Metabolomics, metabolic diversity and genetic variation in crops

The metabolome represents a critical aspect of a plant's physiology, growth characteristics and, ultimately, economic value. Metabolic changes underpin plant development and responses to applied stresses, whilst quality traits in many important crops and ornamental plants are dependent on metabolic composition. It is also frequently reasoned that metabolic information reflects biological endpoints more accurately than transcript or protein analysis. As such, the science of metabolomics has proven to be of increasing popularity in assessing genotypic and phenotypic diversity in plants, in defining biochemical changes associated with developmental changes during plant growth and, increasingly, in compositional comparisons. The postulated value of this metabolic information resides primarily in its potential to support breeding and selection of novel yield-enhanced and nutritionally improved crops. Plants display remarkable genetic plasticity which has served to facilitate the development of an extraordinary range of genetically distinct and metabolically diverse cultivars for any given plant species. Despite concerns regarding potential loss of genetic diversity through domestication, genetic resources still exist through wild and exotic germplasms. Additionally, emerging biotechnological approaches such as RNAi silencing and the transgenic modification of regulatory genes offer new and fascinating opportunities for enhancing diversity and eliciting trait improvements. This review is intended to promote the view that metabolomics, through comparative assessments of metabolic diversity in domesticated and non-domesticated plants, and through evaluations of the compositional impact of metabolic engineering efforts can support breeding programmes designed to elicit trait improvements.