Gene editing for allergen amelioration in plants – A review

The aim of this review is to summarize current advancements in the application of CRISPR to ameliorate allergenicity in plant-based foods. The literature on food allergens highlights the negative impacts on quality of life for many sufferers. Efforts to select low-allergenicity crop varieties through conventional means have had limited success. Here we review the literature describing gene editing to eliminate allergenicity genes and measure subsequent allergen expression. Gene editing is a means of inserting or deleting nucleotides at precise locations/genes in the genome, and the most widely used technology is CRISPR (clustered regularly interspaced short palindromic repeats) along with an endonuclease such as Cas9 (CRISPR/Cas9). An example are the α-amylase/trypsin inhibitors (ATIs) in wheat that are responsible for bakers' asthma. CRISPR was utilized to simultaneously knock down two ATI subunits, resulting in reduced expression of both subunits. Between 1.4 % and 4.5 % of children suffer from peanut allergy. Progress toward knock down of expression of genes encoding known allergens in peanuts is reviewed. Other allergenic plant species of interest in this review are soy and mustard. Gene editing has the potential to manipulate expression of allergen genes to reduce allergenicity, but as some allergens play important roles in physiological processes such as biotic and abiotic stress amelioration, simply targeting their genes with CRISPR to abolish expression is not always feasible.