ENHANCING PHYSIOLOGICAL PARAMETERS IMPROVES RESISTANCE AGAINST ALTERNARIA ALTERNATE IN 'FORTUNE' MANDARIN

The appearance of Alternaria brown spot (ABS) in Spanish citrus-growing regions forced the abandonment of ‘Fortune’ mandarin production given the difficulty of controlling this disease using fungicides. Environmental concerns have prompted governments to promote alternatives to applying synthetic chemicals in order to reduce the risks and impacts of pesticide use. The development of novel resistance-inducing chemicals is an alternative to protect crops against pathogens. In recent years, strategies based on using natural compounds have shown that soil-drench treatments with hexanoic acid (Hx) protect mandarins against Alternaria alternate. The present work analysed both the effectiveness of Hx in controlling the ABS disease in ‘Fortune’ trees, and the physiological and metabolic changes associated with Hx treatment. The preliminary results indicate that all the analysed physiological parameters improve, including transpiration, photosynthesis or chlorophyll levels. Moreover, the metabolomics study of A. alternate infection and Hx treatment has found significant changes in the metabolic profile of the plant associated with both infection and treatment. In conclusion, these studies shed light on the complexity underlying induced disease resistance (IR). Hx-IR is an attractive tool for the molecular characterisation of the priming phenomenon and integrated pest management strategies, and it offers the advantage of using a natural compound.