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El amarillamiento de la hoja, causado por el virus del amarillamiento de la caña de azúcar (SCYLV), está distribuido mundialmente en las regiones cañeras; sin embargo, se desconoce su incidencia y distribución en la Argentina. Por ello se plantearon dos grandes objetivos: i) analizar la distribución en el área cañera de Tucumán de SCYLV, caracterizar el virus y determinar la correlación entre la presencia del este y los síntomas de la enfermedad, y ii) evaluar el comportamiento de progenitores del Subprograma de Mejoramiento Genético de la Caña de Azúcar (SMGCA) de la Estación Experimental Agroindustrial Obispo Colombres (EEAOC) frente al virus, comparando metodologías de diagnóstico. Para cumplir el primer objetivo, se colectaron 146 muestras de hojas de caña de azúcar con y sin síntomas de amarillamiento, de variedades comerciales, clones avanzados en las etapas finales de selección y progenitores del SMGCA de la EEAOC, en la provincia de Tucumán, en 2011 y 2012. El SCYLV se detectó en 26 muestras mediante RT-PCR, todas correspondieron al genotipo BRA-PER del virus. El análisis filogenético del gen de la proteína de la cápside permitió la agrupación de razas y la distinción entre aislados. La correlación entre la presencia del virus y los síntomas de la enfermedad fue positiva, baja, pero estadísticamente significativa. Respecto al segundo objetivo, en 2013, 2015, 2016 y 2017 se tomaron muestras de los progenitores utilizados en el SMGCA y se diagnosticó la presencia de SCYLV mediante técnicas moleculares, empleando dos pares de cebadores, y serológicas. El 75% de los genotipos evaluados resultó libre del virus durante el período de evaluación considerado. Se detectó que la RT-PCR empleando los cebadores SCYLVf1/r1 sería más sensible que con el par YLS111/462 y que el diagnóstico molecular fue más sensible que el diagnóstico serológico.

The production of bioethanol and sugar from sugarcane is an important economic activity in several countries. Sugarcane is susceptible to different phytopathogens. Over the last years, the red stripe disease caused by the bacterium Acidovorax avenae subsp. avenae produced significant losses in sugarcane crops. Bio-nanotechnology emerged as an eco-friendly alternative to the biosynthesis of antimicrobial molecules. The aims of this study were to (a) produce extracellular silver nanoparticles using the heavy metal resistant strain Amycolatopsis tucumanensis, (b) evaluate their antibacterial in vitro effect and (c) determine the potential of silver nanoparticles to protect sugarcane against red stripe disease.Amycolatopsis tucumanensis synthesized spherical silver nanoparticles with an average size of 35 nm. Nanoparticles were able to control the growth of A. avenae subsp. avenae in in vitro assays. In addition, in vivo assays in sugarcane showed a control upon the red stripe disease when silver nanoparticles were applied as preventive treatment. The Disease Severity Index was 28.94% when silver nanoparticles were applied 3 days before inoculation with A. avenae subsp. avenae. To our knowledge, this is the first report of silver nanoparticles extracellularly synthesized by an Amycolatopsis strain that were able to inhibited the growth of A. avenae subsp. avenae and control the red stripe disease in sugarcane.

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 by the strawberry fungal pathogen Acremonium strictum. Fungal fermentation conditions and downstream processing were determined to maximize extracellular protein production, product stability and a high plant defense-eliciting activity, as monitored by anthracnose resistance in supernatant-treated strawberry plants subsequently infected with a virulent strain of Colletotrichum acutatum. Fermentation batches were shown to reduce anthracnose development by 30–60% as compared to infected non-treated plants. Product formulation was shown to be stable for 6 months when stored at temperatures up to 45°C and toxicological tests showed that PSP1 was harmless to beneficial organisms and non-toxic to mammalian species at concentrations 50 times higher than those used in plant experiments. Furthermore, disease protection studies using dilutions of PSP1 indicated that there is a minimum threshold protease activity needed to induce pathogen defense in strawberry and that this induction effect is dose-independent. A significant characteristic of PSP1 is its broad-range protection against different diseases in various crop species. In soybean, PSP1 reduced the symptomatology by 70% of Corynespora cassiicola, etiological agent of the target spot. This protection effect was similar to the commercial inducer BION 500 WG based on BTH, and both products were shown to induce an oxidative burst and up-regulated PR1-gene expression in soybean. Furthermore, a double PSP1-treatment on greenhouse-grown sugarcane plants provided protection against bacterial red stripe disease caused by Acidovorax avenae and a double foliar application of PSP1 on field-grown wheat 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 control against both bacterial and fungal pathogens in both monocot and dicot crop species, which together with its low production cost, effectiveness at low concentrations, long shelf-life, tolerance to high temperatures, harmlessness to non-target organisms and simple handling and application, make PSP1 a very promising candidate for effective and sustainable disease management in many crop species.