Volatile emission and biosynthesis in endophytic fungi colonizing black poplar leaves.
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ABSTRACT:
SUBMITTER: Walther C
PROVIDER: S-EPMC8313976 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Herbivory is well known to trigger increased emission of volatile organic compounds (VOCs) from plants, but we know little about the responses of mature trees. We measured the volatiles emitted by leaves of old-growth black poplar (Populus nigra) trees after experimental damage by gypsy moth (Lymantria dispar) caterpillars in a floodplain forest, and studied the effect of herbivory on the transcript abundance of two genes involved in the biosynthesis of VOCs, and the accumulation of defence phytohormones. Herbivory significantly increased volatile emission from the experimentally damaged foliage, but not from adjacent undamaged leaves in the damaged branches (i.e., no systemic response). Methylbutyraldoximes, 4,8-dimethyl-1,3,7-nonatriene (DMNT), (Z)-3-hexenol and (E)-?-ocimene, amongst other compounds, were found to be important in distinguishing the blend of herbivore-damaged vs. undamaged leaves. Herbivory also increased expression of PnTPS3 (described here for the first time) and PnCYP79D6-v4 genes at the damaged sites, these genes encode for an (E)-?-ocimene synthase and a P450 enzyme involved in aldoxime formation, respectively, demonstrating de novo biosynthesis of the volatiles produced. Herbivore-damaged leaves had significantly higher levels of jasmonic acid and its conjugate (-)-jasmonic acid-isoleucine. This study shows that mature trees in the field have a robust response to herbivory, producing induced volatiles at the damaged sites even after previous natural herbivory and under changing environmental conditions, however, further studies are needed to establish whether the observed absence of systemic responses is typical of mature poplar trees or if specific conditions are required for their induction.
| S-EPMC6531464 | biostudies-literature
Project description:Poplar (Populus spp.) trees are widely distributed and play an important role in ecological communities and in forestry. Moreover, by releasing high amounts of isoprene, these trees impact global atmospheric chemistry. One of the most devastating diseases for poplar is leaf rust, caused by fungi of the genus Melampsora. Despite the wide distribution of these biotrophic pathogens, very little is known about their effects on isoprene biosynthesis and emission. We therefore infected black poplar (P. nigra) trees with the rust fungus M. larici-populina and monitored isoprene emission and other physiological parameters over the course of infection to determine the underlying mechanisms. We found an immediate and persistent decrease in photosynthesis during infection, presumably caused by decreased stomatal conductance mediated by increased ABA levels. At the same time, isoprene emission remained stable during the time course of infection, consistent with the stability of its biosynthesis. There was no detectable change in the levels of intermediates or gene transcripts of the methylerythritol 4-phosphate (MEP) pathway in infected compared to control leaves. Rust infection thus does not affect isoprene emission, but may still influence the atmosphere via decreased fixation of CO2.
| S-EPMC6277707 | biostudies-literature
Project description:During a long-term, large network study of the ecology of plant endophytes in native habitats, various nematodes have been found. Two poplar species, Populus angustifolia (narrowleaf cottonwood) and Populus trichocarpa (black cottonwood), are important ecological and genomic models now used in ongoing plant-pathogen-endophyte interaction studies. In this study, two different aphelenchid nematodes within surface-sterilized healthy leaves of these two Populus spp. in northwestern North America were discovered. Nematodes were identified and characterized microscopically and molecularly with 28S ribosomal RNA (rRNA) and 18S rRNA molecular markers. From P. angustifolia, Aphelenchoides saprophilus was inferred to be closest to another population of A. saprophilus among sequenced taxa in the 18S tree. From P. trichocarpa, Laimaphelenchus heidelbergi had a 28S sequence only 1 bp different from that of a Portuguese population, and 1 bp different from the original Australian type population. The 28S and 18S rRNA trees of Aphelenchoides and Laimaphelenchus species indicated L. heidelbergi failed to cluster with three other Laimaphelenchus species, including the type species of the genus. Therefore, we support a conservative definition of the genus Laimaphelenchus, and consider these populations to belong to Aphelenchoides, amended as Aphelenchoides heidelbergi n. comb. This is the first report of these nematode species from within aboveground leaves. The presence of these fungal-feeding nematodes can affect the balance of endophytic fungi, which are important determinants of plant health.
| S-EPMC4859615 | biostudies-literature
Project description:We investigated the diversity of the foliar endophytes of Korean ginseng. Endophytic fungi were isolated from healthy leaves of mountain-cultivated ginseng (MCG) and field-cultivated ginseng (FCG) at 4 sites in Chungbuk Province. A total of 24 species of fungal endophytes were identified using molecular approaches. Additionally, the diversity of these endophytic fungi was compared between MCG and FCG. The major isolated endophytes were Edenia gomezpompae and Gibberella moniliformis in the MCG and FCG samples, respectively. The results suggest that ginseng endophytes have different community structures in different environments, and this understanding may prove useful in ginseng cultivation.
| S-EPMC4112230 | biostudies-literature
Project description:There have been two hundred reports that endophytic fungi produce Taxol®, but its production yield is often rather low. Although considerable efforts have been made to increase Taxol/taxanes production in fungi by manipulating cocultures, mutagenesis, genome shuffles, and gene overexpression, little is known about the molecular signatures of Taxol biosynthesis and its regulation. It is known that some fungi have orthologs of the Taxol biosynthetic pathway, but the overall architecture of this pathway is unknown. A biosynthetic putative gene homology approach, combined with genomics and transcriptomics analysis, revealed that a few genes for metabolite residues may be located on dispensable chromosomes. This review explores a number of crucial topics (i) finding biosynthetic pathway genes using precursors, elicitors, and inhibitors; (ii) orthologs of the Taxol biosynthetic pathway for rate-limiting genes/enzymes; and (iii) genomics and transcriptomics can be used to accurately predict biosynthetic putative genes and regulators. This provides promising targets for future genetic engineering approaches to produce fungal Taxol and precursors. KEY POINTS: • A recent trend in predicting Taxol biosynthetic pathway from endophytic fungi. • Understanding the Taxol biosynthetic pathway and related enzymes in fungi. • The genetic evidence and formation of taxane from endophytic fungi.
| S-EPMC10560151 | biostudies-literature
Project description:Switchgrass (Panicum virgatum L.), a perennial C4 grass, represents an important species in natural and anthropogenic grasslands of North America. Its resilience to abiotic and biotic stress has made switchgrass a preferred bioenergy crop. However, little is known about the mechanisms of resistance of switchgrass against pathogens and herbivores. Volatile compounds such as terpenes have important activities in plant direct and indirect defense. Here, we show that switchgrass leaves emit blends of monoterpenes and sesquiterpenes upon feeding by the generalist insect herbivore Spodoptera frugiperda (fall armyworm) and in a systemic response to the treatment of roots with defense hormones. Belowground application of methyl jasmonate also induced the release of volatile terpenes from roots. To correlate the emission of terpenes with the expression and activity of their corresponding biosynthetic genes, we identified a gene family of 44 monoterpene and sesquiterpene synthases (mono- and sesqui-TPSs) of the type-a, type-b, type-g, and type-e subfamilies, of which 32 TPSs were found to be functionally active in vitro. The TPS genes are distributed over the K and N subgenomes with clusters occurring on several chromosomes. Synteny analysis revealed syntenic networks for approximately 30-40% of the switchgrass TPS genes in the genomes of Panicum hallii, Setaria italica, and Sorghum bicolor, suggesting shared TPS ancestry in the common progenitor of these grass lineages. Eighteen switchgrass TPS genes were substantially induced upon insect and hormone treatment and the enzymatic products of nine of these genes correlated with compounds of the induced volatile blends. In accordance with the emission of volatiles, TPS gene expression was induced systemically in response to belowground treatment, whereas this response was not observed upon aboveground feeding of S. frugiperda. Our results demonstrate complex above and belowground responses of induced volatile terpene metabolism in switchgrass and provide a framework for more detailed investigations of the function of terpenes in stress resistance in this monocot crop.
| S-EPMC6761604 | biostudies-literature
Project description:Plant species are known to harbor large number of endophytes, which stays in plant tissues as symbionts. These endophytes secrete large array of bioactive compounds that have potency against certain diseases with no side effects. We have collected leaf samples of the Moringa oleifera plant from the Pakistan Forest Institute, Khyber Pakhtunkhwa, Pakistan for the isolation of beneficial endophytes. The strains isolated from the leaves of M. oleifera were coded with MOL and tested for antimicrobial, antifungal, germicidal, phytotoxic, insecticidal, cytotoxic, and anti-inflammatory activities. The isolates, MOL1, MOL16, MOL19, and MOL21, possessed antibacterial activity against Staphylococcus aureus, whereas MOL7 inhibited 55% of the growth of Escherichia coli. MOL3 inhibited the growth of E. coli, S. aureus, and Pseudomonas aeruginosa. The strains, MOL1 and MOL7, showed antifungal activity against Candida albicans and Saccharomyces cerevisiae, while the strains, MOL11 and MOL17, showed activity against Verticillium chlamydosporium. The isolates, MOL3, MOL7, MOL9, MOL15, MOL17, MOL18, and MOL19, inhibited the growth of Lemna minor (duckweed) at 100 μg/ml. MOL2 exhibited strong activity in the brine shrimp assay, while MOL1, MOL2, MOL5, MOL6, MOL12, MOL17, MOL19, and MOL20 showed insecticidal, and MOL3 demonstrated larvicidal and antileishmanial activity. The isolated potent endophytes were identified as Aspergillus, Penicillium, Fusarium, Tricoderma, Rhizoctonia, Mucor, Alternaria, Pestalotiopsis, Acremonium, and Cladosporium through morphological and microscopic characteristics of the colonies.
| S-EPMC9779999 | biostudies-literature
Project description:In several terrestrial ecosystems such as grasslands, plants live together with various root-colonizing dark septate endophytes (DSEs), fungi that are relatively frequent colonizers of healthy belowground tissues of plants in these environments. They are important members of the plant microbiota and may have various effects on plant survival under different stress conditions; however, their general functions in relation to plants and the greater ecosystem remain elusive. Although an increasing number of studies has been published focusing on DSEs in Asian grasslands, our knowledge is limited. Especially in Mongolia, where the steppe region represents a significant area, information is not available on these root colonizers. In this study, we aimed to characterize DSEs of a common dominant gramineous plant species, Stipa krylovii in a semiarid grassland of Mongolia. Root samples were collected in a natural steppe and were processed for isolation of fungal endophytes. For molecular identification of the isolates, the internal transcribed spacer (ITS) region of the nrDNA was obtained for all the isolates investigated; furthermore, the partial translation elongation factor 1-α (TEF) gene and large subunit (LSU) and small subunit (SSU) of rDNA were also amplified and sequenced in case of representative isolates. In vitro tests were used to examine the rough symbiotic nature of the fungi, and root colonization was visualized. A majority of the 135 isolates examined in detail was found to belong to several orders of Ascomycota (110 isolates) and some to Basidiomycota (25 isolates). A significant number of the isolates represented presumably novel taxa, and dominant similarities of the lineages have been found with relatively frequent and known grass root endophytes of semiarid areas in other geographic regions. These endophytes included Periconia macrospinosa, Microdochium bolley, and Darksidea, the genus of which comprised one fourth of the isolates. We found numerous lineages, which have been detected not only from Asian steppe ecosystems, but also from prairies in North America and sandy grasslands in Europe. Therefore, our results strengthen the hypothesized worldwide presence of a common and dominant core group of a DSE community in arid and semiarid grasslands.
| S-EPMC6861457 | biostudies-literature
Project description:BackgroundAs a response to caterpillar feeding, poplar releases a complex mixture of volatiles which comprises several classes of compounds. Poplar volatiles have been reported to function as signals in plant-insect interactions and intra- and inter-plant communication. Although the volatile blend is dominated by mono- and sesquiterpenes, there is much to be learned about their formation in poplar.ResultsHere we report the terpene synthase (TPS) gene family of western balsam poplar (Populus trichocarpa) consisting of 38 members. Eleven TPS genes (PtTPS5-15) could be isolated from gypsy moth (Lymantria dispar)-damaged P. trichocarpa leaves and heterologous expression in Escherichia coli revealed TPS activity for ten of the encoded enzymes. Analysis of TPS transcript abundance in herbivore-damaged leaves and undamaged control leaves showed that seven of the genes, PtTPS6, PtTPS7, PtTPS9, PtTPS10, PtTPS12, PtTPS13 and PtTPS15, were significantly upregulated after herbivory. Gypsy moth-feeding on individual leaves of P. trichocarpa trees resulted in induced volatile emission from damaged leaves, but not from undamaged adjacent leaves. Moreover, the concentration of jasmonic acid and its isoleucine conjugates as well as PtTPS6 gene expression were exclusively increased in the damaged leaves, suggesting that no systemic induction occurred within the tree.ConclusionsOur data indicate that the formation of herbivore-induced volatile terpenes in P. trichocarpa is mainly regulated by transcript accumulation of multiple TPS genes and is likely mediated by jasmonates. The specific local emission of volatiles from herbivore-damaged leaves might help herbivore enemies to find their hosts or prey in the tree canopy.
| S-EPMC4197230 | biostudies-literature
Project description:In the light of the fast growing several applications of selenium nanoparticles (SeNPs) in different industrial and agricultural sectors, this paper was conducted to explore the suitability of endophytic fungi as nano-factories for SeNPs. Thus, 75 fungal isolates were recovered from plant tissues and tested for their efficacy to biosynthesize SeNPs. Four promising strains were found able to synthesis SeNPs with different characteristics and identified. These strains were Aspergillus quadrilineatus isolated from the twigs of Ricinus communis, Aspergillus ochraceus isolated from the leaves of Ricinus communis, Aspergillus terreus isolated from the twigs of Azadirachta indica, and Fusarium equiseti isolated from the twigs of Hibiscus rose-sinensis. The synthesized SeNPs were characterized by several techniques viz., UV-Vis, X-ray diffraction, Dynamic light scattering analyses, High resolution transmission electron microscopy, and Fourier transform infrared spectroscopy, to study their crystalline structure, particle sized distribution, and morphology. Furthermore, the in vitro antimicrobial and antioxidant activities were evaluated. SeNPs synthesized by the four strains showed potent antifungal and antibacterial potentials against different human and phyto- pathogens. Moreover, SeNPs synthesized by the respective strains showed promising antioxidant power with IC50 values of 198.32, 151.23, 100.31, and 91.52 µg mL- 1. To the best of our knowledge, this is the first study on the use of endophytic fungi for SeNPs' biosynthesis. The presented research recommends the use of endophytic fungi as facile one-pot production bio-factories of SeNPs with promising characteristics.
| S-EPMC9177918 | biostudies-literature