STRAWBERRY VOLATILE COMPOUNDS COULD INFLUENCE BOTRYTIS CINEREA AND COLLETOTRICHUM ACUTATUM DEVELOPMENT

Recent studies have shown that plant volatile organic compounds may have important roles as infochemicals for recognition of typical host and assessment of host status for fungal pathogens. To examine the influence of strawberry volatiles on Botrytis cinerea and Colletotrichum acutatum development, thirty-four strawberry volatiles were tested against the pathogens’ conidial germination and mycelial growth; changes in susceptibility to B. cinerea and C. acutatum infections and in volatile constituents were then examined in ‘Alba’ and ‘Monterey’ strawberries harvested at four ripening stages. Some compounds influenced the development of pathogens either by stimulant and/or inhibitory effects, in relation to their concentration. In particular, ethyl butyrate and furaneol promoted B. cinerea conidial germination in a wide range of concentrations (from 0.062 to 12.30 µL/L) and C. acutatum mycelial growth at 0.062 µL/L; in addition, β-ionone (0.062 µL/L) stimulated B. cinerea conidial germination and the mycelial growth of both pathogens. trans-2-Hexenal completely inhibited B. cinerea and C. acutatum conidial germination at 12.3 µL/L , while the same concentration of nonanal showed the best inhibition of B. cinerea mycelial growth (-66.8%). An increase of most volatiles having stimulant activity on pathogens (methyl butyrate, ethyl butyrate, 2-methylbutyl acetate, hexyl acetate and hexyl butyrate) and a decrease of compounds that inhibited them (trans-2-hexenal and nonanal) were observed as ripening progressed in two cultivars of strawberry with different aroma profiles. Results of our study suggest that fruit volatiles may influence the complex process of inhibition and/or stimulation of B. cinerea and C. acutatum latent infections