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Anthracnose is a major production constraint for st. john’s wort (Hypericum perforatum L.) caused by the fungus Colletotrichum gloeosporioides (Penz.). A greenhouse screening method based on mortality was developed to eliminate accessions susceptible to anthracnose in the early stage of breeding for resistant cultivars. The mortality of 22 accessions of st. john’s wort artificially inoculated with a strain of C. gloeosporioides was highly correlated between three greenhouse experiments (r = 0.799 to 0.923), even when done at two different places. The response of the greenhouse screening was equally highly correlated to the mortality in the field tested at two sites naturally infested with C. gloeosporioides (r = 0.700 to 0.865) but less well correlated with the mortality at a third field site (r = 0.495 to 0.672). Yield of st. john’s wort was highly correlated with mortality (r = –0.747 to –0.846) at all three field sites, but a significant interaction between accession and site was observed. Therefore, an improvement of anthracnose resistance of st. john’s wort should be based on a greenhouse screening of seedlings followed by multiple-site field testing of adult plants.

Sweet sagewort, also known as sweet wormwood (Artemisia annua L.), contains essential oil and other natural products. The objective of this study was to evaluate the effect of eight different distillation times (DTs; 1.25 minutes, 2.5 minutes, 5 minutes, 10 minutes, 20 minutes, 40 minutes, 80 minutes, and 160 minutes) on A. annua essential oil and its antioxidant capacity. Highest essential oil yield was achieved at 160-minute DT. The concentration of camphor (8.7% to 50% in the oil) was highest at the shorter DT and reached a minimum at 160-minute DT. The concentration of borneol showed a similar trend as the concentration of camphor. The concentrations of some constituents in the oil were highest at 2.5-minute DT (alpha-pinene and camphene), at 10 minutes (paracymene), at 20 minutes (beta-chamigrene and gamma-himachalene), at 80 minutes [transmuurola-4(15),5-diene and spathulenol], at 80- to 160-minute DT (caryophylene oxide and cis-cadin-4-en-ol), or at 160-minute DT (beta-caryophyllene, transbeta-farnesene, and germacrene-D). The yield of individual constituents reached maximum at 20- to 160-minute DT (camphor) at 80- to 160-minute DT [paracymene, borneol, transmuurola-4(15),5-diene, and spathulenol], or at 160-minute DT (for the rest of the oil constituents). DT can be used to attain A. annua essential oil with differential and possibly targeted specific chemical profile. The highest antioxidant capacity of the oil was obtained at 20-minute DT and the lowest from the oil in the 5-minute DT. This study suggests that literature reports on essential oil content and composition of A. annua could be compared only if the essential oil was extracted at similar DTs. Therefore, DT must be reported when reporting data on essential oil content and composition of A. annua.

Artemisia annua is used as a source of artemisinin, a potent therapeutic agent used for the treatment of infectious diseases, chiefly malaria. However, the low concentration (from 0.01 to 1.4% of dried leaf matter) of artemisinin in the plant obtained with the traditional cropping system makes it a relatively expensive drug, especially in developing countries. Considering that artemisinin and silicon (Si) are both stored in A. annua glandular trichomes, and that Si accumulation has never been investigated, this study aimed to look into Si effects on A. annua trichome artemisinin concentration, and whether leaf infusion from Si-treated A. annua plants is able to control Toxoplasma gondii growth. T. gondii is the etiologic agent of toxoplasmosis, a zoonotic parasitic disease whose traditional treatment shows significant side effects. The experimental design consisted of A. annua seedlings randomly planted in soil treated with different doses of calcium/magnesium silicate (0, 200, 400, 800, and 1600 kg ha-1). Analysis of foliar macronutrients showed significant increases of nitrogen content only at the highest dose of silicate. Foliar micronutrients, Si concentrations, and plant height were not affected by any of the silicate doses. However, the dose of 400 kg ha-1 of silicate increased the trichome size, which in turn raised artemisinin concentration in leaves and the infusion. In contrast, the 800 and 1600 kg ha-1 doses dramatically decreased artemisinin concentration. HeLa cell treatment with the infusion of A. annua grown in soil treated with 400 kg ha-1 of silicate decreased parasite proliferation in a dose-dependent manner when the treatment was carried out after or along with T. gondii infection. However, this effect was similar to A. annua grown in soil without silicate treatment. Thus, it can be concluded that, even though Si applied to the soil at 400 kg ha-1 has a positive effect on the A. annua glandular trichome size and the artemisinin concentration, this outcome cannot be directly associated with the efficiency of A. annua infusion on T. gondii growth, suggesting that other components from A. annua leaves could be acting in synergy with artemisinin.

A distinct sobemovirus was isolated from diseased Artemisia annua plants grown in experimental culture plots in Switzerland. Electron microscopy performed on extracts of leaf and root samples of a diseased A. annua plant revealed icosahedral-30 nm viral particles. The complete nucleotide sequence of the viral genome was determined. The single positive-strand RNA of 4138 nt encodes four open reading frames with an organization similar to that described for sobemoviruses. Phylogenetic analysis revealed a close relationship to ryegrass mottle virus. The virus was efficiently acquired by healthy A. annua from contaminated soil samples. "Artemisia virus A" is tentatively proposed as a name for this new candidate member of the unassigned genus Sobemovirus.

SUMMARY The acreage of St. John's wort (Hypericum perforatum L.), a drug-yielding plant used for its antidepressive properties, considerably increased in Europe over the last few years. In Switzerland, this acreage regularly suffers anthracnose, a disease caused by the Colletotrichum gloeosporioides (Penz.) fungus. Our tests were designed to compare 21 wild and 3 commercial varieties on 3 sites with distinct soil climates. This article emphasizes a high genotype variation for this species. We were able to select a genotype that is in agronomical terms more satisfactory than the reference variety (Topas). It is dieback tolerant, high-yielding, easy to harvest and should subsequently prove more cost-effective. It blooms early and is thus particularly suitable for growth at high altitude. Finally, its flavonoid and hypericin contents are pharma-ceutically promising. It has also been noted that anthracnose is not so virulent at high altitudes and the soil type has an influence on flower production but does no...

Artemisinin, the endoperoxide sesquiterpene lactone produced by the Chinese medicinal herb Artemisia annua, is very difficult to synthesise. Moreover, its production by mean of cell, tissue or organ cultures is very low. Presently, only its extraction from cultivated plants is viable. A large variation in artemisinin content has been observed in the leaves of plants from different origins. The genetic basis of this variation has been assessed and evidence for a quantitative inheritance of the artemisinin concentration presented. Additive genetic components were predominant, resulting in a high narrow-sense heritability estimate. Thus, goods results can be expected from mass selection for the breeding of lines of Artemisia annua rich in artemisinin. Yet, dominance variance is also present in the total genetic variability, indicating that crosses between selected genotypes should generate progenies with particularly high artemisinin content. As a matter of fact, selection and crossing, in wild populations, of genotypes with high artemisinin concentration resulted in hybrid lines containing up to 1.4 % artemisinin (on dry leaves basis).

In the framework of a breeding programme, the analysis of hundreds of oregano samples to determine their essential oil content (EOC) is time-consuming and expensive in terms of labour. Therefore developing a new method that is rapid, accurate and less expensive to use would be an asset to breeders. The aim of the present study was to develop a method based on near-inrared (NIR) spectroscopy to determine the EOC of oregano dried powder. Two spectroscopic approaches were compared, the first using a hand-held NIR device and the second a Fourier transform (FT) NIR spectrometer.Hand-held NIR (1000-1800 nm) measurements and partial least squares regression allowed the determination of EOC with R² and SEP values of 0.58 and 0.81 mL per 100 g dry matter (DM) respectively. Measurements with FT-NIR (1000-2500 nm) allowed the determination of EOC with R² and SEP values of 0.91 and 0.68 mL per 100 g DM respectively. RPD, RER and RPIQ values for the model implemented with FT-NIR data were satisfactory for screening application, while those obtained with hand-held NIR data were below the level required to consider the model as enough accurate for screening application.The FT-NIR approach allowed the development of an accurate model for EOC prediction. Although the hand-held NIR approach is promising, it needs additional development before it can be used in practice.