Changes in "Natural Antibiotic" Metabolite Composition During Tetraploid Wheat Domestication

Abstract Plants defend themselves by producing toxins and deterrent metabolites. However, it is unclear how the composition and abundance of these natural pesticides have changed over the course of crop-plant domestication. To address this uncertainty, we characterized differences in secondary metabolites, particularly Benzoxazinoids and its derivates, among four lines of tetraploid wheat: wild emmer wheat (WEW), the direct progenitor of modern wheat; non-fragile domesticated emmer wheat (DEW), which was first domesticated about 11,000 years ago; the subsequently developed non-fragile and free-threshing durum landraces (LD); and modern durum (MD) varieties. Mass spectrometry analyses showed that the metabolome of the embryo of the mature kernel was more complex than that of the endosperm. Clear differences were observed among the metabolic profiles of WEW, DEW, and durum (LD + MD); the metabolic profiles of the two durum lines (LD and MD) were similar. Our results indicated that underappreciated classes of metabolites involved in plant defense mechanisms became significantly more abundant during wheat domestication, while other defensive metabolites decreased or were lost. It may be that the use of industrial pesticides has led to the loss of these endogenous defense metabolites. The re-expression of such “lost” metabolites in modern wheat might help to improve crop resistance, while reducing dependence on harmful industrial pesticides. In addition, we detected alterations in antioxidant composition among wheat lines, as well as increases in levels of plant hormones and antibiotic substances in the more modern lines as compared to the more primitive lines. Here, we show how DIMBOA and its derivates change during wheat domestication, and how this change may effect on the domestication of three taxonomic subspecies of tetraploid wheat (Triticum turgidum).