Effect of ethylene and 1-MCP treatments on strawberry fruit ripening

Abstract

Strawberry is a soft fruit, considered as non-climacteric, being auxins the main hormones that regulate the ripening process. Nowadays, the role of ethylene in strawberry ripening is not clear and several works have considered a revision of the possible role of this hormone. Strawberry fruit were harvested at white stage and treated with ethephon, an ethylene releasing reagent, or 1-methylcyclopropene (1-MCP), a competitive inhibitor of ethylene action. The effects of the treatments on fruit quality parameters and on the activity of enzymes related to anthocyanin synthesis and cell wall degradation were evaluated. Some aspects of ripening were accelerated (anthocyanin accumulation, total sugar content and increment of phenylalanine-ammonia-lyase (PAL; EC 4.3.1.24) and â-galactosidase (â-Gal; EC 3.2.1.23) activities), while others were repressed (chlorophyll levels and increment of endo-1,4-â-glucanase (EGase; EC 3.2.1.4) and â-xylosidase (â-Xyl; EC 3.2.1.37) activities) or unchanged (reducing sugar content, pH, titratable acidity and á-L-arabinofuranosidase (á-Ara; EC 3.2.1.55) activity) by ethylene. 1-MCP treatment caused the opposite effect. However, its effects were more pronounced, particularly in anthocyanin accumulation, phenolics, PAL and polygalacturonase (PG; EC 3.2.1.15 and EC 3.2.1.67) activities. These observations probably indicate that strawberry produce low levels of ethylene that are enough to regulate some ripening aspects.