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Background: Powdery mildew, caused by Eeysiphe heraclei, seriously threatens Heracleum moellendorffii Hance. Plant secondary metabolites are essential to many activities and are necessary for defense against biotic stress. In order to clarify the functions of these metabolites in response to the pathogen, our work concentrated on the variations in the accumulation of secondary metabolites in H. moellendorffii during E. heraclei infection., Results: Following E. heraclei infection, a significant upregulation of coumarin metabolites-particularly simple coumarins and associated genes was detected by RNA-seq and UPLC-MS/MS association analysis. Identifying HmF6'H1, a Feruloyl CoA 6'-hydroxylase pivotal in the biosynthesis of the coumarin basic skeleton through ortho-hydroxylation, was a significant outcome. The cytoplasmic HmF6'H1 protein was shown to be able to catalyze the ortho-hydroxylation of p-coumaroyl-CoA and caffeoyl-CoA, resulting in the formation of umbelliferone and esculetin, respectively. Over-expression of the HmF6'H1 gene resulted in increased levels of simple coumarins, inhibiting the biosynthesis of furanocoumarins and pyranocoumarins by suppressing PT gene expression, enhancing H. moellendorffii resistance to powdery mildew., Conclusions: These results established HmF6'H1 as a resistance gene aiding H. moellendorffii in combatting E. heraclei infection, offering additional evidence of feruloyl-CoA 6'-hydroxylase role in catalyzing various types of simple coumarins. Therefore, this work contributes to our understanding of the function of simple coumarins in plants' defense against powdery mildew infection., (© 2024. The Author(s).)

As part of a search for antitubercular substances from natural sources, we screened a library of endophytic microbes (50 strains and 300 crude extracts in total) isolated from traditional Chinese medicines (TCMs) for growth inhibitory activity against Bacillus Calmette-Guérin (BCG). The crude extract of Streptomyces sp. strain Y3111, which was associated with the stems of Heracleum souliei, showed good anti-BCG activity with an MIC value of 12.5 μg/mL. Bioassay-guided isolation led to four new pluramycin-type compounds, heraclemycins A-D (1-4). Their structures were determined by different spectroscopic techniques including HRMSESI, 1D NMR, and 2D NMR. This is the first report of pluramycin analogues produced by TCM endophytic microbes as well as the first example of BCG-selective pluramycins. Heraclemycin C (3) showed selective antitubercular activity against BCG with a MIC value of 6.25 μg/mL and a potential new mode of action.

By applying a coverage-based read selection and filtration through a healthy plant dataset, and a post-assembly contig selection based on homology and linkage, genome sequence drafts were obtained for four phytoplasma strains belonging to the 16SrIII group (X disease clade), namely Vaccinium Witches' Broom phytoplasma (647 754 nt in 272 contigs), Italian Clover Phyllody phytoplasma strain MA (597 245 nt in 197 contigs), Poinsettia branch-inducing phytoplasma strain JR1 (631 440 nt in 185 contigs) and Milkweed Yellows phytoplasma (583 806 nt in 158 contigs). Despite assignment to different 16SrIII subgroups, the genomes of the four strains were similar, comprising a highly conserved core (92-98 % similar in their nucleotide sequence among each other over alignments about 500 kb in length) and a minor strain-specific component. As far as their protein complement was concerned, they did not differ significantly in their basic metabolism potential from the genomes of other wide-host-range phytoplasmas sequenced previously, but were distinct from strains of other species, as well as among each other, in genes encoding functions conceivably related to interactions with the host, such as membrane trafficking components, proteases, DNA methylases, effectors and several hypothetical proteins of unknown function, some of which are likely secreted through the Sec-dependent secretion system. The four genomes displayed a group of genes encoding hypothetical proteins with high similarity to a central domain of IcmE/DotG, a core component of the type IVB secretion system of Gram-negative Legionella spp. Conversely, genes encoding functional GroES/GroEL chaperones were not detected in any of the four drafts. The results also indicated the significant role of horizontal gene transfer among different 'Candidatus Phytoplasma' species in shaping phytoplasma genomes and promoting their diversity.

Thirty endophytic bacteria were isolated from various plant species growing near Saint-Petersburg, Russia. Based on a screening for various traits, including plant-beneficial properties and DNA fragment patterns, potential siblings were removed. The remaining isolates were taxonomically identified using 16S rDNA sequences and potential human and plant pathogens were removed. The remaining strains were tested for their ability to promote radish root growth and to protect tomato plants against tomato foot and root rot. One strain, Bacillus subtilis HC8, isolated from the giant hogweed Heracleum sosnowskyi Manden, significantly promoted plant growth and protected tomato against tomato foot and root rot. Metabolites possibly responsible for these plant-beneficial properties were identified as the hormone gibberellin and (lipo)peptide antibiotics respectively. The antibiotic properties of strain HC8 are similar to those of the commercially available plant-beneficial strain Bacillus amyloliquefaciens FZB42. However, thin layer chromatography profiles of the two strains differ. It is speculated that endophytes such as B. subtilis HC8 contribute to the fast growth of giant hogweed., (© 2011 Leiden University, Institute of Biology. Journal compilation © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.)