Genetic architecture underlying the expression of eight α-amylase trypsin inhibitors

Abstract

Key message Wheat cultivars largely differ in the content and composition of ATI proteins, but heritability was quite low for six out of eight ATIs. The genetic architecture of ATI proteins is built up of few major and numerous small effect QTL. Abstract Amylase trypsin inhibitors (ATIs) are important allergens in baker’s asthma and suspected triggers of non-celiac wheat sensitivity (NCWS) inducing intestinal and extra-intestinal inflammation. As studies on the expression and genetic architecture of ATI proteins in wheat are lacking, we evaluated 149 European old and modern bread wheat cultivars grown at three different field locations for their content of eight ATI proteins. Large differences in the content and composition of ATIs in the different cultivars were identified ranging from 3.76 pmol for ATI CM2 to 80.4 pmol for ATI 0.19, with up to 2.5-fold variation in CM-type and up to sixfold variation in mono/dimeric ATIs. Generally, heritability estimates were low except for ATI 0.28 and ATI CM2. ATI protein content showed a low correlation with quality traits commonly analyzed in wheat breeding. Similarly, no trends were found regarding ATI content in wheat cultivars originating from numerous countries and decades of breeding history. Genome-wide association mapping revealed a complex genetic architecture built of many small, few medium and two major quantitative trait loci (QTL). The major QTL were located on chromosomes 3B for ATI 0.19-like and 6B for ATI 0.28, explaining 70.6 and 68.7% of the genotypic variance, respectively. Within close physical proximity to the medium and major QTL, we identified eight potential candidate genes on the wheat reference genome encoding structurally related lipid transfer proteins. Consequently, selection and breeding of wheat cultivars with low ATI protein amounts appear difficult requiring other strategies to reduce ATI content in wheat products.

Wheat amylase/trypsin inhibitors (ATIs): occurrence, function and health aspects

“…A number of studies have compared the amounts and composition of ATIs in different types of wheat with inconclusive results [8][9][10][11][12][13]. The presence and composition of ATIs is specific for the ploidy level of wheats and can be used to distinguish between diploid, tetraploid and hexaploid wheats [9,11].…”

“…3 A) [ 9 , 11 ] with no evidence for lower concentrations of ATIs in older types of bread wheat compared to modern high-yielding bread wheats (Fig. 3 B) [ 8 , 13 ]. There is wide variation in the amount of ATIs in bread wheats [ 12 , 13 ], but the genetic control is inconclusive being reported as high for Australian wheats [ 12 ], but low for European wheats [ 13 ].…”

“…3 B) [ 8 , 13 ]. There is wide variation in the amount of ATIs in bread wheats [ 12 , 13 ], but the genetic control is inconclusive being reported as high for Australian wheats [ 12 ], but low for European wheats [ 13 ]. The complex genetic architecture of ATIs indicates that it will be very difficult to select for cultivars with low ATI concentration using traditional breeding methods.…”

Absolute and relative quantitation of amylase/trypsin-inhibitors by LC-MS/MS from wheat lines obtained by CRISPR-Cas9 and RNAi

“…Furthermore, some durum wheat cultivars lack in monomeric 0.28 ( Geisslitz et al, 2020 ; Sielaff et al, 2021 ). Proteins with amylase and/or trypsin inhibitory activity are encoded by 38 genes in the hexaploid common wheat cultivar “Chinese Spring” showing the high complexity of the genetic architecture of ATIs ( Appels et al, 2018 ; Juhász et al, 2018 ; El Hassouni et al, 2021 ).…”

“…In the latter years, the development of novel sensitive and precise methods in combination with evaluation techniques has enhanced the analysis of proteins by proteomic-based methods. Indeed, the number of studies increased notably, which quantified ATIs in common wheat and other wheat species by targeted and untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) ( Henrottin et al, 2019 ; Bose et al, 2020 ; Geisslitz et al, 2020 ; Sagu et al, 2020 ; El Hassouni et al, 2021 ; Sielaff et al, 2021 ). These studies used different approaches, and studies comparing relative and absolute ATI quantitation approaches are very limited until now ( Geisslitz et al, 2018 ; Sielaff et al, 2021 ).…”