Development of PSP1, a Biostimulant Based on the Elicitor AsES for Disease Management in Monocot and Dicot Crops

BUDEGUER, FLORENCIA; DI PETO, PÍA; MORETTI, ENRIQUE R.; CASTAGNARO, ATILIO P.; DURMAN, SANDRA B.; BERTANI, ROMINA P.; FILIPPONE, MARÍA P.; WELIN, BJÖRN; CHALFOUN, NADIA R.; CARO, MARÍA D. P.; STENGLEIN, SEBASTIÁN A.; DÍAZ RICCI, JUAN C.

Frontiers in Plant Science

Frontiers Media S.A.

Lugar: Lausanne; Año: 2018 vol. 9

In this work, we present a novel biostimulant for sustainable crop disease management,PSP1, based on the plant defense-elicitor AsES, an extracellular protease produced bythe strawberry fungal pathogen Acremonium strictum. Fungal fermentation conditionsand downstream processing were determined to maximize extracellular proteinproduction, product stability and a high plant defense-eliciting activity, as monitored byanthracnose resistance in supernatant-treated strawberry plants subsequently infectedwith a virulent strain of Colletotrichum acutatum. Fermentation batches were shownto reduce anthracnose development by 30?60% as compared to infected non-treatedplants. Product formulation was shown to be stable for 6 months when stored attemperatures up to 45C and toxicological tests showed that PSP1 was harmless tobeneficial organisms and non-toxic to mammalian species at concentrations 50 timeshigher than those used in plant experiments. Furthermore, disease protection studiesusing dilutions of PSP1 indicated that there is a minimum threshold protease activityneeded to induce pathogen defense in strawberry and that this induction effect isdose-independent. A significant characteristic of PSP1 is its broad-range protectionagainst different diseases in various crop species. In soybean, PSP1 reduced thesymptomatology by 70% of Corynespora cassiicola, etiological agent of the targetspot. This protection effect was similar to the commercial inducer BION 500 WGbased on BTH, and both products were shown to induce an oxidative burst and upregulatedPR1-gene expression in soybean. Furthermore, a double PSP1-treatment ongreenhouse-grown sugarcane plants provided protection against bacterial red stripedisease caused by Acidovorax avenae and a double foliar application of PSP1 on fieldgrownwheat plants significantly increased resistance against Fusarium graminearum,causal agent of head blight disease, manifested mainly in an increased seed germination rate. In summary, these disease protection studies demonstrated an effective controlagainst both bacterial and fungal pathogens in both monocot and dicot crop species,which together with its low production cost, effectiveness at low concentrations, longshelf-life, tolerance to high temperatures, harmlessness to non-target organisms andsimple handling and application, make PSP1 a very promising candidate for effectiveand sustainable disease management in many crop species.