Wheat supplies about 20% of the total food calories consumed worldwide and is a national staple in many countries. Besides being a key source of plant proteins, it is also a major cause of many dietinduced health issues, especially celiac disease. The only effective treatment for this disease is a total gluten-free diet. The present report describes an effort to develop a natural dietary therapy for this disorder by transcriptional suppression of wheat DEMETER (DME) homeologs using RNA interference. DME encodes a 5-methylcytosine DNA glycosylase responsible for transcriptional derepression of gliadins and low-molecular-weight glutenins (LMWgs) by active demethylation of their promoters in the wheat endosperm. Previous research has demonstrated these proteins to be the major source of immunogenic epitopes. In this research, barley and wheat DME genes were cloned and localized on the syntenous chromosomes. Nucleotide diversity among DME homeologs was studied and used for their virtual transcript profiling. Functional conservation of DME enzyme was confirmed by comparing the motif and domain structure within and across the plant kingdom. Presence and absence of CpG islands in prolamin gene sequences was studied as a hallmark of hypo-and hypermethylation, respectively. Finally the epigenetic influence of DME silencing on accumulation of LMWgs and gliadins was studied using 20 transformants expressing hairpin RNA in their endosperm. These transformants showed up to 85.6% suppression in DME transcript abundance and up to 76.4% reduction in the amount of immunogenic prolamins, demonstrating the possibility of developing wheat varieties compatible for the celiac patients.gluten intolerance | autoimmune reaction | prophylactic measure T he highly homologous seed storage proteins of wheat and barley dubbed as prolamins are classified on the basis of their physiochemical properties into alcohol-soluble gliadins and insoluble glutenins. The gliadins, based on their chemical composition and electrophoretic mobilities, are further classified into sulfur-poor ω-gliadins and the sulfur-rich α/β-and γ-gliadins (1). The corresponding proteins in barley are named as C-, γ-, B-, and D-hordeins (1). The complex mixture of these proteins also known as "gluten", in a single bread wheat variety, is comprised of up to 45 different gliadins, 7-16 low-molecular-weight glutenin (LMWg) subunits and 3-6 high-molecular-weight glutenin (HMWg) subunits (2). These proteins cumulatively represent 80% of proteins stored in wheat endosperm and constitute a major source of plant baseddietary proteins consumed worldwide (3). Despite wheat being the major source of dietary proteins, it is also a key determinant of many diet-induced health issues, especially gluten sensitivity, celiac sprue, schizophrenia, dermatitis herpetiformis, and IgE-mediated allergies including anaphylaxis (3-5). Among these disorders, celiac is one of the most common food-born enteropathies in humans, occurring in various frequencies around the globe (6). In addition to eliciti...

The prolamin peptides in wheat gluten and in the homologous storage proteins of barley and rye cause painful chronic erasure of microvilli of the small intestine epithelium in celiac patients. If untreated, it can lead to chronic diarrhea, abdominal distension, osteoporosis, weight-loss due to malabsorption of nutrients, and anemia. In addition to congenital cases, life-long exposure to gluten proteins in bread and pasta can also induce development of celiac sprue in adults. To date, the only effective treatment is life-long strict abstinence from the staple food grains. Complete exclusion of dietary gluten is, however, difficult due to use of wheat in many foods, incomplete labeling and social constraints. Thus, finding alternative therapies for this most common foodborne disease remained an active area of research, which has led to many suggestions in last few years. The pros and cons associated with these therapies were reviewed in the present communication. As different celiac patients are immunogenic to different members of the undigestible proline/glutamine rich peptides of ~149 gliadins and low molecular weight glutenin subunits as well as the six high molecular weight glutenin subunits, an exhaustive digestion of the immunogenic peptides in the stomach, duodenum, jejunum, and ileum of celiacs is required. In view of the above, we evaluated the capacity of cereal grains to synthesize and store the enzymes prolyl endopeptidase from Flavobacterium meningosepticum and the barley cysteine endoprotease B2, which in combination are capable of detoxifying immunogenic gluten peptides in a novel treatment of celiac disease.

Extensive application of imidazolinone (IMI) herbicides had a significant impact on barley productivity contributing to a continuous decline in its acreage over the last two decades. A possible solution to this problem is to transfer IMI-resistance from a recently characterized mutation in the ‘Bob’ barley AHAS (acetohydroxy acid synthase) gene to other food, feed and malting barley cultivars. We focused our efforts on transferring IMI-resistance to barley varieties adapted to the US Pacific Northwest (PNW), since it comprises ∼23% (335,000 ha) of the US agricultural land under barley production. To effectively breed for IMI-resistance, we studied the genetic diversity among 13 two-rowed spring barley cultivars/breeding-lines from the PNW using 61 microsatellite markers, and selected six barley genotypes that showed medium to high genetic dissimilarity with the ‘Bob’ AHAS mutant. The six selected genotypes were used to make 29–53 crosses with the AHAS mutant and a range of 358–471 F1 seeds were obtained. To make informed selection for the recovery of the recipient parent genome, the genetic location of the AHAS gene was determined and its genetic nature assessed. Large F2 populations ranging in size from 2158–2846 individuals were evaluated for herbicide resistance and seedling vigor. Based on the results, F3 lines from the six most vigorous F2 genotypes per cross combination were evaluated for their genetic background. A range of 20%–90% recovery of the recipient parent genome for the carrier chromosome was observed. An effort was made to determine the critical dose of herbicide to distinguish between heterozygotes and homozygotes for the mutant allele. Results suggested that the mutant can survive up to the 10× field recommended dose of herbicide, and the 8× and 10× herbicide doses can distinguish between the two AHAS mutant genotypes. Finally, implications of this research in sustaining barley productivity in the PNW are discussed.