Methyl jasmonate mediated modulation of lipoxygenase pathway modifies aroma biosynthesis during ripening of 'Regina' sweet cherry (Prunus avium L.)

Abstract

Fruit aroma is a crucial characteristic of consumers’ perception of quality. The aroma is the result of several volatile compounds that are metabolized during fruit development. Changes in the profile of volatile compounds can result in the development of off-flavors. In 'Regina' sweet cherry (Prunus avium L.), an herbaceous off-flavor may develop, causing an unpleasant taste experience for consumers, resulting in a negative perception in the market. Previous research has suggested a link between the herbaceous off-flavor and volatile compounds derived from the lipoxygenase (LOX) pathway. Among the many metabolites downstream of the LOX pathway, methyl jasmonate (MeJA) is a crucial phytohormone that regulates volatile production. To better understand the biological basis of the herbaceous off-flavor, we studied the effect of a foliar application of MeJa (0.4 mM) at the veraison stage on off-flavor occurrence, quality parameters, LOX-derived volatile compounds, and LOX gene expression levels. The primary sources of variation in off-flavor incidence were the season effect and phenological stage. The MeJA application influenced the aroma profile of sweet cherries by increasing the concentration of C6 volatile aldehydes, which contribute to the herbaceous/ grassy off-flavor while reducing the alcohols and esters. The expressions of PaLOX2, PaLOX4, PaLOX5, PaLOX10, PaLOX7, and PaLOX11 were found to be differentially regulated in sweet cherries treated with MeJA. Thus, our results suggest that MeJA influences the aroma profile of 'Regina' sweet cherry and also contribute to the production of unripe flavors.