Synthesis Of Secondary Metabolites Research Articles

Genome sequence of Bacillus velezensis LZN01 inhibiting Fusarium oxysporum f. sp. niveum and producing myriocin

The bacterial strain LZN01 is a potential biocontrol agent that produces myriocin and inhibits the growth of Fusarium oxysporum f. sp. niveum (Fon). To characterize strain LZN01, the Illumina HiSeq + PacBio sequencing platform was used to sequence its genome. Unicycler software was used to perform genome assembly and antiSMASH to predict gene clusters responsible for secondary metabolite biosynthesis. The genome comprises 3973236 bp and has a 46.52% G + C content. Genome annotation predicts 4031 coding DNA sequences (CDSs), 27 rRNAs and 86 tRNAs. Strain LZN01 was identified as Bacillus velezensis based on phylogenomic analysis. We identified 14 gene clusters associated with the synthesis of antimicrobial secondary metabolites, including surfactin, fengycin, bacillibactin and bacilysin, among others. There are also genes associated with induced systemic resistance and plant growth promotion, such as biofilm formation, swarming motility, root colonisation, phosphate solubilisation, phytohormone production, acetoin and 2,3-butanediol synthesis. Many genes are associated with plant–bacteria interactions, including pectinase and galactosidase genes. We inferred that the genes epsN, capD, dagK, glk and manA are associated with myriocin biosynthesis. Overall, our data provide a valuable reference for further studies of the biocontrol mechanisms of strain LZN01 as a promising agent for application in agricultural practice.

Potential pathways and genes expressed in Chrysanthemum in response to early fusarium oxysporum infection

BackgroundChrysanthemum Fusarium wilt is a common fungal disease caused by Fusarium oxysporum, which causes continuous cropping obstacles and huge losses to the chrysanthemum industry. The defense mechanism of chrysanthemum against F. oxysporum remains unclear, especially during the early stages of the disease. Therefore, in the present study, we analyzed chrysanthemum ‘Jinba’ samples inoculated with F. oxysporum at 0, 3, and 72 h using RNA-seq.ResultsThe results revealed that 7985 differentially expressed genes (DEGs) were co-expressed at 3 and 72 h after F. oxysporum infection. We analyzed the identified DEGs using Kyoto Encyclopedia of Genes and Genomes and Gene Ontology. The DEGs were primarily enriched in “Plant pathogen interaction”, “MAPK signaling pathway”, “Starch and sucrose metabolism”, and “Biosynthesis of secondary metabolites”. Genes related to the synthesis of secondary metabolites were upregulated in chrysanthemum early during the inoculation period. Furthermore, peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase enzymes were consistently produced to accumulate large amounts of phenolic compounds to resist F. oxysporum infection. Additionally, genes related to the proline metabolic pathway were upregulated, and proline levels accumulated within 72 h, regulating osmotic balance in chrysanthemum. Notably, the soluble sugar content in chrysanthemum decreased early during the inoculation period; we speculate that this is a self-protective mechanism of chrysanthemums for inhibiting fungal reproduction by reducing the sugar content in vivo. In the meantime, we screened for transcription factors that respond to F. oxysporum at an early stage and analyzed the relationship between WRKY and DEGs in the “Plant-pathogen interaction” pathway. We screened a key WRKY as a research target for subsequent experiments.ConclusionThis study revealed the relevant physiological responses and gene expression changes in chrysanthemum in response to F. oxysporum infection, and provided a relevant candidate gene pool for subsequent studies on chrysanthemum Fusarium wilt.

Novel mechanisms for the synthesis of important secondary metabolites in Ginkgo biloba seed revealed by multi-omics data.

Although the detailed biosynthetic mechanism is still unclear, the unique secondary metabolites of Ginkgo biloba, including ginkgolic acids (GAs) and terpene trilactones, have attracted increasing attention for their potent medicinal, physiological and biochemical properties. In particular, GAs have shown great potential in the fields of antibacterial and insecticidal activities, making it urgent to elucidate their biosynthetic mechanism. In this study, we systematically revealed the landscape of metabolic-transcriptional regulation across continuous growth stages of G. biloba seeds (GBS) based on multi-omics mining and experimental verification, and successfully identified all major types of GAs and terpene trilactones along with more than a thousand kinds of other metabolites. The phenological changes and the essential gene families associated with these unique metabolites were analyzed in detail, and several potential regulatory factors were successfully identified based on co-expression association analysis. In addition, we unexpectedly found the close relationship between large introns and the biosynthesis of these secondary metabolites. These genes with large introns related to the synthesis of secondary metabolites showed higher gene expression and expression stability in different tissues or growth stages. Our results may provide a new perspective for the study of the regulatory mechanism of these unique secondary metabolites in GBS.

Heterogeneity changes of active bacterial community on cigar filler leaves after fermentation based on metagenome.

Microorganisms play an important role in cigar fermentation. To further explore the dynamic changes of bacterial community composition, the changes of surface bacterial diversity of cigar filler leaves were investigated in the present study by high-throughput sequencing technology. It was found that the surface bacterial richness was declined after fermentation, and the dominant microorganisms on the surface of cigar filler leaves evolved from Pseudomonas spp. and Sphingomonas spp. before fermentation to Staphylococcus spp. after fermentation. The chemical composition and sensory quality evaluation of cigar filler leaves were closely related to the changes of surface bacterial community. The changes of the dominant surface bacterial community led to the differences of metabolic functions, among which the metabolic pathways such as the synthesis of secondary metabolites, carbon metabolism, and amino acid biosynthesis were significantly different. The results provide a basis for clarifying the roles of bacteria in fermentation of cigar filler leaves.

Secondary metabolites from endophytic fungi: Production, methods of analysis, and diverse pharmaceutical potential.

The synthesis of secondary metabolites is a constantly functioning metabolic pathway in all living systems. Secondary metabolites can be broken down into numerous classes, including alkaloids, coumarins, flavonoids, lignans, saponins, terpenes, quinones, xanthones, and others. However, animals lack the routes of synthesis of these compounds, while plants, fungi, and bacteria all synthesize them. The primary function of bioactive metabolites (BM) synthesized from endophytic fungi (EF) is to make the host plants resistant to pathogens. EF is a group of fungal communities that colonize host tissues' intracellular or intercellular spaces. EF serves as a storehouse of the above-mentioned bioactive metabolites, providing beneficial effects to their hosts. BM of EF could be promising candidates for anti-cancer, anti-malarial, anti-tuberculosis, antiviral, anti-inflammatory, etc. because EF is regarded as an unexploited and untapped source of novel BM for effective drug candidates. Due to the emergence of drug resistance, there is an urgent need to search for new bioactive compounds that combat resistance. This article summarizes the production of BM from EF, high throughput methods for analysis, and their pharmaceutical application. The emphasis is on the diversity of metabolic products from EF, yield, method of purification/characterization, and various functions/activities of EF. Discussed information led to the development of new drugs and food additives that were more effective in the treatment of disease. This review shed light on the pharmacological potential of the fungal bioactive metabolites and emphasizes to exploit them in the future for therapeutic purposes.

Стрес-протекторні та регуляторні властивості саліцилової кислоти і перспективи її використання в рослинництві

Salicylic acid (SA), as a secondary phenolic metabolite with phytohormonal activity, is an important component of the plant defense system against biotic and abiotic stresses. The scale of industrial synthesis of SA in the world is constantly growing, it is used as an intermediate for the synthesis of drugs and dyes, it is also used in cosmetology, food industry, plant biotechnology, etc. Recently, it has been considered as a promising growth-regulating agent in crop production for decreasing harmful effects of biotic and abiotic stresses in plants. Over the past two decades, numerous data have been published concerning the metabolic pathways of SA synthesis and its signaling in plant immunity. It regulates and affects various stages of plant ontogenesis and metabolism: seed germination, flowering, stomatal movements, pigment synthesis, photosynthesis and respiration, ethylene biosynthesis, thermoregulation, the activity of antioxidant enzymes, nutrient absorption, membrane integrity and functioning, nodulation in legumes, synthesis of secondary metabolites, general growth and development of plants. Numerous studies have confirmed that endogenous SA and/or its derivatives are involved in stress responses to heavy metals (HMs), hyper- and hypothermia, salinity, water deficiency, and, primarily, pathogenic infections. In parallel with fundamental studies of regulatory functions of SA and/or its derivatives, new ways of their exogenous application are constantly discovered. The use of low concentrations of exogenous SA (0.1–0.5 mM) for seed priming or foliar treatment is reported as an economically viable alternative approach for increasing plant tolerance from both economic and environmental points of view. Exogenous SA leads to an increase in endogenous SA levels that induces plant adaptive responses by changing phytohormonal status, increased synthesis of a number of secondary metabolites (alkaloids, cyanogenic glycosides, phenolics, terpenes), by increasing activity of antioxidant enzymes. One of the main advantages of using SA in crop production is the ability to reduce the dosage of pesticides and fertilizers that are potentially harmful to the environment and human health. It is also reported that the use of SA in some cases may lead to negative results – growth retardation, sterility, and yield decrease; the causes of this phenomenon are actively investigated. Further studies are necessary to clarify the mechanisms of exogenic SA action and its use on various crops in different growing conditions. This review aims to analyze the recent data on SA, crop production, and biotechnology areas where it is possible to effectively apply the SA and/or its derivatives.

Applications of Flow Chemistry in Total Synthesis of Natural Products

Abstract: A vital driving force for chemists to discover novel synthetic protocols is the improvement of more effective synthetic technologies and sustainable methodologies. This is associated with the development of innovative research that stimulates the creative reevaluating of known conceptions. Currently, these robust methodologies, as well as green synthetic procedures, have been designed for the total synthesis of secondary metabolites. Flow chemistry and flow photochemistry have emerged as powerful tools to promote valuable transformations in the total synthesis of natural products as key step(s). Flow chemistry development offers many merits over a traditional batch format, namely a round-bottom flask. The advantages of this green tool comprise waste minimization, simple scale-up, reduction of reaction time, safety betterment as, well as energy and cost efficiency. Flow chemistry comprises a fascinating prospect for the synthesis of promising organic molecules and bioactive complex natural products as it represents a suitable modern synthetic technology for the improvement of sustainable chemistry. Continuous flow chemistry is an assembly of chemical processes carried out in continuous flowing streams. Compared to conventional organic synthesis, it is a process that strengthens technology and is superior in enhancing and scaling up synthesis, accurately controlling reaction rate, and providing the desired products with maximum yields. In the past and likely in the future natural products and their analogue will continue to deliver the stimulation for drug discovery and development programs. Total synthesis of natural products is very useful to synthesize natural products in the laboratory as many secondary metabolites are available in low quantities from their sources of origin. So, this review wishes to cover the brilliant applications of flow chemistry in the total synthesis of natural products in the field of novel technological advances.

Metaproteomics profiling of the microbial communities in fermentation starters (Daqu) during multi-round production of Chinese liquor.

The special flavor and fragrance of Chinese liquor are closely related to microorganisms in the fermentation starter Daqu. The changes of microbial community can affect the stability of liquor yield and quality. In this study, we used data-independent acquisition mass spectrometry (DIA-MS) for cohort study of the microbial communities of a total of 42 Daqu samples in six production cycles at different times of a year. The DIA MS data were searched against a protein database constructed by metagenomic sequencing. The microbial composition and its changes across production cycles were revealed. Functional analysis of the differential proteins was carried out and the metabolic pathways related to the differential proteins were explored. These metabolic pathways were related to the saccharification process in liquor fermentation and the synthesis of secondary metabolites to form the unique flavor and aroma in the Chinese liquor. We expect that the metaproteome profiling of Daqu from different production cycles will serve as a guide for the control of fermentation process of Chinese liquor in the future.

Pengaruh Komposisi Media Hidroponik dan Konsentrasi Pupuk Cair Cucian Beras terhadap Pertumbuhan dan Hasil Tanaman Basil Merah (Ocium Basilicum L.)

Modification of the nutrient solution in the red basil plant can be done hydroponically, because it is able to stimulate the synthesis of secondary metabolites of the basil plant so that the plant can easily get the necessary nutrients through the addition of nutrient doses. The application of liquid organic fertilizer can help the addition of nutrients, while the use of different planting media is expected to obtain a good combination for the cultivation process. This study used rice washing water with the trademark pandanwangi and a combination of planting media between husk charcoal, sand, and bokashi. This study used a factorial complete randomized design (4x3) and repeated 3 times. The factors used are the concentration of rice laundry liquid fertilizer (P), consisting of 4 levels: (P0) : Control 0%, (P1): Rice washing liquid fertilizer concentration 25%, (P2): Rice washing liquid fertilizer concentration 50%, (P3): Rice washing liquid fertilizer concentration 75%, and substrate media composition factor (Q), consisting of 3 levels: (Q1): Husk charcoal and sand 1:1, (Q2): Husk charcoal and bokasi 1:1, (Q3): Husk charcoal, sand and bokasi 1:1:1. The observation variables in this study are plant height, number of leaves planted, leaf area, fresh weight of leaves, dry weight of leaves, fresh weight of plants, dry weight of plants and volume of roots. Based on the results of research that has been carried out, the results of the treatment obtained The interaction between the composition of the planting media and the addition of liquid fertilizer for rice laundry does not have a noticeable effect on all treatments except the root volume parameter. The composition treatment of the growing medium had an unreal effect on all treatments except plant height and leaf area with recommendations of husk charcoal:sand (1:1) for plant height and husk charcoal:bokasi (1:1) for leaf area. The treatment of adding concentration of liquid fertilizer to rice laundry has a noticeable effect on all treatments except the fresh weight of the leaves and the fresh weight of the plant with the best recommendation in applying the concentration of liquid fertilizer of rice laundry 25% perliter - 50% perliter on each plant.

Exploring the Biologically Active Metabolites Produced by Bacillus cereus for Plant Growth Promotion, Heat Stress Tolerance, and Resistance to Bacterial Soft Rot in Arabidopsis

Eight gene clusters responsible for synthesizing bioactive metabolites associated with plant growth promotion were identified in the Bacillus cereus strain D1 (BcD1) genome using the de novo whole-genome assembly method. The two largest gene clusters were responsible for synthesizing volatile organic compounds (VOCs) and encoding extracellular serine proteases. The treatment with BcD1 resulted in an increase in leaf chlorophyll content, plant size, and fresh weight in Arabidopsis seedlings. The BcD1-treated seedlings also accumulated higher levels of lignin and secondary metabolites including glucosinolates, triterpenoids, flavonoids, and phenolic compounds. Antioxidant enzyme activity and DPPH radical scavenging activity were also found to be higher in the treated seedlings as compared with the control. Seedlings pretreated with BcD1 exhibited increased tolerance to heat stress and reduced disease incidence of bacterial soft rot. RNA-seq analysis showed that BcD1 treatment activated Arabidopsis genes for diverse metabolite synthesis, including lignin and glucosinolates, and pathogenesis-related proteins such as serine protease inhibitors and defensin/PDF family proteins. The genes responsible for synthesizing indole acetic acid (IAA), abscisic acid (ABA), and jasmonic acid (JA) were expressed at higher levels, along with WRKY transcription factors involved in stress regulation and MYB54 for secondary cell wall synthesis. This study found that BcD1, a rhizobacterium producing VOCs and serine proteases, is capable of triggering the synthesis of diverse secondary metabolites and antioxidant enzymes in plants as a defense strategy against heat stress and pathogen attack.

Identification, characterization and expression analysis of the 4-coumarate-coA ligase gene family in Bletilla striata

The 4-coumarate-coA ligase (4CL) gene plays an important role in plant growth and development as well as the synthesis of secondary metabolites, but its function in Bletilla striata has not been extensively studied. Based on the former full-length transcriptome sequencing database built on suspension culture cells of B. striata (Bletilla striata), we identified 4CL gene family members and conducted secondary structure, motif, evolutionary tree, and KEGG enrichment analysis of their proteins using bioinformatics software. We also analyzed their genetic polymorphisms and expression patterns using EST-SSR and qPCR. We have confirmed the relationship between the expression of the 4CL gene and the biosynthesis of secondary metabolites in B. striata through correlation analysis. Our results indicate that 21 4CL genes were obtained from the transcriptome database, named as Bs4CL (4-coumarate-coa ligase of Bletilla striata) 1–21 gene. They were subcellularly located in peroxisome, and the secondary structure was mainly comprised of random coil and alpha helix. KEGG enrichment analysis showed that Bs4CL gene family members were mainly involved in lipid metabolism, alpha-linoleic metabolism, amino acid metabolism, phenylpropanoid biosynthesis, and other secondary metabolites. According to EST-SSR detection, we found that Bs4CL genes showed genetic polymorphism in local varieties of B. striata. q-PCR analysis showed that the expression of Bs4CL genes was tissue-specific in different tissue. Through the correlation analysis, we found that these genes play important roles in the synthesis of Coelonin, Dactylorhin A, and Militarine. These results indicate that Bs4CL gene family is involved in growth development and biosynthesis of secondary metabolites in B. striata.

ECOLOGICAL AND HYGIENIC ASSESSMENT OF QUALITY FLOWER OF TANACETUM VULGARE AGRO- AND URBANBIOCENOSES OF THE VORONEZH REGION

An important and little-researched aspect of the effect of human economic activity on medicinal plants is that in response to an increase in anthropo-genic load, additional synthesis of secondary metabolites, especially flavonoids, is induced, which play an important role in adapting plants to changing conditions. The purpose of the study was to study the accumulation of flavonoids and phenol carboxylic acids in the flowers of Tanacetum vulgare, col-lected in various agricultural and urbobiogeocenoses of the Voronezh region from the point of view of anthropogenic impact. As part of the study, 51 samples of Tanacetum vulgare flowers determined the content of heavy metals and arsenic and the sum of flavonoids and phenol carboxylic acids in terms of luteolin. By comparing the data on the content of heavy metals in the upper soil layers of the region and the content of these elements in the flowers of Tanacetum vulgare, it can be argued that there are significant physiological barriers that prevent the accumulation of ecotoxicants in the generative organs of the plant, which is especially noticeable for elements such as lead, mercury, arsenic, cadmium, cobalt and chromium. It turned out that ordinary pyjma is able to selectively concentrate copper and zinc. It was revealed that in the flowers of Tanacetum vulgare collected in agrobi-ogeocenoses and urbocenoses, the content of flavonoids and phenolcarboxylic acids is higher than in samples from protected areas, which is ex-plained by the fact that the key enzyme for the synthesis of flavonoids – phenylalaninammiacliase – has a pronounced stress inducibility. Under condi-tions of excessive toxic influence of pollutants, it is also possible to suppress the antioxidant system of plants.

Endophytic fungi mediates production of bioactive secondary metabolites via modulation of genes involved in key metabolic pathways and their contribution in different biotechnological sector.

Endophytic fungi stimulate the production of an enormous number of bioactive metabolites in medicinal plants and affect the different steps of biosynthetic pathways of these secondary metabolites. Endophytic fungi possess a number of biosynthetic gene clusters that possess genes for various enzymes, transcription factors, etc., in their genome responsible for the production of secondary metabolites. Additionally, endophytic fungi also modulate the expression of various genes responsible for the synthesis of key enzymes involved in metabolic pathways of such as HMGR, DXR, etc. involved in the production of a large number of phenolic compounds as well as regulate the expression of genes involved in the production of alkaloids and terpenoids in different plants. This review aims to provide a comprehensive overview of gene expression related to endophytes and their impact on metabolic pathways. Additionally, this review will emphasize the studies done to isolate these secondary metabolites from endophytic fungi in large quantities and assess their bioactivity. Due to ease in synthesis of secondary metabolites and their huge application in the medical industry, these bioactive metabolites are now being extracted from strains of these endophytic fungi commercially. Apart from their application in the pharmaceutical industry, most of these metabolites extracted from endophytic fungi also possess plant growth-promoting ability, bioremediation potential, novel bio control agents, sources of anti-oxidants, etc. The review will comprehensively shed a light on the biotechnological application of these fungal metabolites at the industrial level.

Bacillus velezensis SQR9 inhibition to fungal denitrification responsible for decreased N2O emissions from acidic soils

Tropical and subtropical acidic soils are hotspots of global terrestrial nitrous oxide (N2O) emissions, with N2O produced primarily through denitrification. Plant growth-promoting microbes (PGPMs) may effectively mitigate soil N2O emissions from acidic soils, achieved through differential responses of bacterial and fungal denitrification to PGPMs. To test this hypothesis, we conducted a pot experiment and the associated laboratory trials to gain the underlying insights into the PGPM Bacillus velezensis strain SQR9 effects on N2O emissions from acidic soils. SQR9 inoculation significantly reduced soil N2O emissions by 22.6–33.5 %, dependent on inoculation dose, and increased the bacterial AOB, nirK and nosZ genes abundance, facilitating the reduction of N2O to N2 in denitrification. The relative contribution of fungi to the soil denitrification rate was 58.4–77.1 %, suggesting that the N2O emissions derived mainly from fungal denitrification. The SQR9 inoculation significantly inhibited the fungal denitrification and down-regulated fungal nirK gene transcript, dependent on the SQR9 sfp gene, which was necessary for secondary metabolite synthesis. Therefore, our study provides new evidence that decreased N2O emissions from acidic soils can be due to fungal denitrification inhibited by PGPM SQR9 inoculation.

Chemical Identification of Secondary Metabolites from Rhizospheric Actinomycetes Using LC-MS Analysis: In Silico Antifungal Evaluation and Growth-Promoting Effects.

The rhizosphere is a rich source of actinomycetes which can produce several potential biologically active secondary metabolites. The principal goal for this research is to extract, purify, and characterize the bioactive secondary metabolites produced by three different strains of actinomycetes isolated from the rhizosphere of rosemary, black locust, and olive. The plant growth-promoting effect (PGPE) of the studied strains of actinomycetes on Ocimum basilicum L. (basil) and the disease-control effect on necrotic stem lesions of "black leg" caused by Fusarium tabacinum on basil were evaluated in silico. The cell-free culture filtrates from the studied actinomycetes isolates were evaluated in vitro for their antimicrobial activity against some common phytopathogens. The secondary metabolites obtained from the cell-free culture filtrates have been chemically characterized using high-resolution electrospray ionization of liquid-chromatography/mass-spectrometric detection (ESI-(HR)Orbitrap-MS). Results of the in silico trial showed that all studied isolates demonstrated PGPE on basil seedlings, improved some eco-physiological characteristics, and reduced the disease incidence of F. tabacinum. The extracted metabolites from the studied actinomycetes demonstrated antimicrobial activity in a Petri-plates assay. The chemical analysis revealed the presence of 20 different components. This research emphasizes how valuable the examined isolates are for producing bioactive compounds, indicating their putative antimicrobial activity and their potential employment as fungal biocontrol agents. In particular, the obtained results revealed the possibility of green synthesis of some important secondary metabolites, such as N-Acetyl-l-histidinol, Rhizocticin A, and Eponemycin, from actinomycetes. The bioactive metabolites may be successively used to develop novel bio-formulations for both crop protection and/or PGPE.

Ferulic acid enhanced resistance against blue mold of Malus domestica by regulating reactive oxygen species and phenylpropanoid metabolism

Postharvest decay of fruit caused by phytopathogen often causes tremendous losses during logistics. Ferulic acid is a kind of phenolic acid which has potential antimicrobial ability and initiates defense responses. This study performed to evaluate the induced resistance of ferulic acid against blue mold of apples (cv. Qiujin) as well as the mechanism involved in its action. Results suggested that 1.0 g L−1 ferulic acid remarkably reduced lesion diameter of Penicillium expansum-inoculated apples and colony diameter in vitro. The activities and gene expressions of catalase, superoxide dismutase, peroxidase, dehydroascorbate reductase, glutathione reductase, monodehydroascorbate reductase, ascorbate peroxidase, and nicotinamide adenine dinucleotide phosphate oxidase were distinctly improved by ferulic acid immersion. Ferulic acid also promoted ascorbic acid and reduced glutathione contents, whereas decreased hydrogen peroxide and malondialdehyde contents in apples. Moreover, ferulic acid enhanced the gene expressions and activities of cinnamyl alcohol dehydrogenase, 4-coumarate coenzyme A ligase, cinnamate-4-hydroxylase, and phenylalanine ammonia-lyase, resulting in caffeic acid, flavonoids, lignin, total phenolics, and p-coumaric acid accumulation in apples. Taken together, ferulic acid could activate the activities and gene expressions of the key enzymes in phenylpropanoid pathway as well as reactive oxygen species metabolism to promote the synthesis of antioxidants and secondary metabolites, thereby increasing disease resistance of apples.

Full-length transcriptome sequencing of the short-rotation woody crop Salix integra reveals a time series response to Pb stress

The short-rotation woody crop Salix integra is a low-cost, renewable feedstock that can be used in the medical and energy industry sectors. Lead (Pb) is a highly toxic, nondegradable heavy metal that accumulates in the soil, can reduce the biomass productivity of plants and threatens human health. Some genotypes of S. integra show strong tolerance to and high accumulation potential for Pb. Here, a highly tolerant S. integra clone was subjected to 0.3 mM Pb in a hydroponic system for 14 d, and roots were sampled at 9 time points. Cytotoxic substance contents and antioxidant enzyme activities were affected by Pb. Transcriptome data revealed 11039 differentially expressed transcripts (DETs); the expression levels of representative DETs were verified by RTqPCR. Weighted gene coexpression network analysis (WGCNA) and enrichment analyses showed that the response of S. integra to Pb stress could be divided into two main stages. In the early stage (mainly within 24 h), DETs were involved in the "sulfur assimilation and GSH synthesis" process and "ABC transporters" pathway. In the late stage (mainly after 3 d), the differential expression of DETs that regulate the synthesis of multiple secondary metabolites in the "phenylpropanoid biosynthesis" pathway was the main factor. Additionally, the continuous differential expression of DETs involved in the "plant hormone signal transduction" pathway suggested a complex response pattern. The results deeply revealed the Pb response pattern in S. integra driven by the coregulation of multiple pathways at different stages instead of the single Pb response pathway found in other species. This study provides new ideas for studying the Pb tolerance mechanisms of energy crops.

Trichoderma harzianum transcriptome in response to the nematode Pratylenchus brachyurus

The root-lesion nematode Pratylenchus brachyurus causes extensive damage in several crops of economic importance. Fungi of Trichoderma genus have been highlighted as biopesticide agents in the control of several plant diseases. Although it is already widely used in agriculture, there are few studies, especially at the molecular level, that evaluate T. harzianum in the control of P. brachyurus. The aim of the present study was to investigate how interaction with the nematode P. brachyurus influences gene expression of T. harzianum, by using RNA-Seq analysis. Of the 13,932 predicted genes in the T. harzianum genome, 2,922 (21%) were differentially expressed in the presence of P. brachyurus, in relation to the absence of the nematode. Among the differentially expressed genes, we found genes encoding Carbohydrate Active EnZymes (CAZy), MEROPS peptidases, and proteins related to secondary metabolite synthesis. 118 pathways were identified as related to the biosynthesis of secondary metabolites. The analysis identified 136 metabolic pathways related to these differentially expressed genes, among which we highlight: aminobenzoate degradation, xenobiotic metabolism by cytochrome P450, and sesquiterpenoid and triterpenoid biosynthesis. Our results contribute to a better understanding of the response of T. harzianum to the nematode P. bracyurus, the potential for biocontrol by this fungus.

Effects of Magnesium on Transcriptome and Physicochemical Index of Tea Leaves.

Magnesium (Mg) is one of the essential elements for the growth of tea tree and is extremely important for its development. In this study, we investigated the effect of Mg on the transcriptome and physicochemical indexes of tea leaves, and the results showed that Mg could significantly affect the gene expression of tea leaves. The results of Orthogonal Partial Least-Squares Discriminant Analysis (OPLS-DA) model analysis showed that a total of 300 key genes (Variable Importance for the Projection, VIP > 1) were screened under different concentrations of Mg treatment, among which 140 genes were up-regulated and 160 genes were down-regulated. The bubble map was used to screen the characteristic genes from the above key genes, and a total of 121 representative characteristic genes were obtained, mainly involving 9 metabolic pathways. Among them, gene expression of three metabolic pathways, including porphyrin metabolism, alpha-linolenic acid metabolism and photosynthesis, showed an increasing trend with the increase of Mg concentration, while gene expression of four metabolic pathways, including biosynthesis of secondary metabolites, anthocyanin biosynthesis, ABC transporters, pentose and glucuronate interconversions, showed a decreasing trend. The results of physiological index analysis showed that with the increase of Mg concentration, the photosynthetic physiological index, theanine and soluble sugar content of tea leaves showed an increasing trend, while the content of tea polyphenol, flavone and caffeine showed a decreasing trend. The results of TOPSIS analysis showed that the physiological indexes of tea trees most affected by Mg were chlorophyll, tea polyphenols and flavonoids, while the metabolic pathways most affected by Mg on gene expression were the metabolic pathways and biosynthesis of secondary metabolites. It can be seen that the effects of Mg on tea tree were mainly related to photosynthesis and synthesis of secondary metabolites, and Mg was beneficial for improving the photosynthetic capacity of tea tree, enhancing the accumulation of primary metabolites, and thus increasing tea yield. However, Mg was not conducive to the synthesis of secondary metabolites of tea tree and the accumulation of main quality indexes of tea leaves.

Isolation, identification and characterization of biopotential cyclic lipopeptides from Bacillus subtilis strain JN005 and its antifungal activity against rice pathogen Magnaporthe oryzae

In the present study, the cyclic lipopeptides extracted from Bacillus subtilis strain JN005 showed inhibition activity against the rice phytopathogenic fungus Magnaporthe oryzae. The isolated cyclic lipopeptides tolerated high temperature, extreme acidity, extreme alkalinity and ultraviolet radiation. The growth of the mycelium and conidia of the rice phytopathogenic fungus M. oryzae was abnormal after cyclic lipopeptide treatment. In vitro inoculation revealed that cyclic lipopeptide treatment reduced disease incidence by 17.78 ± 2.72% and 22.22 ± 3.51% in the curative and preventive groups, respectively, controlling rice leaf blast. Whole genome sequencing showed that B. subtilis strain JN005 had a circular chromosome with a length of 4,167,853 bp, an average G + C content of 43.86% and 4294 coding DNA sequences. Six gene clusters were identified based on genome analysis encoding for secondary metabolite synthesis of surfactin, fengycin, bacillibactin, bacillaene, subtilosin and bacilysin. Ultra performance liquid chromatography-quadrupole-time of flight-mass spectrometry and ultra performance liquid chromatography-quadrupole-time of flight-mass/mass spectrometry analyses of cyclic lipopeptides further demonstrated the production of surfactin and fengycin derivatives by B. subtilis strain JN005. This study provides insight into the biocontrol potential of B. subtilis strain JN005 and will facilitate its application for the management of rice blast disease caused by M. oryzae.