Abstract
The endoplasmic reticulum (ER) body is an ER-derived organelle that is specific to Brassicales plants. In Arabidopsis thaliana, a transcription factor, NAI1, regulates the expression of PYK10, a beta-glucosidase of major ER body component, and NAI2, a novel ER body protein for ER body formation (1,2). We found that the co-expression of NAI2 and PYK10 is sufficient for ER body formation in onion (Allium cepa), a non Brassicales. These findings indicate that NAI2 and PYK10 is sufficient for the ER body formation. NAI1 regulates the expression of membrane of ER body 1 (MEB1) and MEB2. MEB1 and MEB2 are integral membrane proteins that localize to the ER body membrane. Depletion of NAI2 alters localization of MEB1 and MEB2, which become diffusely distributed within the ER network. The artificially induced ER bodies accumulate MEB2 in onion cells. These findings indicate that ER body components, NAI2 and PYK10, regulate ER body formation and localization of MEB2.
(1) Matsushima et al., (2004) Plant Cell. 16, 1536-1549.
(2) Yamada et al., (2008) Plant Cell. 20, 2529-2540.
