Kian Hématy, Damien De Bellis, Xin Wang, Ari Pekka Mähönen, Niko Geldner.
Analysis of exocyst function in endodermis reveals its widespread contribution and specificity of action.
Plant Physiology, 2022;, kiac019, https://doi.org/10.1093/plphys/kiac019
Abstract
The exocyst is the main plasma membrane vesicle-tethering complex in eukaryotes and is composed of eight different subunits. Yet, in plant genomes, many subunits display multiple copies, thought to reflect evolution of complex subtypes with
divergent functions. In Arabidopsis thaliana root endodermal cells, the isoform EXO70A1 is required for positioning of
CASP1 at the Casparian Strip Domain, but not for its non-targeted secretion to the plasma membrane. Here, we show that
exo84b resembles exo70a1 mutants regarding CASP1 mistargeting and secretion of apoplastic proteins, but exo84b additionally affects secretion of other integral plasma membrane proteins. Moreover, conditional, cell-type-specific gene editing of
the single-copy core component SEC6 allows visualization of secretion defects in plant cells with a complete lack of exocyst
complex function. Our approach opens avenues for deciphering the complexity/diversity of exocyst functions in plant cells
and enables analysis of central trafficking components with lethal phenotypes.