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ABSTRACT
Alternaría alternata (Fr.) Keissl. 1912 is one of the main fungal pathogens that infect tomato (Solanum lycopersícum L.) during cold storage affecting postharvest quality and marketing. During fungal infections, fruits and fungi release specific volatile metabolites (VM) that could alter the fruit aroma, or could mediate resistance response in the fruit, or they also could suggest the possible status of fungal attack. The detection of the VM released during the tomato-Alternaría interaction could contribute to the development of ecofriendly and harmless strategies for its control. In this study, the profile of VM of fresh tomatoes inoculated with A. alternata, were analyzed by solid phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS) during storage at 15 and 20 °C for 48 h, respectively. Changes in the profile of VM were observed between control and inoculated fruit since the first few hour post-inoculation. Some VM (3-methyl-2-butenal, dimethyl disulfide, 1-butenol, hexanol, 2-methyl-1-butanol acetate, among others) were only detected in inoculated fruit, so they appear to be synthesized by the presence of the pathogen. Also, a marked increase of 3-methyl-1-butanol and 6-methyl-5-hepten-1-one were observed in inoculated fruit, and they were progressive over time particularly at 20 °C. In conclusion, A. alternata induced changes in the profile of volatile metabolites released by tomato fruit. Some of the VM released during tomato-A. alternata interaction, were synthesized or stimulated by the fungal attack. These results contribute to the current knowledge about the profile of VM released during the fruit-pathogen interaction.
Key words: Volatile metabolites, fresh tomatoes, Alternaría alternata, cold storage temperatures, SPMEGC-MS.
INTRODUCTION
Tomato (Solanum lycopersícum L.) is a commercially important vegetable crop worldwide, with a production about 200 million tons on 4.8 million hectares (FAOSTAT, 2015). Consumers highly accept it because of the quality, sensory characteristics and important source of nutrients. However, due to its physiology and high water content, it is highly perishable and susceptible to fungal attack, affecting the quality and leading to significant postharvest losses. After harvest and under cold storage conditions, tomato is susceptible to infection caused by necrotrophic fungus Alternaría alternata (Fr.) Keissl. 1912 (Zitter and Wien, 1984; Ruelas et al., 2006), which is one of the most common pathogen causing spoiled tomatoes and it is responsible for black mold disease (Troncoso-Rojas and Tiznado-Hernández, 2014)....