Plasticity of the cucumber peel metabolome
Our previous analyses of the cucumber peel metabolome revealed many developmental changes. Notably, the majority of ions detected showed age-related changes in abundance, either increasing or decreasing with age. These analyses included only two cucumber genotypes, both of the processing (pickling) market class. To examine if other cucumber cultivars exhibit such strong developmental changes in their metabolomes, we performed untargeted metabolomic analyses on four slicing cucumber cultivars. We observed similar metabolome-wide developmental changes in both cucumber market classes. We further observed that metabolomes of young fruit from all cultivars were similar to each other. However, the metabolite profiles appeared to diverge as the fruit approached full size, resulting in differentiation by market class. There have been previous metabolomic studies comparing different stages of fruit development, most with an emphasis on phases of ripening. However, in this study, we analyzed peels from early stages of cucumber fruit development, as these are more pertinent to cucumber production. These initial results reveal that, though early fruit development is a relatively understudied period, it represents a dynamic period in the cucumber peel metabolome which, in turn, may have a direct impact on flavor, aroma and defense.