Changes in "natural antibiotic" metabolite composition during tetraploid wheat domestication

Yuval Ben-Abu,Mark Itsko

doi:10.1038/s41598-021-98764-5

Abstract

Gramineous plants protect their seeds from a variety of biotic stresses by producing toxic and deterrent secondary metabolites such as benzoxazinoids. It is unclear how the composition and abundance of these natural toxins has changed over the course of crop-plant domestication. To address this uncertainty, we characterized differences in metabolic levels of benzoxazinoids and their derivatives, between 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. Three-dimensional principal component analysis of mass spectrometry data of wheat metabolites showed with high resolution clear differences between metabolic profiles of WEW, DEW, and durum (LD + MD) and similarity in the metabolic profiles of the two durum lines (LD and MD) that is coherent with the phylogenetic relationship between the corresponding wheat lines. Moreover, our results indicated that some secondary metabolites involved in plant defense mechanisms became significantly more abundant during wheat domestication, while other defensive metabolites decreased or were lost. These metabolic changes reflect the beneficial or detrimental roles the corresponding metabolites might play during the domestication of three taxonomic subspecies of tetraploid wheat (Triticum turgidum).

Highlights

Gramineous plants such as wheat (Triticum aestivum), rye (Secale cereale) and maize (Zea mays) produce an indole-derived class of toxic and deterrent secondary metabolites called benzoxazinoids to defend themselves against microbial pathogens, weeds, insects, or h erbivores[1,2,3,4,5,6,7,8,9,10,11]
While domesticated emmer wheat (DEW) had been a prominent type of cultivated wheat for several millennia, today it exists only as a relatively minor crop, having been replaced, mostly during the Roman period, by durum wheat (Triticum turgidum ssp. durum, genome BBAA, 4x, 2n = 28), which is non-fragile and freethreshing[16,18,23]
Domesticated durum varieties can be classified into ancient landraces of durum (LD), which were selected by farmers, were locally adapted and grew under low input farming[19], and modern durum (MD) varieties, dwarf and semidwarf lines, which were developed by plant breeders and grown on modern farms (Fig. 1)

Summary

Introduction

Gramineous plants such as wheat (Triticum aestivum), rye (Secale cereale) and maize (Zea mays) produce an indole-derived class of toxic and deterrent secondary metabolites called benzoxazinoids to defend themselves against microbial pathogens, weeds, insects, or h erbivores[1,2,3,4,5,6,7,8,9,10,11]. The cornerstone of the agricultural revolution, took place about 11,000 years ago with the appearance of the first known form of domesticated emmer wheat While DEW had been a prominent type of cultivated wheat for several millennia, today it exists only as a relatively minor crop, having been replaced, mostly during the Roman period, by durum wheat Hexaploid bread wheat (Triticum aestivum ssp aestivum genome BBAADD, 6x, 2n = 42) was formed ~ 9000 years ago through hybridization between a tetraploid (genome BBAA) and a diploid wheat, Aegilops tauschii To address the question as to how the profile of benzoxazinoids changed in the wheat during its domestication we compared levels of these metabolites in wild emmer (WEW), domesticated emmer (DEW) and durum in two types of plant tissue seed kernel and endosperm

Methods

Results

Conclusion