Assessing drought stress response in low-gliadin wheat developed via RNAi and CRISPR/Cas

The gluten proteins are responsible for the visco-elastic properties of flour, but they also trigger the immune response in celiac disease patients. For that reason, low-gliadin RNA interference (RNAi) and CRISPR bread and durum wheat lines were generated in previous works. This study evaluated their drought stress response during the post-anthesis stage through gene expression and protein analyses. A drought-sensible durum wheat variety and the drought-tolerant landrace Aoujia were compared to the RNAi and CRISPR/Cas lines under the same conditions. The severe water stress treatment consisted of 25% field capacity (FC) applied three days after anthesis (DAA), while the 100% FC was set as control conditions. The expression levels of genes encoding enzymes (CAT and GPX), an enzyme involved in proline biosynthesis (P5CR), and galactinol synthase gene (GolS1) were assessed in response to drought stress. All the lines showed an increase of GPX, GolS1 and P5CR expression under drought. Particularly, Aouija and the D793 RNAi line had the greatest CAT, P5CR, and GolS1 expression compared to the others. Notably, some low-gliadin lines showed an overexpression of drought-related genes even under control conditions, possibly due to pleiotropic effects on other genes. The low-gliadin lines exhibited responses comparable to, or better than, their wild relatives, indicating an unaltered or improved stress response. Regarding the prolamins accumulation, RNAi and CRISPR lines retained low-gliadin content under severe drought, contrary to the wild-type lines, which increased their gliadin content drastically. This indicated the strong stability of the low-gliadin nature of these lines.