Opaque1 encodes a myosin XI motor protein that is required for endoplasmic reticulum motility and protein body formation in maize endosperm.

摘要

Myosins are encoded by multigene families and are involved in many basic biological processes. However, their functions in plants remain poorly understood. Functional characterization of corn opaque1 (o1), which encodes a myosin XI protein, was carried out. o1 is a classic corn seed mutant with an opaque endosperm phenotype but a normal zein protein content. Compared with the wild type, o1 endosperm cells display dilated endoplasmic reticulum (ER) structures and an increased number of smaller, misshapen protein bodies. The O1 gene was isolated by map-based cloning and was shown to encode a member of the plant myosin XI family (myosin XI-I). In endosperm cells, the O1 protein is associated with rough ER and protein bodies. Overexpression of the O1 tail domain (the C-terminal 644 amino acids) significantly inhibited ER streaming in tobacco cells. Yeast 2-hybrid analysis suggested an association between O1 and the ER through a heat shock protein 70-interacting protein. It is concluded that O1 influences protein body biogenesis by affecting ER morphology and motility, ultimately affecting endosperm texture.