The polarization of exocytosis in yeast and animals is assisted by the exocyst - an octameric vesicle tethering complex and an effector of Rab and Rho GTPases. Recently, the exocyst was described as a functional complex involved in morphogenesis also in plants. Hála et al. (2008) described involvement of exocyst complex in pollen tube growth and hypocotyls elongation in dark grown seedlings, Fendrych et al. (2010) uncovered key role of exocyst in cell plate formation, Kulich et al. (2010) emphasized the participation of exocyst in seed coat generation and Pečenková et al. (2011) described the contribution of exocyst subunits in plant defense towards the pathogens. All these processes are intimately linked to polarized secretion. Here we show involvement of exocyst in auxin efflux carriers PINs recycling. Using direct auxin transport measurement and GFP-tagged proteins, we showed that the exocyst is involved in recycling and polarization of PIN proteins and polar auxin transport regulation. Rootward polar auxin transport is compromised in loss-of-function mutants in exocyst subunits EXO70A1. On the cellular level we have detected small portion of PIN2:GFP in the "BFA-like" FM4-64 labelled compartments distinct from VHAa1 labeled endosoms. Moreover recycling of PIN1 and PIN2 is retarded in roots of...