Multi-omics analysis of Streptomyces djakartensis strain MEPS155 reveal a molecular response strategy combating Ceratocystis fimbriata causing sweet potato black rot.

To investigate the potential antifungal mechanisms of rhizosphere Actinobacteria against Ceratocystis fimbriata in sweet potato, a comprehensive approach combining biochemical analyses and multi-omics techniques was employed in this study. A total of 163 bacterial strains were isolated from the rhizosphere soil of sweet potato. Among them, strain MEPS155, identified as Streptomyces djakartensis, exhibited robust and consistent inhibition of C. fimbriata mycelial growth in in vitro dual culture assays, attributed to both cell-free supernatant and volatile organic compounds. Moreover, strain MEPS155 demonstrated diverse plant growth-promoting attributes, including the production of indole-3-acetic acid, 1-aminocyclopropane-1-carboxylate deaminase, phosphorus solubilization, nitrogen fixation, and enzymatic activities such as cellulase, chitinase, and protease. Notably, strain MEPS155 exhibited efficacy against various sweet potato pathogenic fungi. Following the inoculation of strain MEPS155, a significant reduction (P < 0.05) in malondialdehyde content was observed in sweet potato slices, indicating a potential protective effect. The whole genome of MEPS155 was characterized by a size of 8,030,375 bp, encompassing 7234 coding DNA sequences and 32 secondary metabolite biosynthetic gene clusters. Transcriptomic analysis revealed 1869 differentially expressed genes in the treated group that cultured with C. fimbriata, notably influencing pathways associated with porphyrin metabolism, fatty acid biosynthesis, and biosynthesis of type II polyketide products. These alterations in gene expression are hypothesized to be linked to the production of secondary metabolites contributing to the inhibition of C. fimbriata. Metabolomic analysis identified 1469 potential differently accumulated metabolites (PDAMs) when comparing MEPS155 and the control group. The up-regulated PDAMs were predominantly associated with the biosynthesis of various secondary metabolites, including vanillin, myristic acid, and protocatechuic acid, suggesting potential inhibitory effects on plant pathogenic fungi. Our study underscores the ability of strain S. djakartensis MEPS155 to inhibit C. fimbriata growth through the production of secretory enzymes or secondary metabolites. The findings contribute to a theoretical foundation for future investigations into the role of MEPS155 in postharvest black rot prevention in sweet potato.

The APSES transcription factor CfSwi6 is required for growth, cell wall integrity, and pathogenicity of Ceratocystis fimbriata.

Cell wall integrity (CWI) is crucial for the growth, development, and host invasion of pathogenic fungi. The APSES transcription factor Swi6 in fungi plays a role in mediating cell wall integrity through the mitogen-activated protein kinase (MAPK) signaling pathway. Ceratocystis fimbriata is a notorious pathogenic fungus responsible for causing black rot in sweet potatoes. In this study, an orthologous APSES transcription factor Swi6 (CfSwi6) downstream of the CWI regulatory pathway in C. fimbriata was characterized. Deletion of CfSWI6 leads to impaired hyphal development, conidiation, and compromised cell wall integrity, resulting in a significant reduction in virulence. Transcriptome analysis revealed the involvement of CfSWI6 in various pathways, including the MAPK pathway, DNA synthesis and stress response. ChIP-seq data provided predictions of potential target genes regulated by CfSwi6. Through yeast one-hybrid, we confirmed the direct binding of CfSwi6 to the promoter of the chitin synthetase gene. In summary, these findings indicated that CfSwi6 plays an important role in the growth, development, and pathogenicity of C. fimbriata. This study provides new insights into the pathogenic mechanism of C. fimbriata in sweet potato and inspires potential strategies to control sweet potato black rot.

CfErp3 regulates growth, conidiation, inducing ipomeamarone and the pathogenicity of Ceratocystis fimbriata.

The Erp3 protein, which is an important member of the p24 family, is primarily responsible for the transport of cargo from the ER to the Golgi apparatus in Saccharomyces cerevisiae. However, the function of Erp3 in plant pathogenic fungi has not been reported. In this study, we characterized the ERP3 gene in Ceratocystis fimbriata, which causes the devastating disease sweetpotato black rot. The ΔCferp3 mutants exhibited slow growth, reduced conidia production, attenuated virulence, and reduced ability to induce host to produce toxins. Further analysis revealed that CfErp3 was localized in the ER and vesicles and regulated endocytosis, cell wall integrity, and osmotic stress responses, modulated ROS levels, and the production of ipomeamarone during pathogen-host interactions. These results indicate that CfErp3 regulates C. fimbriata growth and pathogenicity as well as the production of ipomeamarone in sweetpotato by controlling endocytosis, oxidative homeostasis, and responses to cell wall and osmotic stresses.

Cultivable Endophyte Resources in Medicinal Plants and Effects on Hosts.

With the increasing demand for medicinal plants and the increasing shortage of resources, improving the quality and yield of medicinal plants and making more effective use of medicinal plants has become an urgent problem to be solved. During the growth of medicinal plants, various adversities can lead to nutrient loss and yield decline. Using traditional chemical pesticides to control the stress resistance of plants will cause serious pollution to the environment and even endanger human health. Therefore, it is necessary to find suitable pesticide substitutes from natural ingredients. As an important part of the microecology of medicinal plants, endophytes can promote the growth of medicinal plants, improve the stress tolerance of hosts, and promote the accumulation of active components of hosts. Endophytes have a more positive and direct impact on the host and can metabolize rich medicinal ingredients, so researchers pay attention to them. This paper reviews the research in the past five years, aiming to provide ideas for improving the quality of medicinal plants, developing more microbial resources, exploring more medicinal natural products, and providing help for the development of research on medicinal plants and endophytes.

Nocardioides potassii sp. nov., isolated from weathered potash tailings soil.

A Gram-positive, aerobic actinomycete, designated strain KLBMP 9356T, was isolated from weathered potash tailings soil sampled in Xuzhou, Jiangsu Province, PR China. The colonies were cream-coloured, convex and rounded. The optimal growth conditions of strain KLBMP 9356T were 1 % (w/v) NaCl, 28 °C and pH 7. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain KLBMP 9356T showed the highest similarity to Nocardioides zhouii CGMCC 1.11084T (98.9 %) and Nocardioides glacieisoli CGMCC 1.11097T (98.7 %). Results from two tree-making algorithms supported the position that strain KLBMP 9356T forms a stable clade with N. zhouii CGMCC 1.11084T and N. glacieisoli CGMCC 1.11097T. Strain KLBMP 9356T exhibited low digital DNA-DNA hybridization values with N. zhouii CGMCC 1.11084T (27.6 %) and N. glacieisoli CGMCC 1.11097T (31.4 %). The average nucleotide identity values between strain KLBMP 9356T and N. zhouii CGMCC 1.11084T and N. glacieisoli CGMCC 1.11097T were 83.8% and 85.9%, respectively. The peptidoglycan in the cell wall of the novel strain was ll-2,6-diaminopimelic acid and the predominant menaquinone was MK-8(H4). The major fatty acids (>10 %) were C17:1ω8c and C18:1ω9c. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, lyso-phospatidylglycerol and phosphatidylinositol. The genomic DNA G+C content was 71.6 mol%. Based on its morphological, chemotaxonomic and phylogenetic characteristics, strain KLBMP 9356T represents a novel species of the genus Nocardioides, for which the name Nocardioides potassii sp. nov. is proposed. The type strain is KLBMP 9356T (=CGMCC 4.7738T=NBRC 115493T).

Diversity of Endophytic Microbes in Taxus yunnanensis and Their Potential for Plant Growth Promotion and Taxane Accumulation.

Taxus spp. are ancient tree species that have survived from the Quaternary glacier period, and their metabolites, such as taxol, have been used as anticancer drugs globally. Plant-endophytic microbial interaction plays a crucial role in exerting a profound impact on host growth and secondary metabolite synthesis. In this study, high-throughput sequencing was employed to explore endophytic microbial diversity in the roots, stems, and leaves of the Taxus yunnanensis (T. yunnanensis). The analysis revealed some dominant genera of endophytic bacteria, such as Pseudomonas, Neorhizobium, Acidovorax, and Flavobacterium, with Cladosporium, Phyllosticta, Fusarium, and Codinaeopsis as prominent endophytic fungi genera. We isolated 108 endophytic bacteria and 27 endophytic fungi from roots, stems, and leaves. In vitro assays were utilized to screen for endophytic bacteria with growth-promoting capabilities, including IAA production, cellulase, siderophore production, protease and ACC deaminase activity, inorganic phosphate solubilization, and nitrogen fixation. Three promising strains, Kocuria sp. TRI2-1, Micromonospora sp. TSI4-1, and Sphingomonas sp. MG-2, were selected based on their superior growth-promotion characteristics. These strains exhibited preferable plant growth promotion when applied to Arabidopsis thaliana growth. Fermentation broths of these three strains were also found to significantly promote the accumulation of taxanes in T. yunnanensis stem cells, among which strain TSI4-1 demonstrated outstanding increase potentials, with an effective induction of taxol, baccatin III, and 10-DAB contents. After six days of treatment, the contents of these metabolites were 3.28 times, 2.23 times, and 2.17 times the initial amounts, reaching 8720, 331, and 371 ng/g of dry weight of stem cells, respectively. These findings present new insight into the industrialization of taxol production through Taxus stem cell fermentation, thereby promoting the conservation of wild Taxus resources by maximizing their potential economic benefits.

Yinghuangia soli sp. nov., isolated from soil of weathering dolomite in a karst area.

A Gram-stain-positive, aerobic actinomycete strain, designated KLBMP 8922T, was isolated from a soil sample collected from weathering dolomite crust in Guizhou Province, PR China. KLBMP 8922T showed the 16S rRNA gene similarities to Yinghuangia seranimata CCTCC AA 206006T (98.7 %), Yinghuangia catbensis VN07A0015T (98.3 %) and Yinghuangia aomiensis M24DS4T (98.2 %). The taxonomic status of this strain was investigated by using a polyphasic approach. The aerial mycelia of KLBMP 8922T formed spore chains, and spores were cylindrical with smooth surfaces. The whole-cell sugars were ribose, mannose and galactose with traces of glucose and xylose. The diagnostic amino acids of the cell wall were ll-diaminopimelic acid, alanine and glutamic acid. The predominant menaquinones were MK-9(H6) and MK-9(H8). The diagnostic phospholipids were diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositolmannoside, phosphatidylethanolamine, an unidentified phospholipid and an unidentified lipid. The major cellular fatty acids (>10 %) were iso-C15 : 0, iso-C16 : 0 and iso-C16 : 1H. The genomic DNA G+C content was 72.0 mol%. The digital DNA-DNA hybridization (dDDH) value between KLBMP 8922T and Y. seranimata CCTCC AA 206006T was 24.1 %, and the average nucleotide identity (ANI) value was 81.0 %. On the basis of a combination of morphological, chemotaxonomic and phylogenetic characteristics, strain KLBMP 8922T represents a novel species of the genus Yinghuangia for which the name Yinghuangia soli sp. nov. is proposed. The type strain was KLBMP 8922T (= CGMCC 1.19360T = NBRC 115572T).

The Role of GmSnRK1-GmNodH Module in Regulating Soybean Nodulation Capacity.

SnRK1 protein kinase plays hub roles in plant carbon and nitrogen metabolism. However, the function of SnRK1 in legume nodulation and symbiotic nitrogen fixation is still elusive. In this study, we identified GmNodH, a putative sulfotransferase, as an interacting protein of GmSnRK1 by yeast two-hybrid screen. The qRT-PCR assays indicate that GmNodH gene is highly expressed in soybean roots and could be induced by rhizobial infection and nitrate stress. Fluorescence microscopic analyses showed that GmNodH was colocalized with GsSnRK1 on plasma membrane. The physical interaction between GmNodH and GmSnRK1 was further verified by using split-luciferase complementary assay and pull-down approaches. In vitro phosphorylation assay showed that GmSnRK1 could phosphorylate GmNodH at Ser193. To dissect the function and genetic relationship of GmSnRK1 and GmNodH in soybean, we co-expressed the wild-type and mutated GmSnRK1 and GmNodH genes in soybean hairy roots and found that co-expression of GmSnRK1/GmNodH genes significantly promoted soybean nodulation rates and the expression levels of nodulation-related GmNF5α and GmNSP1 genes. Taken together, this study provides the first biological evidence that GmSnRK1 may interact with and phosphorylate GmNodH to synergistically regulate soybean nodulation.

TcMYB29a, an ABA-Responsive R2R3-MYB Transcriptional Factor, Upregulates Taxol Biosynthesis in Taxus chinensis.

Paclitaxel (Taxol), a highly modified diterpene agent mainly obtained from Taxus species, is the most widely used anticancer drug. Abscisic acid (ABA) is a well-known stress hormone that plays important roles in the secondary metabolism of plants, and it can also induce the accumulation of taxol in Taxus cell suspension cultures. However, the mechanism behind the regulation of taxol biosynthesis by ABA remains largely unknown. In previous research, a R2R3 MYB transcription factor (TF) TcMYB29a was observed to show a significant correlation with taxol biosynthesis, indicative of its potential role in the taxol biosynthesis. In this study, the TcMYB29a encoded by its gene was further characterized. An expression pattern analysis revealed that TcMYB29a was highly expressed in the needles and roots. Overexpression of TcMYB29a in Taxus chinensis cell suspension cultures led to an increased accumulation of taxol, and upregulated expression of taxol-biosynthesis-related genes, including the taxadiene synthase (TS) gene, the taxane 5α-hydroxylase (T5OH) gene, and the 3'-N-debenzoyl-2'-deoxytaxol-N-benzoyltransferase (DBTNBT) gene as compared to the controls. Chromatin immunoprecipitation (ChIP) assays, yeast one-hybrid (Y1H) assays, electrophoretic mobility shift assays (EMSAs), and dual-luciferase reporter assays verified that TcMYB29a could bind and activate the promoter of TcT5OH. Promoter sequence analysis of TcMYB29a revealed that its promoter containing an AERB site from -313 to -319 was a crucial ABA-responsive element. Subsequently, the ABA treatment assay showed that TcMYB29a was strongly upregulated at 6 h after ABA pretreatment. Furthermore, TcMYB29a was strongly suppressed at 3 h after the methyl jasmonate (MeJA) treatment and was depressed to the platform at 12 h. Taken together, these results reveal that TcMYB29a is an activator that improves the accumulation of taxol in Taxus chinensis cells through an ABA-medicated signaling pathway which is different from JA-medicated signaling pathways for the accumulation of taxol. These findings provide new insights into the potential regulatory roles of MYBs on the expression of taxol biosynthetic genes in Taxus.

The large single-copy (LSC) region functions as a highly effective and efficient molecular marker for accurate authentication of medicinal Dendrobium species.

Having great medicinal values, Dendrobium species of "Fengdou" (DSFs) are a taxonomically complex group in Dendrobium genus including many closely related and recently diverged species. Traditionally used DNA markers have been proved to be insufficient in authenticating many species of this group. Here, we investigated 101 complete plastomes from 23 DSFs, comprising 72 newly sequenced and 29 documented, which all exhibited well-conserved genomic organization and gene order. Plastome-wide comparison showed the co-occurrence of single nucleotide polymorphisms (SNPs) and insertions/deletions (indels), which can be explained by both the repeat-associated and indel-associated mutation hypotheses. Moreover, guanine-cytosine (GC) content was found to be negatively correlated with the three divergence variables (SNPs, indels and repeats), indicating that GC content may reflect the level of the local sequence divergence. Our species authentication analyses revealed that the relaxed filtering strategies of sequence alignment had no negative impact on species identification. By assessing the maximum likelihood (ML) trees inferred from different datasets, we found that the complete plastome and large single-copy (LSC) datasets both successfully identified all 23 DSFs with the maximum bootstrap values. However, owing to the high efficiency of LSC in species identification, we recommend using LSC for accurate authentication of DSFs.

Comparative Analysis of the Complete Plastomes of Apostasia wallichii and Neuwiedia singapureana (Apostasioideae) Reveals Different Evolutionary Dynamics of IR/SSC Boundary among Photosynthetic Orchids.

Apostasioideae, consists of only two genera, Apostasia and Neuwiedia, which are mainly distributed in Southeast Asia and northern Australia. The floral structure, taxonomy, biogeography, and genome variation of Apostasioideae have been intensively studied. However, detailed analyses of plastome composition and structure and comparisons with those of other orchid subfamilies have not yet been conducted. Here, the complete plastome sequences of Apostasia wallichii and Neuwiedia singapureana were sequenced and compared with 43 previously published photosynthetic orchid plastomes to characterize the plastome structure and evolution in the orchids. Unlike many orchid plastomes (e.g., Paphiopedilum and Vanilla), the plastomes of Apostasioideae contain a full set of 11 functional NADH dehydrogenase (ndh) genes. The distribution of repeat sequences and simple sequence repeat elements enhanced the view that the mutation rate of non-coding regions was higher than that of coding regions. The 10 loci-ndhA intron, matK-5'trnK, clpP-psbB, rps8-rpl14, trnT-trnL, 3'trnK-matK, clpP intron, psbK-trnK, trnS-psbC, and ndhF-rpl32-that had the highest degrees of sequence variability were identified as mutational hotspots for the Apostasia plastome. Furthermore, our results revealed that plastid genes exhibited a variable evolution rate within and among different orchid genus. Considering the diversified evolution of both coding and non-coding regions, we suggested that the plastome-wide evolution of orchid species was disproportional. Additionally, the sequences flanking the inverted repeat/small single copy (IR/SSC) junctions of photosynthetic orchid plastomes were categorized into three types according to the presence/absence of ndh genes. Different evolutionary dynamics for each of the three IR/SSC types of photosynthetic orchid plastomes were also proposed.

[Effect of Euonymus alatus on the blood glucose and hemorheology in the rat model of Type 2 diabetes mellitus with blood stagnation].

OBJECTIVE: To explore the effect of Euonymus alatus on the blood glucose and hemorheology in rat model of Type 2 diabetes mellitus with blood stagnation (DMBS). METHODS: High fat diet with streptozocin was used to establish the rat model of Type 2 diabetes mellitus, followed by the prednisolone and adrenaline muscle injection to obtain DMBS. DMBS rats were divided into a DMBS group (treated with saline gavage), an Euonymus alatus group (treated with Euonymus alatus gavage), and a glybenzoylamide group (treated with glybenzoylamide gavage).A blank group was treated with saline gavage. The experiment lasted 4 weeks, followed by the evaluation of rats' behavior, and detection of fasting blood glucose and hemorheology. RESULTS: Compared with DMBS rats, the symptoms of polydipsia and diuresis in Euonymus alatus rats were improved, with increased body weight (P<0.05), better fur and mental state, increased resistance for being caught, and reduced tongue stagnation. Compared with DMBS group, though body weight increased, resistance for being caught decreased in the glybenzoylamide group with bad fur and mental state,and tongue stagnation. As to the fasting blood glucose, there was significant difference between the Euonymus alatus group and the DMBS group (P<0.05). As to the hemorheology, including whole blood viscosity (shear rates 1,5,50, and 100 s(-1)), plasma viscosity, and hematocrit, the Euonymus alatus rats had a better efficacy than DMBS rats and glybenzoylamide rats (P<0.05 or P<0.01). CONCLUSION: Euonymus alatus can reduce the fasting blood glucose of DMBS and improve blood stagnation.