Effect of 1-methylcyclopropene on the development of black mold disease and its potential effect on alternariol and alternariol monomethyl ether biosynthesis on tomatoes infected with Alternaria alternata

Ethylene is a naturally produced plant regulator involved in several plant functions, such as regulation of fruit ripening. Inhibition of ethylene perception by using 1-methylcyclopropene (1-MCP) slows down the ripening of the fruit maintaining its quality and freshness. The use of 1-MCP is a commercial strategy commonly used in the food industry to extend the postharvest life of several fruits, including tomatoes. To assess how 1-MCP affected infection by Alternaria alternata on tomatoes, three different cultivars were artificially inoculated with 5 μL of an A. alternata conidial suspension (105 conidia/mL). Tomatoeswere treatedwith 0.6 μL/L of 1-MCP for 24 h. Spiked but untreated tomatoes were considered controls. Then, fruit were stored 6 days at 10 °C and one more week at 20 °C to simulate shelf-life. Fungal growth development and mycotoxin production (alternariol, AOH and alternariol monomethyl ether, AME) were assessed both on the first and on the second week. After the first 6 days at 10 °C, in just one variety the black mold disease was higher in the 1-MCP treated samples. However, after two weeks of storage, in all cases, tomatoes treated with 1-MCP showed more significant fungal growth disease. Regarding mycotoxin production, no large differences were observed among different treatments, which was corroborated with gene expression analysis of pksJ, a gene related to AOH and AME biosynthesis.We thank the Postharvest Programme of IRTA, especially to J. Usall, E. Costa and R. Altisent, for kindly offering us their postharvest chambers and laboratories and for helping us with the fruit quality measurements. We are also grateful to the Catalonian Government (FI-DGR 2013) (XaRTA-Reference Network on Food Technology) for their financial support. N. Estiarte thanks the Secretaria de Universitats i Recerca del Departament d'Economia i Coneixement of the Generalitat de Catalunya for the pre-doctoral grant