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

Abstract

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 (α/β/β'/γ/δ/ε/ζ). In Arabidopsis two genes coding for the β-COP subunit have been identified, which are the result of recent tandem duplication. Here we have used a lossof-function approach to study the function of β-COP. The results we have obtained suggest that β-COP is required for plant growth and salt tolerance. In addition, β-COP function seems to be required for maintaining the structure of the Golgi apparatus.

Critical Determinants in ER-Golgi Trafficking of Enzymes Involved in Glycosylation

“…In plant cells, the COPII and COPI-coated cargo carriers’ transportation impacts plant growth, stress response, and protein transportation. In A.thaliana , multiple paralogs of COPI components have been discovered [ 49 , 50 ]. The silencing of the β 1/2-COP gene enhanced the sensitivity of A.thaliana to salt stress [ 49 , 51 ].…”

“…In A.thaliana , multiple paralogs of COPI components have been discovered [ 49 , 50 ]. The silencing of the β 1/2-COP gene enhanced the sensitivity of A.thaliana to salt stress [ 49 , 51 ]. Double mutant of β 1/2-COP and a single mutant of α 2-COP were dwarfed compared to Col-0 [ 49 , 52 ], and the silencing of β 1/2-COP or α 2-COP or p24 protein altered the structure of the Golgi [ 49 , 52 , 53 ].…”

“…The silencing of the β 1/2-COP gene enhanced the sensitivity of A.thaliana to salt stress [ 49 , 51 ]. Double mutant of β 1/2-COP and a single mutant of α 2-COP were dwarfed compared to Col-0 [ 49 , 52 ], and the silencing of β 1/2-COP or α 2-COP or p24 protein altered the structure of the Golgi [ 49 , 52 , 53 ]. The knockout of α 1-COP, γ -COP, and ε -COP resulted in a reduction in seed production due to altered pollen grain adherence and pollen tube germination [ 54 ].…”

Differential Involvement of Arabidopsis β’-COP Isoforms in Plant Development

“…In addition, β'2β'3-cop-1 (containing β'3-cop-1, down for β'3-COP) was also used to compare with β'1β'3-cop-1 (containing β'3-cop-1, down for β'3-COP), the only homozygous line obtained for the crosses β'1-cop x β'3-cop. We have shown previously that depletion of β-COP compromises tolerance to NaCl and KCl in Arabidopsis [32,33]. Therefore, we decided to test whether β'2β'3-cop-2, which has a wild-type phenotype under standard growth conditions, also showed enhanced sensitivity to NaCl and KCl, using the range of NaCl and KCl concentrations used in our previous studies with β-cop mutants [32,33].…”

“…Besides, mutants in plant COPI subunits have been shown to have an altered Golgi morphology, which highlights the importance of COPI function for Golgi structure [27,28,30,31]. Loss of COPI function has also been shown to affect tolerance to salt stress, in particular to chloride ions, possibly due to mislocalization or reduced activity of chloride channels/transporters [32,33]. Here we have used a lossof-function approach to analyze the possible function of the three paralogs of the β'-COP subunit in Arabidopsis.…”