Synthesis and accumulation of amylase-trypsin inhibitors and changes in carbohydrate profile during grain development of bread wheat (Triticum aestivum L.)

Lisa Call,Heinrich Grausgruber,Elisabeth Haider,Elisabeth Reiter,Stefano D’Amico

doi:10.1186/s12870-021-02886-x

Abstract

BackgroundRecent studies indicate that amylase-trypsin inhibitors (ATIs) and certain carbohydrates referred to as FODMAPs (fermentable oligo-, di-, monosaccharides and polyols) play an important role in promoting wheat sensitivity. Hitherto, no study has investigated the accumulation of ATIs during the development of the wheat caryopsis. We collected caryopses of common wheat cv. ‘Arnold’ at eight different grain developmental stages to study compositional changes in ATI and FODMAP content.ResultsThe harvested caryopses were analysed for their size, protein and carbohydrate concentrations. ATIs were further characterized by MALDI-TOF MS, and their trypsin inhibition was evaluated by an enzymatic assay. The results showed that ATI accumulation started about 1 week after anthesis and subsequently increased steadily until physiological maturity. However, the biological activity of ATIs in terms of enzyme inhibition was not detectable before about 4 weeks after anthesis. Carbohydrate analysis revealed the abundance of short-chain fructans in early stages of grain development, whereas non-water-soluble carbohydrates increased during later developmental stages.ConclusionsThe results provide new insights into the complex metabolisms during grain filling and maturation, with particular emphasis on the ATI content as well as the inhibitory potential towards trypsin. The time lag between ATI accumulation and development of their biological activity is possibly attributed to the assembling of ATIs to dimers and tetramers, which seems to be crucial for their inhibitory potential.

Highlights

IntroductionRecent studies indicate that amylase-trypsin inhibitors (ATIs) and certain carbohydrates referred to as Fermentable oligo- (FODMAPs) (fermentable oligo-, di-, monosaccharides and polyols) play an important role in promoting wheat sensitivity
Recent studies indicate that amylase-trypsin inhibitors (ATIs) and certain carbohydrates referred to as Fermentable oligo- (FODMAPs) play an important role in promoting wheat sensitivity
ATI concentration and activity were found to increase throughout grain development, while fructans were abundant in immature wheat kernels

Summary

Introduction

Recent studies indicate that amylase-trypsin inhibitors (ATIs) and certain carbohydrates referred to as FODMAPs (fermentable oligo-, di-, monosaccharides and polyols) play an important role in promoting wheat sensitivity. ATIs have the potential to inhibit the activity of two important digestive enzymes in the gastrointestinal system, amylase and trypsin, causing a significant impairment of digestion [7]. Due to this inhibitory feature, ATIs and other metabolic proteins are considered crucial for the natural defence mechanism of the plant itself. They are located in the endosperm of cereal seeds, where they defend starch and protein reserves by blocking amylase and trypsin activities of pathogenic fungi or invading pests [1, 8, 9]. The inhibitory activity of ATIs is strongly dependent on the 3D-structure and the state of aggregation [1]

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Discussion

Conclusion