Differences in gluten protein composition between old and modern durum wheat genotypes in relation to 20th century breeding in Italy

TLDR

While 20th‑century wheat breeding has been well studied for yield, its effects on gluten protein composition remain poorly understood. The study compared old and modern Italian durum wheat genotypes grown in Mediterranean conditions to assess breeding impacts on gluten quality for processing and health. The authors evaluated glutenin and gliadin subunit composition and expression in these genotypes, comparing the results between the two groups. Modern varieties showed superior technological performance due to superior HMW‑ and LMW‑glutenin alleles and higher glutenin/gliadin ratios, while α/γ gliadins were unchanged, ω‑5 gliadin expression was markedly reduced, and lower rainfall during grain filling correlated with increased HMW‑GS and ω‑gliadins, indicating that 20th‑century breeding improved both gluten quality and allergenic potential.

Abstract

The impact of breeding on grain yields of wheat varieties released during the 20th century has been extensively studied, whereas less information is available on the changes in gluten quality associated with effects on the amount and composition of glutenins and gliadins. In order to explore the effects of breeding during the 20th century on gluten quality of durum wheat for processing and health we have compared a set of old and modern Italian genotypes grown under Mediterranean conditions. The better technological performance observed for the modern varieties was found to be due not only to the introgression of superior alleles of high (HMW-GS) and low molecular weight (LMW-GS) glutenin subunits encoded at Glu-B1 and Glu-B3 loci, but also to differential expression of specific storage proteins. In particular, the higher gluten index observed in modern genotypes was correlated with an increased glutenin/gliadin ratio and the expression of B-type LMW-GS which was, on average, two times higher in the modern than in the old group of durum wheat genotypes. By contrast, no significant differences were found between old and modern durum wheat genotypes in relation to the expression of α-type and γ-type gliadins which are major fractions that trigger coeliac disease (CD) in susceptible individuals. Furthermore, a drastic decrease was observed in the expression of ω-type gliadins in the modern genotypes, mainly ω-5 gliadin (also known as Tri a 19) which is a major allergen in wheat dependent exercise induced anaphylaxis (WDEIA). Immunological and 2DE SDS-PAGE analyses indicated that these differences could be related either to a general down-regulation or to differences in numbers of isoforms. Lower rainfall during grain filling period was related to overall higher expression of HMW-GS and ω-gliadins. In conclusion, breeding activity carried out in Italy during the 20th century appears to have improved durum wheat gluten quality, both in relation to technological performance and allergenic potential.