[BojanaL]

Gluten is a plant protein. It provides elasticity, shape and chewy texture of pastas and other products made of plants containing gluten such as wheat, barley and ray. Prolamin and gluten are main wheat proteins (constitute 80% of total protein content). Plant uses those proteins as energy source during germination. They are equally good energy source for people. Wheat is a staple food for 20% of the people around the world. Gluten is especially important for vegetarians because plant proteins are only source of proteins for them. Besides being consumed directly, plant proteins are used as additives for numerous dietary products: to improve physical characteristic of the food, its consistency, texture, quantity…. Product labels usually contain information about gluten content. This protein is also used in cosmetic industry (hair and dermatology products) and in pet food production.

Gluten is important nutritional ingredient, but it is associated with couple of disorders that affect a lot of people around the globe. Those are wheat allergy, celiac disease and gluten sensitivity. Wheat allergy results from increased sensitivity toward some of the wheat proteins; it is manifested by nausea, urticaria, atopy… as a consequence of increased level of IgE and mast cells. Both prolamin and gluten might trigger allergy reaction, but gluten induced wheat allergy is more common. Gluten molecule is composed of gliadin and glutinen fractions. There are 9 subunits of low molecular weight glutinen that are known triggers of allergy reaction. When gluten sensitivity exists, body reacts to gliadin fraction by producing large amount of anti-gliadin antibodies (IgA and IgG). Symptoms of gluten sensitivity are bloating, diarrhea, stomach discomfort and pain. Gluten sensitivity is a less severe than celiac disease - severe autoimmune disorder of the small intestine. Celiac disorder can be confirmed through biopsy and blood analysis. Typical manifestations of celiac disease are fatigue, nausea and diarrhea, result of intestinal microvillus shortening. Disorder can develop at any time during the lifetime and so far, only solution for people diagnosed with celiac disease is strict gluten free diet. Between 0.5 and 1% of people in the USA and 22.4 million of people around the world are diagnosed with celiac disorder.

Gluten can be found everywhere, both in products that normally contain gluten (wheat and its products) and products that are boosted with gluten during industrial processing (yogurt, ice cream…). Due to increased rate of celiac disease in modern society, a lot of food companies oriented toward gluten free food production. While waiting for gluten free industry to develop, scientists are looking for a solution through genetic engineering of the plants. Team of international scientists recently published article on the latest achievement in this field, revealing that gluten free wheat is successfully created.

To obtain gluten free plant, scientists first had to identify mechanism of gluten production. This protein is essential nutrient during embryonal development. Gluten is produced after couple of genes are expressed. Enzyme that triggers expression of gluten associated genes is called DEMETER (DME). DME encodes 5-methylcytosine DNA glycosylase, enzyme responsible for transcriptional activation of gliadins and low molecular weight glutenins (via demethylation of their promoter site). When DME was suppressed by 85.6%, gluten production in the endosperm was decreased by 76.4%.

Study focused on DME homeologs sequences, their evolutionary changes, similarity between different plant species and potential silencing methods... Result was first gluten free plant. In the phylogenetic analysis, when DME sequences were compared between rice, Arabidopsis, barley, wheat and sorgum, it was shown that they are highly (evolutionary) conserved and homology between examined species proved to be high. DME homeologs are cytogenetically mapped in the barley and wheat (located on chromosome 5 in both species) and cloned. They are responsible for complex transcriptional regulation of gliadins and low molecular weight glutenins. Inverted repeats (known as hair pins) were used to “disable” DME expression. Result was decreased level of alpha, beta and gamma glutenins and glutadins in developing endosperm. Depending on the type of hair pin used and DME homeologs transformed, expression of different glutenins and glutadins family members were suppressed. Ideal plant would be one with completely knockout DME homeologs sequences, resulting in gluten 100% free seed. This is a goal for some future experiments.

After first gluten (almost) free plant is created, next step is assessment of its safety in transgenic mice, gluten sensitivity apes and finally in patients diagnosed with celiac disease.