Characterization of bread wheat starch mutants by transcriptome analyses targeted to grain metabolic pathways

Reserve starch, the major component of wheat kernel, consists of amylose and amylopectin. The variation in their ratio (about 1:3 in normal wheat) has a potential impact on the nutritional and technological properties of wheat-derived foods. Previously, three complete null lines of key starch biosynthesis genes (granule-bound starch synthase I, GBSSI; starch synthase IIa, SSIIa; starch branching enzyme IIa, SBEIIa) were generated in bread wheat and named Cad-GBSSI*, Cad-SSIIa*, and Cad-SBEIIa*, respectively (Botticella et al., 2018). The lines expressed novel kernel traits, including reduction in amylose content (by 100%, 54%, and 21%, respectively) and modification of resistant starch content, amylopectin/amylose ratio, seed hardness, and appearance. To refine the characterisation of starch metabolism and to bring out divergences underlying pleiotropic effects, morpho-anatomical and omics analyses were performed on Cad-GBSSI*, Cad-SSIIa* and Cad-SBEIIa* mutant kernels sampled at 25 days post anthesis and the results were compared to the wild type.