Functional analysis of TaPDI genes on storage protein accumulation by CRISPR/Cas9 edited wheat mutants

Wheat protein disulfide isomerase (PDI) is involved in the formation of glutenin macropolymers (GMP) and the correct folding and accumulation of storage proteins in endosperm. In present study, seven types of homozygous TaPDI gene edited mutants were obtained by CRISPR/Cas9 technology, which were confirmed by PCR-RE and sequencing. Compared with other mutants and wild type (WT), the grain length and width in mutant PDI-abd-6 which was edited for the three TaPDI homoeologous genes were reduced, and the grain middle parts were slumped. The GMP size in PDI-abd-6 was not significantly different from that in WT, whereas the accumulation of protein bodies (PBs) increased during grain development. The endosperm cells became denser in PDI-abd-6 without sheet-like structure, and the expression level of TaBiP gene was significantly decreased. Particularly, the GMP content in PDI-abd-6 is also decreased significantly. The basic bread and flour rheological parameters in the mutant were negatively changed compared with those in WT. Our results indicated that TaPDI genes affects wheat flour-processing quality by the order of TaPDI-4B, TaPDI-4D, and TaPDI-4A from high to low; the expression of either one TaPDI could be enough to maintain the GMP accumulation and processing properties of wheat dough.