Preventive and post‐infection control of Botrytis cinerea in tomato plants by hexanoic acid

Abstract

The antifungal activity of hexanoic acid on the phytopathogen Botrytis cinerea was studied. This chemical inhibited both spore germination and mycelial growth in vitro in a concentration-and pH-dependent manner, and stopped spore germination at a very early stage, preventing germ-tube development. The minimum fungicidal concentration (MFC) for in vitro spore germination was 16 m m . Hexanoic acid also inhibited in vitro mycelial growth of germinated spores at an MFC of 12 m m . Studies performed to characterize the mechanisms underlying the antimicrobial effect of hexanoic acid showed that it alters fungal membrane permeability. In addition, hexanoic acid treatment increased the levels of spermine, spermidine, putrescine and cadaverine in B. cinerea mycelia. Spray application of hexanoic acid at fungicidal concentrations on 4-week-old tomato plants prior to fungal inoculation reduced necrosis diameter by approximately 60%. Application of the same hexanoic acid concentrations on previously infected plants reduced further necrosis expansion by around 30%. The results suggest that this chemical acts as a preventive and curative fungicide. Interestingly, treatments with hexanoic acid at concentrations below the MFC in hydroponic solution prior to fungal inoculation significantly reduced necrosis area. These results suggest an inducer effect of plant responses for hexanoic acid treatments at these concentrations. Hexanoic acid is a good candidate for safe antifungal treatments for the control of B. cinerea , which is responsible for many economic losses on fruits, vegetables and flowers.

Induced resistance in citrus by hexanoic acid

“…tomato and pepper Achuo et al, 2004;Leyva et al, 2008;, apple (Ortega et al, 1998;Brisset et al, 2000;Macarisin et al, 2009;Yi et al, 2012), pear (Faize et al, 2004;Yu et al, 2014), and several reviews about induced resistance in crops have been published (Vallad and Goodman, 2004;Walters et al, 2008;Walters and Fountaine, 2009;Ahmad et al, 2010;Gozzo and Faoro, 2013). In the last few years, some studies about the efficacy of priming agents have been tested in citrus crops.…”

“…Thus, the plant immune system is controlled by a network of signalling pathways, and the cross-talk between these pathways results in variable responses depending on the challenging pathogens (Glazebrook, 2005;Pieterse et al, 2009). Some of these defensive mechanisms can be induced by certain natural (Leyva et al, 2008; or synthetic (Beckers and Conrath, 2007) compounds.…”

Estudio integral de los mecanismos de resistencia inducida. Inductores frente a estrés biótico y abiótico

“…The molecular basis of priming has recently started to be unraveled, but is still poorly understood. In recent years, our research group has focused on studying inducers of resistance, such as natural 6C monocarboxylic hexanoic acid (Hx), which displays effectiveness in tomato plants against necrotrophic fungi B. cinerea (Leyva et al, 2008;Vicedo et al, 2009). Treating the roots of 4-week-old plants with Hx at concentrations below 1 mM for 48 h prior to infection has been reported to significantly reduce disease incidence (Vicedo et al, 2009).…”

“…2b) We tested the efficacy of Hx treatment as an inducer of resistance in melon plants against MNSV. Based on previous data of Hx-IR in tomato plants against B. cinerea and P. syringae (Leyva et al, 2008;Vicedo et al, 2009;Scalschi et al, 2013), we set up Hx treatments in melon plants, which were applied by either foliar spray or soil drench. We checked different concentrations and patterns of treatment applications (Fig.…”

“…Hormone extraction and quantification were performed as described in Flors et al (2008). Briefly, fresh material was frozen in liquid nitrogen.…”