Loss of Arabidopsis β-COP Function Affects Golgi Structure, Plant Growth and Tolerance to Salt Stress

The early secretory pathway involves bidirectional transport between the endoplasmic reticulum (ER) and the Golgi apparatus and is mediated by coat protein complex I (COPI)-coated and coat protein complex II (COPII)-coated vesicles. COPII vesicles are involved in ER to Golgi transport meanwhile COPI vesicles mediate intra-Golgi transport and retrograde transport from the Golgi apparatus to the ER. The key component of COPI vesicles is the coatomer complex, that is composed of seven subunits (alpha/beta/beta'/gamma/delta/epsilon/zeta). In Arabidopsis two genes coding for the beta-COP subunit have been identified, which are the result of recent tandem duplication. Here we have used a loss-of-function approach to study the function of beta-COP. The results we have obtained suggest that beta-COP is required for plant growth and salt tolerance. In addition, beta-COP function seems to be required for maintaining the structure of the Golgi apparatus.