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• Grapevine trunk diseases have devastating consequences on vineyards worldwide. European wild grapevines (Vitis vinifera subs. sylvestris) from the last viable population in Germany along the Rhine river showed variable degrees of resistance against Neofusicoccum parvum (strain Bt-67), a fungus associated with Botryosphaeriaceae-related dieback. • Representative genotypes from different subclades of this population were mapped with respect to their ability to induce wood necrosis, as well as their defence responses in a controlled inoculation system. • The difference in colonization patterns could be confirmed by cryo-scanning electron microscopy, while there was no relationship between vessel diameter and infection success. Resistant lines accumulated more stilbenes, that were in addition significantly partitioned to nonglycosylated viniferin trimers. By contrast, the susceptible genotypes accumulated less stilbenes with a significantly higher proportion of glycosylated piceid. • We suggest a model in which in the resistant genotypes phenylpropanoid metabolism is channelled rapidly and specifically to the bioactive stilbenes. Our study specifies a resistant chemotype against grapevines trunk diseases and paves a way to breed for resistance against grapevine Botryosphaeriaceae-related dieback.

Ear rot is a serious disease that affects maize yield and grain quality worldwide. The mycotoxins are often hazardous to humans and livestock. In samples collected in China between 2009 and 2014, Fusarium verticillioides and F. graminearum species complex were the dominant fungi causing ear rot. According to the TEF-1α gene sequence, F. graminearum species complex in China included three independent species: F. graminearum, F. meridionale, and F. boothii. The key gene FUM1 responsible for the biosynthesis of fumonisin was detected in all 82 F. verticillioides isolates. Among these, 57 isolates mainly produced fumonisin B1, ranging from 2.52 to 18,416.44 µg/g for each gram of dry hyphal weight, in vitro. Three different toxigenic chemotypes were detected among 78 F. graminearum species complex: 15-ADON, NIV and 15-ADON+NIV. Sixty and 16 isolates represented the 15-ADON and NIV chemotypes, respectively; two isolates carried both 15-ADON and NIV-producing segments. All the isolates carrying NIV-specific segment were F. meridionale. The in vitro production of 15-ADON, 3-ADON, DON, and ZEN varied from 5.43 to 81,539.49; 6.04 to 19,590.61; 13.35 to 19,795.33; and 1.77 to 430.24 µg/g of dry hyphal weight, respectively. Altogether, our present data demonstrate potential main mycotoxin production of dominant pathogenic Fusarium in China.

Ocimum species represent commercially important medicinal and aromatic plants. The essential oil biosynthesized by Ocimum species is enriched with specialized metabolites specifically, terpenoids and phenylpropanoids. Interestingly, various Ocimum species are known to exhibit diverse chemical profiles, and this chemical diversity has been at the center of many studies to identify commercially important chemotypes. Here, we present various chemotypes from the Ocimum species and emphasize trends, implications, and strategies for the quality and yield improvement of essential oil. Globally, many Ocimum species have been analyzed for their essential oil composition in over 50 countries. Asia represents the highest number of chemotypes, followed by Africa, South America, and Europe. Ocimum basilicum L. has been the most widespread and well-studied species, followed by O . gratissimum L., O . tenuiflorum L., O . canum Sims, O . americanum and O . kilimandscharicum Gürke. Moreover, various molecular reasons, benefits, adverse health effects and mechanisms behind this vast chemodiversity have been discussed. Different strategies of plant breeding, metabolic engineering, transgenic, and tissue-culture, along with anatomical modifications, are surveyed to enhance specific chemotypic profiles and essential oil yield in numerous Ocimum species. Consequently, chemical characterization of the essential oil obtained from Ocimum species has become indispensable for its proper utilization . The present chemodiversity knowledge from Ocimum species will help to exploit various applications in the industrial, agriculture, biopharmaceutical, and food sectors.

Background Here, we investigated the underlying transcriptional-level evidence behind phytochemical differences between two metabolically extreme genotypes of Thymus daenensis. The genotypes ‘Zagheh-11’ (thymol/carvacrol type, poor in essential oil [EO] [2.9%] but rich in triterpenic acids) and ‘Malayer-21’ (thymol type and rich in EO [3.8%]) were selected from an ongoing breeding program and then clonally propagated for further experimental use. Materials and methods GC-MS, GC-FID, and HPLC-PDA were utilized to monitor the fluctuation of secondary metabolites at four phenological stages (vegetative, bud burst, early, and full-flowering stages). The highest phytochemical divergence was observed at early flowering stage. Both genotypes were subjected to mRNA sequencing (approximately 100 million paired reads) at the aforementioned stage. The expression patterns of four key genes involved in the biosynthesis of terpenoids were also validated using qRT-PCR. Results Carvacrol content in ‘Zagheh-11’ (26.13%) was approximately 23 times higher than ‘Malayer-21’ (1.12%). Reciprocally, about 10% higher thymol was found in ‘Malayer-21’ (62.15%). Moreover, the concentrations of three major triterpenic acids in ‘Zagheh-11’ were approximately as twice as those found in ‘Malayer-21’. Transcriptome analysis revealed a total of 1840 unigenes that were differentially expressed, including terpene synthases, cytochrome P450, and terpenoid backbone genes. Several differentially expressed transcription factors (such as MYB , bZIP , HB - HD - ZIP , and WRKY families) were also identified. These results suggest that an active cytosolic mevalonate (MVA) pathway may be linked to higher levels of sesquiterpenes, triterpenic acids, and carvacrol in ‘Zagheh-11’. The chloroplastic pathway of methyl erythritol phosphate (MEP) may have also contributed to a higher accumulation of thymol in Malayer-21. Indeed, ‘Zagheh-11’ showed higher expression of certain genes ( HMGR , CYP71D180 , β-amyrin 28-monooxygenase , and sesquiterpene synthases ) in the MVA pathway, while some genes in the MEP pathway (including DXR, ispG , and γ- terpinene synthase ) were distinctly expressed in Malayer-21. Future efforts in metabolic engineering of MVA/MEP pathways may benefit from these findings to produce increased levels of desired secondary metabolites at commercial scale.

Citral chemotypes Cinnamomum camphora (C. camphora) and Cinnamomum bodinieri (C. bodinieri) are promising industrial plants that contain abundant citral. For a more in-depth study, their significant biological effect, the chemical composition and antioxidant capacity of essential oils of citral-rich chemotype C. camphora and C. bodinieri (EOCC) were determined in the present study. The EOCC yield, obtained by hydro-distillation and analyzed by gas chromatography–mass spectrometry (GC-MS), ranged from 1.45–2.64%. Forty components more than 0.1% were identified and represented, mainly by a high content of neral (28.6–39.2%), geranial (31.8–54.1%), Z-isocitral (1.8–3.2%), E-isocitral (3.2–4.7%), geraniol (1.3–2.6%) and caryophyllene (0.6–2.4%). The antioxidant properties of EOCC were estimated by DPPH, ABTS and FRAP methods. As our results indicated, the antioxidant activity was significantly correlated to oxygenated monoterpenes. The variety of C. bodinieri (N7) presented the best antioxidant profile, given its highest inhibition of DPPH radical (IC50 = 6.887 ± 0.151 mg/mL) and ABTS radical scavenging activity (IC50 = 19.08 ± 0.02 mg/mL). To the best of our knowledge, more than 88% citral of C. bodinieri was investigated and the antioxidant properties described for the first time. Considering high essential oil yield, rich citral content and high antioxidant activity, the N7 variety will be a good candidate for pharmaceutical and cosmetic development of an improved variety.

Searching for new bio-based herbicides is crucial for decreasing chemical pollution, protecting the environment, and sustaining biodiversity. Origanum vulgare is considered a promising source of essential oil with herbicidal effect. The mode of action is not known. The present study focused on (1) comparison of phytotoxic activity of Origanum vulgare EO on monocot (Triticum aestivum and Hordeum vulgare) and dicot species (Lepidium sativum and Sinapis alba); (2) and evaluating other antimicrobial biological activities against phytopatogen bacteria (Clavibacter michiganensis, Pseudomonas syringae pv. phaseolicola, Pseudomonas savastanoi, and Xanthomonas campestris); antifungal activity against Monilinia fructicola, Aspergillus niger, Penicillium expansum, and Botrytis cinerea; cytotoxic activity and antioxidant activity. According to the GC/MS analyses, the EO belongs to the thymol chemotype O. vulgare with its high content of thymol (76%). Germination of all four species was not influenced by EO. The phytotoxic effect was statistically significant in the monocot species, while in the dicot species the opposite was observed—a stimulation effect, which was also statistically significant. Strong biological activity of O. vulgare EO was noted on all phytopatogen bacteria and fungi in the highest dose. Cytotoxic activity showed an IC50 = 50.5 μg/mL. Antioxidant activity showed an IC50 = 106.6 μg/mL after 45 min experimental time. Based on the presented results, it is possible to conclude that thymol chemotype O. vulgare essential oil could be potentially used as a herbicide with selective effects on monocot plant species.

In addition to delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), other phytocannabinoids, such as cannabigerol (CBG) and cannabichromene (CBC), also have beneficial effects on human health. A high content of CBG is found in plants with the B genotype, whereas CBC is independent of the allelic chemotype locus B. In basic research models such as mice or rats, CBG has demonstrated anticancer properties, particularly against breast cancer. CBG has shown anti-inflammatory effects on murine colitis and on inflammatory bowel disease as well as stimulatory effects on the feeding behaviors of mice. It has also exhibited inhibition of aldose reductase, which is known to cause an accumulation of sorbitol and increase glucose levels in the blood, which may lead to diabetes. Cannabinoid CBC has also shown anti-inflammatory effects and reduced hypermobility in the gut and has displayed potential effect on adult neural stem progenitor cells. CBC also exerts modest analgesic properties in rodents, as well as anti-fungal, anti-bacterial, pro-apoptotic, and anti-proliferative effects in tumor cells.

The chemical compositions of eleven wild species of aromatic and medicinal plants indigenous to Algeria, including Thymus, Mentha, Rosmarinus, Lavandula, and Eucalyptus, were analyzed. The identification of the chemical composition of each oil was conducted using GC-FID and GC-MS capillary gas chromatography. The study investigated the chemical variability of the essential oils based on several parameters. These included the impact of the vegetative cycle on oil composition, variations among subspecies of the same species, variations among species within the same genus, the influence of environmental factors on composition variations within a species, chemo typing, and the genetic factors (such as hybridization) contributing to chemical variability. The concepts of chemotaxonomy, chemotype, and chemical markers were examined to understand their limitations and emphasize the importance of regulating the use of essential oils derived from wild plants. The study advocates for an approach that involves the domestication of wild plants and screening their chemical compositions according to more specific standards for each commercially available oil. Lastly, the nutritional implications and the variability of nutritional impact based on the chemical composition of the essential oils will be discussed.

Main conclusionTranscription factors MhMYB1 and MhMYB2 correlate with monoterpenoid biosynthesis pathway in l-menthol chemotype of Mentha haplocalyx Briq, which could affect the contents of ( −)-menthol and ( −)-menthone.Mentha haplocalyx Briq., a plant with traditional medicinal and edible uses, is renowned for its rich essential oil content. The distinct functional activities and aromatic flavors of mint essential oils arise from various chemotypes. While the biosynthetic pathways of the main monoterpenes in mint are well understood, the regulatory mechanisms governing different chemotypes remain inadequately explored. In this investigation, we identified and cloned two transcription factor genes from the M. haplocalyx MYB family, namely MhMYB1 (PP236792) and MhMYB2 (PP236793), previously identified by our research group. Bioinformatics analysis revealed that MhMYB1 possesses two conserved MYB domains, while MhMYB2 contains a conserved SANT domain. Yeast one-hybrid (Y1H) analysis results demonstrated that both MhMYB1 and MhMYB2 interacted with the promoter regions of MhMD and MhPR, critical enzymes in the monoterpenoid biosynthesis pathway of M. haplocalyx. Subsequent virus-induced gene silencing (VIGS) of MhMYB1 and MhMYB2 led to a significant reduction (P < 0.01) in the relative expression levels of MhMD and MhPR genes in the VIGS groups of M. haplocalyx. In addition, there was a noteworthy decrease (P < 0.05) in the contents of ( −)-menthol and ( −)-menthone in the essential oil of M. haplocalyx. These findings suggest that MhMYB1 and MhMYB2 transcription factors play a positive regulatory role in ( −)-menthol biosynthesis, consequently influencing the essential oil composition in the l-menthol chemotype of M. haplocalyx. This study serves as a pivotal foundation for unraveling the regulatory mechanisms governing monoterpenoid biosynthesis in different chemotypes of M. haplocalyx.