EPIGENETIC AND POST-TRANSCRIPTIONAL ELIMINATION OF CELIAC-CAUSING WHEAT STORAGE PROTEINS

Rhoda Araba Tawiah Brew-Appiah

Celiac disease is an autoimmune condition caused by consumption of certain wheat, barley and rye grain storage proteins known as prolamins. In susceptible individuals, exposure to these proteins leads to a painful chronic erasure of the microvilli of the intestinal epithelium. At present, the only effective solution is a strict dietary abstinence from these prolamins. The aim of the current project was to develop `celiac-safe' wheat genotypes. With this goal in mind, first, a microspore transformation procedure for production of doubled haploid wheat transformants was optimized. The next step was to develop artificial microRNA (amiRNA) constructs for post-transcriptional silencing of the wheat DEMETER homoeologues identified as transcriptional activators of the immunogenic prolamins in the developing wheat endosperm. An alternative approach employing a `chimeric-hairpin' construct capable of producing multiple interfering RNAs corresponding with the transcripts of the prolamin super-family genes was also undertaken. The latter strategy required aligning the sequences of the wheat gliadins (/-, - and -types) and low molecular weight glutenins (LMWgs) available in the public domain. The alignment results allowed identification of five consensus sequences each representing a prolamin gene family, which were fused together to obtain the arms of the chimeric-hairpin. The amiRNA and chimeric-hairpin constructs were used in wheat transformation via electroporation of embryogenic microspores, and particle bombardment of scutellar calli in the varieties Louise, Hollis, WPB926, Farnum, Brundage 96 and Simon. Microspore transformation using the chimeric hairpin construct yielded 47 T2 transformants in Louise, Hollis, WPB926 and Farnum with sizable amounts of reductions in the content of immunogenic prolamins. Similarly, the 12 T2 lines characterized in the background of Brundage 96 obtained via particle bombardment of amiRNA constructs have shown reductions and specific-eliminations to variable degrees in the grain prolamin content. A compensatory increase in the amount of high molecular weight glutenins (HMWgs) was also observed in some cases, which is desirable for retaining end-use quality of the genotypes. These wheat transformants are intended for crossing with the aim of pyramiding their effects on prolamin content or composition, into a single wheat genotype. This will advance the goal of producing celiac-safe wheat cultivars.

EPIGENETIC AND POST-TRANSCRIPTIONAL ELIMINATION OF CELIAC-CAUSING WHEAT STORAGE PROTEINS

Files and links (1)

Abstract

Metrics

Details