Effect of preharvest application of hexanal and growth regulators in enhancing shelf life and regulation of membrane-associated genes in strawberry

Abstract

The role of hormones during fruit development and ripening in strawberry (Fragaria × ananassis poorly understood. In this study, two strawberry cultivars (‘Jewel’ and ‘Wendy’) were chosen based on their shelf life quality, which were intermediate and excellent, respectively. Hexanal and growth regulators were applied to the fruit as two preharvest sprays. Fruits treated with “Enhanced Freshness Formulation” (a formulation with hexanal as a key ingredienshowed improvement in the shelf life of both cultivars. Auxin application reduced loss of fruit firmness and abscisic acid was able to accelerate the ripening process without having a significant effect on the relevant fruit quality parameters. The regulation of gene expression during ripening in relation to hexanal and hormones was examined in 21 genes potentially involved in cell wall degradation. Gene expression profiles showed similar patterns in the two cultivars, with more prominent amplitude in ‘Wendy’. The expression of hormone-responsive genes responded in an antagonistic manner to exogenous hormone applications, supporting their role in ripening and fruit development. Hexanal application induced a clear reduction in the transcript level of two phospholipase D genes and other key enzymes involved in cell wall degradation. These findings indicate that ripening in strawberry is associated with the expression of specific genes and the modulation of this gene expression by hexanal supports its role in increasing fruit shelf life.