Effects of TaMTL-Edited Mutations on Grain Phenotype and Storage Component Composition in Wheat

Wheat nutrition and processing-quality are primarily based on the endosperm ingredients. However, the effect of embryos on grain traits and components remains unclear. In this study, we found that in the cross-pollinated and self-pollinated progenies of the four wheat mtl mutants (mtl-A, mtl-AD, mtl-BD, and mtl-ABD) the haploid induction rates were 0-15.6% and 0-14.1%, and the embryo abortion rates were 0-27.4% and 0-24.1%, respectively, in which mtl-A had no effect on haploid induction and embryo development. The embryoless grains (ELG) were comparable to the normal grains (NG) from mtl-AD, mtl-BD, and mtl-ABD in grain length, grain width and thousand-kernel weight, but the grain traits were significantly less than those in NG from mutant mtl A. During grain filling period, mtl ABD had similar ELG ratio and amount of starch granule (SG) and protein body (PB) in ELG and NG. At maturity stage, the morphological features of A-type and B-type SG in ELG were similar to those in NG in mtl mutants; however, amylose, gliadin, and glutenin contents were higher in ELG, and total starch, albumin and globulin contents were higher in NG. Our results clarified the effect of the wheat mtl mutants on haploid induction and grain traits and nutrition composition in this crop, and provided new clues for studying the development of embryo and endosperm and their interaction in plants.