AGENCY PRODUCTS GOWAN ON THE TERRITORY SAFETY NEWS AND MEDIA EVENTS News Back to the list Biocontrol: fungi for plant defense 10/11/2021 How do they work and what are the main species and strains authorized in the European Union? They do not leave residues, they do not interfere with fermentation, they can be applied near the harvest and above all they are a valid tool for fighting plant diseases in organic and integrated agriculture: oomycetes , yeasts and fungi are useful biocontrol agents . After having clarified how the interaction between plant and useful microorganisms arises, it is time to put it into practice. During the fourth and fifth lessons of the "Biosolution Academy" advanced training course, the advantages and limits of use of these microorganisms were discussed through the study of the mechanisms of actionand the biology and characteristics of the most interesting genera and species authorized in the EU . Read also Where and how does the interaction between plants and microorganisms arise? The lectures were held by Ilaria Pertot , director of the Center for Agriculture and Environment of the University of Trento, by Stefano Di Marco , of the Institute of Bioeconomy of the Cnr of Bologna, by Alessandra Di Francesco of the Department of Agro-Food Sciences and Technologies of the University of Bologna and Michelina Ruocco , of the Cnr Ipsp secondary office in Portici. The mechanisms of action of fungi for biocontrol How oomycetes and fungi defend the plant from pathogens? There are four main mechanisms of action : antibiosis or direct action; resistance induction; competition for space and nutrients; hyperparasitism. Generally a species can have more than one mechanism of action, in any case it is important to know them in order to adapt them to the most effective defense strategy. Antibiosis or direct action It is a mechanism similar to that of synthetic fungicides. The microorganism produces toxins and / or lytic enzymes that inhibit the growth of the pathogen . It must be intended as a preventive treatment because it has no effect after the pathogen enters the plant tissue. However, most of the registered strains produce more enzymes than toxins because to obtain authorization it is more difficult to prove non-toxicity towards humans, the environment and animals. Resistance induction The induction of resistance allows the plant, when properly stimulated, to acquire a sort of immunity against virulent pathogens. It is a real defense system of the plant. What are the stimuli and signals that induce resistance? There is talk of elicitorsthat is, any molecular signal produced directly or indirectly by the pathogen. The interaction of these with plant cell receptors triggers a series of molecular signals capable of activating the transcription of defense genes at the nuclear level. Elicitors can be cellular fragments (chitin and chitosan constituents of the cell wall of fungi and insect exoskeleton), fragments of flagella, fatty acids, sterols, nucleic acids, proteins and glycopeptides. There are two types of resistance: acquired systemic (Sar) and induced systemic (Isr). The Sar manifests itself towards a wide spectrum of pathogens after relatively long intervals of time (one, two and more days) even in distant organs compared to those where the contact with the inductor took place. The acquisition of resistance is associated with the expression of genes encoding pathogenesis proteins (Pr) , and is mediated by salicylic acid . The PR then allow to produce antimicrobial compounds , lytic enzymes , substances that strengthen the wall , etc. Induced systemic resistance (Isr) allows for pre-activationof the latent defense mechanisms that are expressed following a subsequent attack by pathogenic microorganisms. Pre-activated plants respond faster and stronger even to very low levels of a stimulus. Taking advantage of this natural plant defense phenomenon is very innovative but will never represent the solution for plant defense. Because? First of all, plants cannot escape from the pathogen and do not have an adaptive immune system, they do not retain memory and do not produce antibodies. Furthermore, it is a phenomenon that works best for protected crops because in the field the plant is already naturally induced by many stimuli and resistance is less effective. Competition Competition for consumption ofsubstances necessary for the germination / growth of the microorganism (for example Botrytis cinerea needs sugar to germinate) and for occupying space . Also in this case we speak of preventive treatment that reduces the inoculum. Hyperparasitism It consists in the growth of a microorganism on or inside the pathogenic microorganism. This is depleted of nutrients until death. It must be said that all parasites for ecological interest will never completely eliminate the pathogen, therefore, this mechanism only leads to the reduction of the inoculum . By the same principle it is necessary that before the treatment in the field there is a certain amount of host and therefore of pathogen. Oomiceti come agenti di biocontrollo e principali prodotti autorizzati Scarsi sono stati gli studi sugli oomiceti come agenti di biocontrollo in confronto a funghi e rizobatteri, questo perché sono sempre stati ritenuti essenzialmente dei patogeni per le piante. Gli oomiceti appartengono al regno Chromista; il genere Pythium, in particolare, occupa una grande varietà di nicchie ecologiche terrestri e acquatiche, infatti comprende più di 130 specie tra saprofiti attivi, patogeni di alghe, pesci e insetti, patogeni delle piante e anche specie micoparassite. Pythium oligandrum È un oomicete micoparassita attivo contro venti generi di funghi patogeni: Botrytis, Sclerotinia, Sphaerotheca, Fusarium, Alternaria, Verticillium, Rhizoctonia e Pythium. Può ridurre dal 15 al 100% la malattia ed è un buon colonizzatore e riesce a distribuirsi abbastanza bene nelle varie nicchie ecologiche. Guarda il video di Gowan su Polyversum a base di Pythium oligandrum La resistenza nella pianta è indotta dalla produzione da parte dell'oomicete dell'oligandrina; la pianta in risposta impregna la parte cellulare di composti fenolici, forma gel di pectato di calcio negli spazi intercellulari e nel floema accumula proteine antimicrobiche. Il prodotto in commercio è il Polyversum: non ha intervallo di sicurezza (tempo di carenza) e non interferisce con la vinificazione quando utilizzato su vite, è utile per ridurre il residuo di principi attivi di sintesi, è conservabile fino a due anni ed è efficace contro muffa grigia e Sclerotinia su varie colture ma non è miscelabile con altri fungicidi. Lieviti come agenti di biocontrollo e principali prodotti autorizzati Yeasts are unicellular shaped fungi that reproduce either by budding or by binary fission. They are present in all environments, are easy to grow and industrial level and to formulate and have a high resistance to stress . No safety risks are associated with yeasts or in any case they are very limited in fact many species are used in the food sector. Candida oleophila It was the first yeast to be developed as a commercial plant protection product . In particular, two are the most studied strains, l-182 and OR . Nexy is the commercial product composed of 57% of the O strain and acts in post harvest against Botrytis cinerea of apple and pear , and against Penicillium expansum on citrus . Aureobasidium pullulans Also known as black yeast , it has a high degree of polymorphism, it is also ubiquitous and saprophytic. It acts as a bactericide against Erwinia amylovora and as a fungicide against Penicillium expansum on pome fruit and against Botrytis cinerea on grapevine. It adapts to stressful environmental conditions such as hypersalinity, acidity, cold and lack of nutrients. In conditions of stress of the plant wild strains of A. pullulans are naturally present on plants, the treatment allows to increase the quantity. As for the induction of resistance, the yeast produces cutinase which in the plant determines the increase of the cell division of the epidermis with the subsequent production of phytoalexins and lowering of the pH in the colonized environments (bacteriostatic effect) . Botector new and Blossom protect new are two commercial products, both of which consist of two different yeast strains. The first is active against Botrytis cinerea on tomato, aubergine and strawberry , the second is effective against Erwinia amylovora on pear, apple, quince, medlar, Japanese medlar, nashi and wild apple . Saccharomyces cerevisiae It is considered a model organism because it is very easy to produce. Romeo is the commercial product composed of cell wall fractions of the LAS117 strain active on grapevine against powdery mildew, downy mildew and botrytis . However, it is always recommended to apply it in a mixture with an antiperonosporic because its activity is only partial. Filamentous mushrooms as biocontrol agents and main authorized products Although in this case the studies have been many and dedicated to various species and strains, mainly strains of species of the genus Trichoderma are authorized , especially for root diseases. Trichoderma It has all the mechanisms of action; As for mycoprassitism, Trichoderma secretes enzymes that degrade the cell wall of the host fungus. The direct action, on the other hand, involves the production of antibiotic substances: volatile substances, water-soluble compounds and peptaiboles. Competition allows Trichoderma to control Botrytis cinereaon the grape colonizing by excluding the pathogen from its site of infection. Finally, it has an excellent interaction with the plant, colonizes the roots well and can also produce phytohormones that promote their growth. Ampelomyces quisqualis Ascomycete and mycoparasite of several species of Erysiphales , it is the most studied biocontrol agent. The first formulation of the CNCM-1572 strain has been marketed as AQ10 since the 1990s. It is very polyphagous therefore it can be used on many species and oidae: it attacks more than 65 different species of powdery mildew on at least 256 species of plants. But be careful because it only checks powdery mildew infections in progress (early applications) because to survive it must colonize the host. It acts by attacking the mycelium, hyphae and conidiophore branches, after forming the appressorium it penetrates the host mechanically or enzymatically. Following the degeneration of the cell cytoplasm, the destruction of the colonies takes place in 5-7 days and the wintering forms (chasmothecia) are also parasitized. The commercial AQ10 strain is active against powdery mildew on cucurbits, nightshades, strawberries, roses, table and wine grapes. It should be used in strategy with other products for at least two consecutive applications spaced from 7 to 10 days. It suffers from high temperatures and dehydration before the penetration of the pathogen, therefore, it should be applied in the early morning or evening. It is also active even at low temperatures, it does not cause phytotoxicity problems, it is selective towards auxiliaries, it does not develop resistant powdery mildew strains, it does not interfere in the wine fermentation processes, it is not toxic for the environment and man and helps to reduce the residue of synthetic compounds at harvest. Conclusions In Europe, among the products authorized or in the authorization phase, there is a large presence of Trichoderma . In the future there will be more and more tendency to use new strains of the same species because if you start from a new species you have to start from scratch and check all the effects, in the cases of microorganisms that have been used for many years it is certainly easier. Trichoderma- based products are almost all authorized for soil diseases but they are broad-spectrum products and still have many potentials that have not yet been exploited. (Click on the image to enlarge) What are the advantages of using oomycetes, fungi and yeasts for biocontrol? They leave no residue; they do not interfere with fermentation; possono essere applicati in prossimità alla raccolta; aiutano a ridurre la presenza di residui; possono essere inseriti nelle strategie anti resistenza; sono un valido strumento nell'agricoltura biologica e integrata; non sono tossici per l'ambiente, l'uomo e gli animali; non danno problemi di fitotossicità. Among the disadvantages it must be said that these microorganisms are very delicate, in fact one of the main factors that can reduce the effectiveness of the product is the incorrect storage which often occurs at too high temperatures or in the presence of humidity during transport or storage in retail outlets. . The use of microorganisms for biocontrol is also limited : they are not miscible with other fungicides, they cannot be kept in suspension for a long time, the atomizer barrel must be rinsed carefully before use, the product has an expiry date. I nomi dei formulati commerciali riportati in questo articolo, così come le relative informazioni, sono quelli emersi nel corso delle lezioni del master, senza pretesa di esaustività. Per la panoramica completa dei fitofarmaci registrati dal Ministero della Salute si rimanda al sito delle aziende e alla banca dati Fitogest appartenente al network di Image Line (a cui appartiene anche AgroNotizie). Biosolution Academy è il corso per la formazione di esperti di alto livello nello sviluppo di alternative ai prodotti chimici di sintesi per la difesa delle piante dagli organismi dannosi (biosolution). È organizzato dall'Università Cattolica del Sacro Cuore e si rivolge a dipendenti di aziende che producono e commercializzano biosolution, agronomi, consulenti e studenti. Obiettivo di Biosolution Academy è quello di formare una nuova figura professionale, che guarda alle biosolution con una conoscenza profonda e trasversale. L'Academy sarà organizzata tramite una didattica innovativa ed esperienziale, con la collaborazione delle aziende del settore, delle migliori competenze dalla ricerca universitaria e dal mondo professionale. Per informazioni ed iscrizioni visita la pagina del corso. AgroNotizie è media partner del corso. GOWAN ITALIA S.r.l. Via Morgagni, 68 - 48018 Faenza (RA) © Copyright 2014 e succ. 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