Coexpression of the maize delta-zein and beta-zein genes results in stable accumulation of delta-zein in endoplasmic reticulum-derived protein bodies formed by beta-zein.
Zeins, the major seed storage proteins of maize, are of four distinct types: alpha, beta, delta, and gamma. They are synthesized on the rough endoplasmic reticulum (ER) in a sequential manner and deposited in ER-derived protein bodies. We investigated the potential for producing sulfur-rich beta-zein and delta-zein proteins in leaf and seed tissues by expressing the corresponding genes in a constitutive manner in transgenic tobacco. The delta-zein and beta-zein, when synthesized individually, were stable in the vegetative tissues and were deposited in unique, zein-specific ER-derived protein bodies. Coexpression of delta-zein and beta-zein genes, however, showed that delta-zein was colocalized in beta-zein-containing protein bodies and that the level of delta-zein was fivefold higher in delta-/beta-zein plants than in delta-zein plants. We conclude that delta-zein interacts with beta-zein and that the interaction has a stabilizing effect on delta-zein.
Bagga
S
S
Agronomy and Horticulture Department, New Mexico State University, Las Cruces 88003, USA.
Adams
H P
HP
Rodriguez
F D
FD
Kemp
J D
JD
Sengupta-Gopalan
C
C
D004721:Endoplasmic Reticulum / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D014026:Nicotiana / Q000235:genetics / Q000648:ultrastructure; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism; D015028:Zein / Q000235:genetics*
D015028:Zein