Expression of a mutant α-zein creates the floury2 phenotype in transgenic maize

摘要

The maize floury2 mutation results in the formation of a soft, starchy endosperm with a reduced amount of prolamin (zein) proteins and twice the lysine content of the wild type. The mutation is semidominant and is associated with small, irregularly shaped protein bodies, elevated levels of a 70-kDa chaperone in the endoplasmic reticulum, and a novel 24-kDa polypeptide in the zein fraction. The 24-kDa polypeptide is a precursor of a 22-kDa -zein protein that is not properly processed. The defect is due to an alanine-to- valine substitution at the C-terminal position of the signal peptide, which causes the protein to be anchored to the endoplasmic reticulum.