activation of the jasmonic acid and ethylene signaling pathways, as well as producing secondary defense metabolites and reactive oxygen species. Conversely, the callose deposition in response to B. cinerea infection is compromised under Pi-deficient conditions. The levels of abscisic acid (ABA) are increased in Pi-deficient plants, and the heightened susceptibility to B. cinerea observed under Pi deficiency can be reverted by blocking ABA biosynthesis. Furthermore, high level of leaf ABA induced by overexpression of NCED6 in Pi-sufficient plants also resulted in greater susceptibility to B. cinerea infection associated with increased spore adhesion and germination, and reduced callose deposition. Our findings reveal a link between the enhanced accumulation of ABA induced by Pi deficiency and an increased sensitivity to B. cinerea infection.

ELONGATED HYPOCOTYL 5 interacts with HISTONE DEACETYLASE 9 to suppress glucosinolate biosynthesis in Arabidopsis.

Glucosinolates (GSLs) are defensive secondary metabolites produced by Brassicaceae species in response to abiotic and biotic stresses. The biosynthesis of GSL compounds and the expression of GSL-related genes are highly modulated by endogenous signals (i.e., circadian clocks) and environmental cues, such as temperature, light, and pathogens. However, the detailed mechanism by which light signaling influences GSL metabolism remains poorly understood. In this study, we found that a light-signaling factor, ELONGATED HYPOCOTYL 5 (HY5), was involved in the regulation of GSL content under light conditions in Arabidopsis (Arabidopsis thaliana). In hy5-215 mutants, the transcript levels of GSL pathway genes were substantially upregulated compared with those in wild-type plants. The content of GSL compounds was also substantially increased in hy5-215 mutants, whereas 35S::HY5-GFP/hy5-215 transgenic lines exhibited comparable levels of GSL-related transcripts and GSL content to those in WT plants. HY5 physically interacts with HISTONE DEACETYLASE9 (HDA9) and binds to the proximal promoter region of MYB29 and IMD1 to suppress aliphatic GSL biosynthetic processes. These results demonstrate that HY5 suppresses GSL accumulation during the daytime, thus properly modulating GSL content daily in Arabidopsis plants.

A comprehensive review on host plant resistance of wonder crop, soybean (Glycine max) against whitefly (Bemisia tabaci)

Whiteflies are significant pests that adversely affect soybean yield qualitatively and quantitatively. Understanding the host plant resistance traits of soybean against whiteflies is crucial for developing resistant cultivars for sustainable management of whitefly. This review provides an overview of the defensive proteins, secondary metabolites, signalling molecules, and antioxidant systems involved in soybean's resistance mechanisms. Additionally, it discusses the genetic and molecular basis of resistance, breeding strategies, and the influence of environmental and agronomic factors.

α-Tocopherol mediates alleviation of salt stress effects in Glycine max through up-regulation of the antioxidant defense system and secondary metabolites

α-Tocopherol (αT) has been reported to overcome the adverse effects of many environmental stresses, including salinity. A pot experiment was performed to investigate the response of salt-stressed soybean plants to the foliar application using 50, 100, or 200 mg αT L–1. The stress was applied by irrigation with three different dilutions of seawater [e.g., EC = 0.23 (tap water as a control), 3.13, or 6.25 dS m–1]. The gradual increase in salinity level gradually increased net carbon dioxide (CO2) assimilation, relative growth rate, antioxidant capacity, secondary metabolites (total phenolic compounds, flavonoids, and tannins), enzymatic activities, and DNA fragmentation due to the gradual increase in lipid peroxidation as a result of an increase in hydrogen peroxide (H2O2). On the contrary, yield components (number and weight of seeds plant–1) and photosynthetic pigment (total chlorophyll and carotenoids) contents gradually decreased with increasing salinity level. However, leaf treatment with αT, especially at 200 mg αT L‒1, preserved the highest antioxidant activities (antioxidant capacity, secondary metabolites, and enzymes), which were associated with the preservation of soybean yield and leaf pigments. These positive results occurred due to the reduction in lipid peroxidation as a result of a significant decrease in the level of H2O2. Therefore, our results recommend the use of 200 mg αT L–1 as a commercial formula for soybeans grown under saline irrigation of no more than 6.25 dS m–1.

Comparative Transcriptome Analysis Provides Insights into Fruit Trichome Development in Peach

Fruit pubescence (trichome) is an important characteristic and is controlled by a single dominant gene (G/g), resulting in peaches and nectarines. The length and/or density of fruit fuzz varies greatly among different peach cultivars. However, little is known about fruit trichome development in peaches. In this study, significant differences in fruit trichome length and density were identified between ‘XT1’ and its bud mutation ‘BM’, showing much higher values for ‘BM’. Comparative transcriptome analysis was performed, and 987 differentially expressed genes (DEGs) were identified, which were confirmed by qRT-PCR. GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses showed that genes involved in defense response, secondary metabolites and plant hormone signal transduction may also be related to the development of peach fruit trichomes. By integrating other transcriptome data, we finally determined 47 DEGs that might participate in peach trichome development, including five plant-hormone-related genes. The promoter analysis showed that one abscisic-acid-related gene, Prupe.6G072400 (abscisic acid 8′-hydroxylase 2), and one auxin-related gene, Prupe.3G074900 (auxin-responsive protein IAA1), have obvious differences in the cis-acting elements of the promoters between ‘XT1’ and ‘BM’. The results of this study will provide a valuable resource illustrating the mechanism of fruit trichome development in peaches and benefit future genomic research.

Development of defense system and secondary metabolites of Korla fragrant pear during Alternaria alternata infection

Development of defense system and secondary metabolites of Korla fragrant pear during Alternaria alternata infection

The Effect of some secondary metabolites on food consumption and pupal parameters of male and female Malacosoma neustria L. (Lepidoptera: Lasiocampidae) larvae

Plants produce secondary metabolites for defense against herbivorous insects. In this study, the effects of different concentrations of quinine, nicotine, and tannic acid on food consumption and pupal parameters of the larva of a severe pest, Malacosoma neustria L. (Lepidoptera: Lasiocampidae), were investigated in 2007. Artificial diets containing 0.125%, 0.25%, and 0.5% concentrations of quinine or nicotine were prepared. In addition, diets containing 1.25%, 2.5%, and 5% tannin and a control diet without secondary metabolite were prepared. The feeding experiments revealed that the food consumption and pupal parameters of male and female larvae were different, and all parameters of female individuals were higher than those of male larvae. It has been determined that tannins cause more reductions in food consumption and pupal parameters than alkaloids in male and female individuals. We observed an increase in male larvae's pupal mass with increased concentration of nicotine to 0.5%. Nicotine did not cause a decrease in pupal parameters of larvae compared to quinine. In addition, all parameters of female individuals decreased with the addition of secondary metabolite. Although food consumption in alkaloid-containing diets was less than in the control group, there was a positive relationship between food consumption and pupal lipid and protein content. However, quinine had a more significant effect on triggering protein storage than nicotine. In diets containing tannins, more lipids were stored. A decrease was observed in the food consumption and pupal parameters of all individuals in the tannin-containing diets compared to the other diets.

Evidence that Ophiostomatoid Fungal Symbionts of Mountain Pine Beetle Do Not Play a Role in Overcoming Lodgepole Pine Defenses During Mass Attack.

Mountain pine beetle (MPB; Dendroctonus ponderosae Hopkins) is a devastating forest insect pest that has killed millions of hectares of pines in western North America over the past two decades. Like other bark beetles, MPB vectors ophiostomatoid fungal species, some of which are pathogenic to host pine species. The phytopathogenicity of these fungal symbionts has sparked considerable debate regarding their role in facilitating MPB attack success. We tested the hypothesis that MPB ophiostomatoid fungal associates like Grosmannia clavigera (Robinson-Jeffrey and Davidson) Zipfel, de Beer and Wingfield contribute to overwhelming host defenses during MPB mass attack. We compared responses of mature lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) trees growing in natural stands that were mass attacked by MPB with those inoculated with G. clavigera by examining host defense hormones, secondary metabolites, and gene expression profiles. The jasmonate and ethylene signatures of necrotrophic pathogen-triggered response were identified in G. clavigera-inoculated trees, but only the jasmonate signature of a herbivore-triggered response was measured in MPB-attacked trees. Several G. clavigera-induced changes in pine phenolic metabolite profiles and phenolic biosynthesis gene expression patterns were absent in MPB-attacked pines. These findings indicate that ophiostomatoid fungi like G. clavigera are not a major factor in overwhelming host defenses during MPB mass attack. Instead, fungal pathogenicity likely is more important in aiding MPB colonization and development within the host tree. Phenolics appear to play a larger role in the host response to G. clavigera than to MPB, although phenolics may also influence MPB feeding and behavior. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Comparative analysis of defensive secondary metabolites in wild teosinte and cultivated maize under flooding and herbivory stress.

Climate change is driving an alarming increase in the frequency and intensity of abiotic and biotic stress factors, negatively impacting plant development and agricultural productivity. To survive, plants respond by inducing changes in below and aboveground metabolism with concomitant alterations in defensive secondary metabolites. While plant responses to the isolated stresses of flooding and insect herbivory have been extensively studied, much less is known about their response in combination. Wild relatives of cultivated plants with robust stress tolerance traits provide an excellent system for comparing how diverse plant species respond to combinatorial stress, and provide insight into potential germplasms for stress-tolerant hybrids. In this study, we compared the below and aboveground changes in the secondary metabolites of maize (Zea mays) and a flood-tolerant wild relative Nicaraguan teosinte (Zea nicaraguensis) in response to flooding, insect herbivory, and their combination. Root tissue was analyzed for changes in belowground metabolism. Leaf total phenolic content and headspace volatile organic compound emission were analyzed for changes in aboveground secondary metabolism. Results revealed significant differences in the root metabolome profiles of teosinte and maize. Notably, the accumulation of the flavonoids apigenin, naringenin, and luteolin during flooding and herbivory differentiated teosinte from maize. Aboveground, terpenes, including trans-α-bergamotene and (E)-4,8-dimethylnona-1,3,7-triene, shaped compositional differences in their volatile profiles between flooding, herbivory, and their combination. Taken together, these results suggest teosinte may be more tolerant than maize due to dynamic metabolic changes during flooding and herbivory that help relieve stress and influence plant-insect interactions.