Physicochemical space of synthetic and natural pesticides – a meta-analysis

The first commercial use of synthetic pesticides for crop protection dates back to the 1940s, followed by a fast spreading of their use and the development of a large number of compounds. In contrast to synthetic pesticides that are nowadays designed with the help of artificial intelligence that includes computational science and combinatorial chemistry, natural pesticides are the results of long evolutionary processes involving specific host-pathogens, predator-prey and competitor interactions. For these reasons, natural pesticides are often more specific and less harmful to the environment. Natural pesticides are very diverse and can be found in various living organisms. In the present study, we investigated differences in the physicochemical space occupied by synthetic and natural pesticides. In this respect, we measured the mean and breadth of synthetic and natural pesticides, as well as the overlap between these groups in a reduced physicochemical space derived from a set of 44 physicochemical variables. We showed that physicochemical space strongly differs between synthetic and natural pesticides and could be determined with 93-100% certainty, a result comparable to differences observed in drugs. Importantly, the physicochemical space occupied by synthetic pesticides was 2.6 fold smaller than the one of natural pesticides and toxicity potential was lower in the latter. In conclusion, our work showed that the design of commercialized synthetic pesticides is underexploiting the possible physicochemical space of known natural pesticides, likely due to specific constraints. Such limitations should trigger the development of efficient natural pesticides avoiding as much as possible detrimental effects on non-target organism

Polyphenolic profile and stilbene content of Albanian “Kallmet” monovarietal wine

Aim: The aim of this work was to characterize the phenolic content of wines from the most promising autochthonous red grape variety in Albania, the Kallmet. Methods and results: To make this first survey, 16 commercial monovarietal Kallmet wines were analyzed with special attention to proanthocyanidin (condensed tannins), anthocyanin and stilbene composition. The average content of total proanthocyanidins in these wines was 3877 mgL-1 and the anthocyanin content averaged 242 mgL-1. The mean degree of polymerization (mDP) varied from 8 subunits in young wine to 31 subunits in 6-year-old wine, with a mean value of 14.5 subunits. The total free anthocyanin content ranged from 85 mgL-1 in old wine to 609 mgL-1 in young wine, with a mean value of 242.5 mgL-1. Trans-piceid was the most abundant stilbene (11 mgL-1), followed by trans-resveratrol (1.8 mgL-1). It was evidenced that cis-forms of resveratrol and piceid presented a lower content than their trans-forms. The ratio between piceid (glycoside form) and resveratrol (aglycone form) was 8.2, showing a similar stilbene pattern as in Mediterranean wines. Conclusions: Kallmet wines show proanthocyanidin polymerization characteristics and stilbene profiles very similar to red wines deriving from other varieties grown under warm climates. Significance and impact of the study: In spite of the strong interest in Kallmet grape, there is still a need for detailed studies to know the range of the different components of interest found in the produced wine

The unbearable lightness of sequenced-based identification

International audienceUsing the basic GenBank local alignment search tool program (BLAST) to identify fungi collected in a recently protected beech forest at Montricher (Switzerland), the number of ITS sequences associated to the wrong taxon name appears to be around 30%, even higher than previously estimated. Such results rely on the in-depth re-examination of BLAST results for the most interesting species that were collected, viz. first records for Switzerland, rare or patrimonial species and problematic species (when BLAST top scores were equally high for different species), all belonging to Agaricomycotina. This paper dissects for the first time a number of sequence-based identifications, thereby showing in every detail-particularly to the user community of taxonomic information-why sequence-based identification in the context of a fungal inventory can easily go wrong. Our first conclusion is that in-depth examination of BLAST results is too time consuming to be considered as a routine approach for future inventories: we spent two months on verification of approx. 20 identifications. Apart from the fact that poor taxon coverage in public depositories remains the principal impediment for successful species identification, it can be deplored that even very recent fungal sequence deposits in GenBank involve an uncomfortably high number of misidentifications or errors with associated metadata. While checking the original publications associated with top score sequences for the few examples that were here reexamined , a positive consequence is that we uncovered over 80 type sequences that were not annotated as types in GenBank. Advantages and pitfalls of sequence-based identification are discussed, particularly in the light of undertaking fungal inventories. Recommendations are made to avoid or reduce some of the major problems with sequence-based identification. Nevertheless, the prospects for a more reliable sequence-based identification of fungi remain quite dim, unless authors are ready to check and update the metadata associated with previously deposited sequences in their publications

Investigations on the role of cuticular wax in resistance to powdery mildew in grapevine

Cuticular wax on the plant epidermis inhibits or enhances prepenetration events of powdery mildew (Erysiphe necator Schwein). We examined the role of cuticular leaf and berry waxes as a resistance mechanism in four grapevine genotypes (Italia x Mercan-174, Gurcu, Isabella, A-zer KarasA +/-) resistant to powdery mildew after natural infection and inoculation. To understand cuticular wax properties, we determined the amount of wax and antifungal effects of thin layer chromatography (TLC) fractions from cuticular leaf and berry waxes, then assessed the chemical composition of fractions with different antifungal activities using gas chromatography/mass spectrometry (GC/MS). Susceptible genotypes Cabernet Sauvignon and Italia were used for comparison. Resistant and sensitive genotypes did not differ significantly in the total amount of wax on leaves and berries; however, 27 fatty acids, 26 alkanes, 6 terpenes, 4 indole derivatives and 4 ketones, and 3 amides, 3 phenols and 3 steroids were detected in fractions with high antifungal activity (ae75% inhibition of germination) in leaf and/or berry cuticular waxes of resistant genotypes only. These compounds may be evaluated as markers for powdery mildew resistance during genotype selection in a grapevine breeding program.Namik Kemal UniversityNamik Kemal University [NKUBAP.00.24.AR.14.26]The authors acknowledge the Research Fund of Namik Kemal University (Project Number NKUBAP.00.24.AR.14.26) for their support, Central Research Laboratory (NABILTEM-NKU) for using GC/MS. The authors are also grateful to Martha Rowe (University of Nebraska-Lincoln) for improving the language and for useful remarks

Metabolite induction via microorganism co-culture: A potential way to enhance chemical diversity for drug discovery

Microorganisms have a long track record as important sources of novel bioactive natural products, particularly in the field of drug discovery. While microbes have been shown to biosynthesize a wide array of molecules, recent advances in genome sequencing have revealed that such organisms have the potential to yield even more structurally diverse secondary metabolites. Thus, many microbial gene clusters may be silent under standard laboratory growth conditions. In the last ten years, several methods have been developed to aid in the activation of these cryptic biosynthetic pathways. In addition to the techniques that demand prior knowledge of the genome sequences of the studied microorganisms, several genome sequence-independent tools have been developed. One of these approaches is microorganism co-culture, involving the cultivation of two or more microorganisms in the same confined environment. Microorganism co-culture is inspired by the natural microbe communities that are omnipresent in nature. Within these communities, microbes interact through signaling or defense molecules. Such compounds, produced dynamically, are of potential interest as new leads for drug discovery. Microorganism co-culture can be achieved in either solid or liquid media and has recently been used increasingly extensively to study natural interactions and discover new bioactive metabolites. Because of the complexity of microbial extracts, advanced analytical methods (e.g., mass spectrometry methods and metabolomics) are key for the successful detection and identification of co-culture-induced metabolites. This review focuses on co-culture studies that aim to increase the diversity of metabolites obtained from microbes. The various strategies are summarized with a special emphasis on the multiple methods of performing co-culture experiments. The analytical approaches for studying these interaction phenomena are discussed, and the chemical diversity and biological activity observed among the induced metabolites are described

Isothiocyanate Derivatives of Glucosinolates as Efficient Natural Fungicides

Fungal pathogens on crops account for losses that exceed US$200 billion annually. At present, chemical fungicides are widely used in the agricultural industry. Many of these products have a detrimental effect on human and animal health and are consequently forbidden postharvest, especially in Europe. Despite efforts to develop natural crop protection, very few have been commercialized. We explored the physicochemical characteristics of (i) glucosinolate derivatives from the present study and previously published papers in the light of their known biological roles and (ii) fungitoxic glucosinolate derivatives compared with natural and chemical fungicides. We found that 13 out of 31 tested natural and semisynthetic isothiocyanates are efficient fungicides against widespread species of plant pathogens alone and in a synergistic manner. Interestingly, physicochemical characteristics of fungitoxic glucosinolate derivatives differ from those showing no activities or known for their insecticidal or insect-attractive properties. The comparison of physicochemical characteristics of natural and semisynthetic fungitoxic glucosinolate derivatives with other fungicides (natural, semisynthetic, and synthetic) revealed that isothiocyanate glucosinolate derivatives clustered with nonglucosinolate derivatives plant fungicides as well as with some synthetic ones. Most of the fungicides show high bioaccumulation potential and lipophilic properties that most likely allow them to go through membranes.[Graphic: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license

Protease inhibitors decrease the resistance of Vitaceae to Plasmopara viticola

Plasmopara viticola must successfully infect susceptible grapevine cultivars to complete its biological cycle. In resistant grapevine varieties, P. viticola is blocked by the activation of defense mechanisms; these defense mechanisms produce hypersensitive reactions, which are related to programmed cell death. In animals, programmed cell death is dependent on caspase activities. In plants, different caspase-like proteases assume the same functions. To examine the roles of caspase-like proteases in P. viticola-grapevine interactions, three varieties of grapevine with different levels of P. viticola resistance were chosen. These grapevine varieties were treated with either PMSF, a serine protease inhibitor, or E-64, a cysteine protease inhibitor. The development of the pathogen was followed microscopically, and the plant defense reactions were estimated through stilbene quantification. Both protease inhibitor treatments increased the infection rate in the resistant and immune varieties, diminished the production of toxic stilbenes and changed the level of the plants' susceptibility to the pathogen. In particular, after either protease treatment, the cultivar that was originally immune became resistant (hyphae and haustoria were observed), the resistant cultivar reached the level of a susceptible cultivar (sporulation was observed) and the susceptible cultivar became more sensitive (P. viticola colonized the entirety of the leaf mesophyll). © 2012 Elsevier Masson SAS.We gratefully acknowledge the Juana de Vega Foundation (Spain) for its financial support.Peer Reviewe