Exploration of essential oils as alternatives to conventional fungicides in lupin cultivation

Lupin (Lupinus L.) has the potential to become a true alternative for soybean as protein source, especially in the more temperate regions in the world. However, diseases such as anthracnose (Colletotrichum lupini), gray mold (Botrytis cinerea), and root rot or brown spot (Pleiochaeta setosa) are important threats for lupin production, leading to yield and quality losses. Although conventional fungicides offer a solution to these problems, there is a growing interest in the use of alternative (biological) treatments. In this research, the applicability of four pure plant essential oils (clove oil, juniper oil, tea tree oil, and thyme essential oil) and timbor® (a Thymus vulgaris-derived plant extract) as alternatives for synthetic fungicides towards the lupin pathogens—C. lupini, B. cinerea, and P. setosa—was investigated. The anti-fungal effect of juniper oil was limited, whereas the other oils and timbor® clearly suppressed the growth and spore germination of all fungi. The in vitro experiments revealed that thyme essential oil and timbor® were most effective to inhibit conidial germination and mycelium growth. Furthermore, the results of the pot experiments demonstrated that these Thymus-derived compounds were able to suppress P. setosa brown spot and root rot symptoms. Additional trials are necessary to evaluate the effect of these compounds under field conditions. However, based on these in vitro and pot experiments, it can be concluded that pure essential oils and Thymus-derived plant extracts are promising anti-fungal agents, having the potential to become true alternatives for conventional fungicides in lupin cultivation. To the best of our knowledge, this is the first study demonstrating the potential of plant-derived compounds to treat the main diseases affecting lupin production

Species prevalence and disease progression studies demonstrate a seasonal shift in the Alternaria population composition on potato

To assess the incidence of early blight/brown spot (EB/BS) in Flanders (Belgium), potato fields in 22 locations were monitored and scored over the duration of the growing seasons 2014 and 2015. The average disease incidence was shown to be higher in 2014 than in 2015. Soil type, rainfall and temperature were also analysed in relation to disease incidence. In 2014, potato plants grown in sandy soils had more EB/BS disease than those grown in clay or loamy soils. However, the low disease incidence in 2015 meant that differences in disease levels between soil types could not be discerned for that growing season. A windowpane analysis demonstrated that rainfall and humidity accounted for the differences in disease incidence between the two growing seasons. During the course of the survey, the species composition in leaves with symptoms was assessed using real-time PCR. Remarkably, small-spored Alternaria species, such as A. alternata and A. arborescens, rather than the more virulent A. solani were the predominant species on potato leaves throughout the growing season. As the disease progressed, the proportion of A. solani increased. In view of these results, the virulence of a collected set of Alternaria isolates was assessed by an invitro assay. Despite A. solani being more virulent than A. alternata or A. arborescens, the most abundant species isolated from potato leaves with symptoms was A. arborescens

Assessing the Belgian potato Alternaria population for sensitivity to fungicides with diverse modes of action

Early blight and brown spot, caused by respectively Alternaria solani and Alternaria alternata, can lead to severe yield losses in potato-growing areas. To date, fungicide application is the most effective measure to control the disease. However, in recent years, a reduced sensitivity towards several active ingredients has been reported. To shed light on this issue, Alternaria isolates were collected from different potato fields in Belgium during two growing seasons. Subsequently, the sensitivity of these isolates was assessed using four widely used fungicides with different modes of action. Demethylation inhibitors, quinone outside inhibitors, a dithiocarbamate and a carboxylic acid amide were included in this study. Although all fungicides reduced spore germination and vegetative growth of Alternaria species to some extent, the interspecies sensitivity was very variable. In general, A. solani was more suppressed by the fungicides compared to A. alternata. The effectiveness of the dithiocarbamate mancozeb was high, whereas the quinone outside inhibitor azoxystrobin showed a limited activity, especially towards A. alternata. Therefore, a subset of the A. alternata and A. solani isolates was tested for the presence of, respectively, the G143A substitution and the F129L substitution in the cytochrome b. The frequency of A. alternata isolates bearing the resistant G143A allele (approximately 65%) was comparable in both sampling years, although sensitivity of isolates decreased during the growing season. This finding points to a shift of the population towards resistant isolates. Both the European genotype I and American genotype II were present in the A. solani population, with genotype I being the most prevalent. None of the genotype I isolates carried the F129L substitution, whereas in 83% of the genotype II isolates this substitution was present. Our results demonstrate for the first time that the Belgian Alternaria population on potato comprises a considerable broad spectrum of isolates with different sensitivity to fungicides

The potential of Brassicaceae biofumigant crops to manage Pleiochaeta setosa in sustainable lupin cultivation

Lupin is prone to infection by Pleiochaeta setosa (Kirchn.) Hughes causing brown spot and root rot in Lupinus species. The control of these diseases is crucial to limit yield losses, but an increased public awareness and European legislative restrictions have resulted in a drastic reduction of allowed pesticides and many research groups invest in alternative biocontrol strategies. In the current study, the inhibitory effect of volatiles, released by two members of the Brassicaceae family (white mustard (Sinapis alba) and fodder radish (Raphanus sativus)), on brown spot and root rot in Lupinus species was evaluated in vitro and in vivo. The in vitro trial showed that root tissue of Brassicaceae was more effective in reducing the vegetative growth of Pleiochaeta setosa than leaf and stem tissues. Furthermore, R. sativus was more effective than S. alba. The GC-MS analysis revealed that dimethyl disulfide and dimethyl trisulfide were predominantly emitted by the tissues of both Brassicaceae. Additionally, the ground root tissue of R. sativus emitted 4-isothiocyanato-1-(methylthio)-1-butene, whereas the stem + leaf tissue emitted benzyl isothiocyanate. Benzyl isothiocyanate was also released by the ground S. alba root tissue, whereas the leaf + stem tissue emitted 3-butenyl isothiocyanate. In vitro trials with pure dimethyl disulfide and dimethyl trisulfide confirmed the antifungal effect of the volatiles released by these sulfides. For dimethyl disulfide 7.95 mg per Petri dish was necessary to (almost) completely inhibit mycelium growth, whereas for dimethyl trisulfide 1.20 mg per Petri dish was sufficient to prevent fungal growth. In addition, a trial with allyl isothiocyanate showed that for this compound even lower doses (0.50 mg per Petri dish) stopped the growth of the fungus. The results obtained with the pot trial illustrated that the amendment of Brassicaceae species significantly reduced the P. setosa infection level. Also in the field, incorporation of Brassicaceae species suppressed P. setosa. From this study, it can be concluded that Brassicaceae species are a powerful tool to manage P. setosa in lupin cultivation. However, it should be combined with other control practices since the amendment of these biofumigant crops could not completely inhibit symptom development

Aerobes and phototrophs as microbial organic fertilizers : exploring mineralization, fertilization and plant protection features

Organic fertilizers and especially microbial biomass, also known as microbial fertilizer, can enable a paradigm shift to the conventional fertilizer-to-food chain, particularly when produced on secondary resources. Microbial fertilizers are already common practice (e.g. Bloom(®) and Synagro); yet microbial fertilizer blends to align the nutrient release profile to the plant’s needs are, thus far, unexplored. Moreover, most research only focuses on direct fertilization effects without considering added value properties, such as disease prevention. This study has explored three promising types of microbial fertilizers, namely dried biomass from a consortium of aerobic heterotrophic bacteria, a microalga (Arthrospira platensis) and a purple non-sulfur bacterium (Rhodobacter sphaeroides). Mineralization and nitrification experiments showed that the nitrogen mineralization profile can be tuned to the plant’s needs by blending microbial fertilizers, without having toxic ammonium peaks. In a pot trial with perennial ryegrass (Lolium perenne L.), the performance of microbial fertilizers was similar to the reference organic fertilizer, with cumulative dry matter yields of 5.6–6.7 g per pot. This was confirmed in a pot trial with tomato (Solanum lycopersicum L.), showing an average total plant length of 90–99 cm after a growing period of 62 days for the reference organic fertilizer and the microbial fertilizers. Moreover, tomato plants artificially infected with powdery mildew (Oidium neolycopersici), a devastating disease for the horticultural industry, showed reduced disease symptoms when A. platensis was present in the growing medium. These findings strengthen the application potential of this novel class of organic fertilizers in the bioeconomy, with a promising match between nutrient mineralization and plant requirements as well as added value in crop protection

Aerobes and phototrophs as microbial organic fertilizers : exploring mineralization, fertilization and plant protection features

Organic fertilizers and especially microbial biomass, also known as microbial fertilizer, can enable a paradigm shift to the conventional fertilizer-to-food chain, particularly when produced on secondary resources. Microbial fertilizers are already common practice (e.g. Bloom (R) and Synagro); yet microbial fertilizer blends to align the nutrient release profile to the plant's needs are, thus far, unexplored. Moreover, most research only focuses on direct fertilization effects without considering added value properties, such as disease prevention. This study has explored three promising types of microbial fertilizers, namely dried biomass from a consortium of aerobic heterotrophic bacteria, a microalga (Arthrospira platensis) and a purple non-sulfur bacterium (Rhodobacter sphaeroides). Mineralization and nitrification experiments showed that the nitrogen mineralization profile can be tuned to the plant's needs by blending microbial fertilizers, without having toxic ammonium peaks. In a pot trial with perennial ryegrass (Lolium perenne L.), the performance of microbial fertilizers was similar to the reference organic fertilizer, with cumulative dry matter yields of 5.6-6.7 g per pot. This was confirmed in a pot trial with tomato (Solanum lycopersicum L.), showing an average total plant length of 90-99 cm after a growing period of 62 days for the reference organic fertilizer and the microbial fertilizers. Moreover, tomato plants artificially infected with powdery mildew (Oidium neolycopersici), a devastating disease for the horticultural industry, showed reduced disease symptoms when A. platensis was present in the growing medium. These findings strengthen the application potential of this novel class of organic fertilizers in the bioeconomy, with a promising match between nutrient mineralization and plant requirements as well as added value in crop protection

Comprehensive functional mapping scheme for non-invasive primary sensorimotor cortex mapping.

We introduce a novel multimodal scheme for primary sensorimotor hand area (SM1ha) mapping integrating multiple functional indicators from functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG). Ten right-handed healthy subjects (19-33 years; 5 females, 5 males) and four patients (24-64 years; 2 females, 2 males) suffering from space-occupying brain lesion close to the central sulcus were studied. Functional indicators of the SM1ha were obtained from block-design fMRI motor protocol, and six MEG protocols: somatosensory evoked fields to electrical median-nerve stimulation, mu-rhythm suppression (~10 and ~20 Hz), corticomuscular coherence, and corticokinematic coherence with and without finger contacts. To assess the spatial spread of the functional indicators, their coordinates were subjected to principal component analysis to produce a centered ellipsoid with axis along principal components. Five to seven functional indicators were obtained for each participant. In all participants, the ellipsoid co-localized with the anatomical SM1ha. In healthy subjects, 50-100 % of functional indicators were located within 10 mm from the center of the ellipsoid. In patients, 17-100 % of functional indicators were located within 10 mm from the center of the ellipsoid. In conclusion, the multimodal scheme proposed led to a functional mapping of SM1ha that co-localized with anatomical SM1ha in all participants. The spread of the SM1ha functional indicators in some patients with brain lesions highlights the potential benefit of the proposed multimodal approach to assess the reliability of the non-invasive SM1ha mapping.Journal ArticleSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Molecular mechanisms of ovulation: co-ordination through the cumulus complex

© The Author 2007. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: [email protected] ovulation requires that developmentally competent oocytes are released with appropriate timing from the ovarian follicle. Somatic cells of the follicle sense the ovulatory stimulus and guide resumption of meiosis and release of the oocyte, as well as structural remodelling and luteinization of the follicle. Complex intercellular communication co-ordinates critical stages of oocyte maturation and links this process with release from the follicle. To achieve these outcomes, ovulation is controlled through multiple inputs, including endocrine hormones, immune and metabolic signals, as well as intrafollicular paracrine factors from the theca, mural and cumulus granulosa cells and the oocyte itself. This review focuses on the recent advances in understanding of molecular mechanisms that commence after the gonadotrophin surge and culminate with release of the oocyte. These mechanisms include intracellular signalling, gene regulation and remodelling of tissue structure in each of the distinct ovarian compartments. Most critical ovulatory mediators exert effects through the cumulus cell complex that surrounds and connects with the oocyte. The convergence of ovulatory signals through the cumulus complex co-ordinates the key mechanistic processes that mediate and control oocyte maturation and ovulation.Darryl L. Russell and Rebecca L. Robke