Background and aims: Uncontrolled uptake of Na+ is the reason that many species are sensitive to salinity. Suberin is a protective barrier found in the walls of root endodermal cells that appears to be important for salt tolerance, yet its specific protective mechanism has not been fully elucidated. Methods: Here we investigated the role of aliphatic suberin in protecting plants against salt stress by using a mutant of Arabidopsis, cyp86a1, which exhibits a significant reduction of root aliphatic suberin. Results: We found that NaCl significantly increased suberization in roots of hydroponic-grown wild-type plants, but not in cyp86a1. Cyp86a1 exhibited a salt-sensitive phenotype. Compared with wild-type, Na+ accumulation in shoots was higher in cyp86a1. We provide evidence that increased Na+ uptake was via the root transcellular pathway. Furthermore, cyp86a1 accumulated less K+ in shoots than wild-type under NaCl stress, which was a consequence of increased K+ efflux from the root vasculature. Additionally, we provide evidence that aliphatic suberin reduces inflow of water across the root endodermis under non-stress conditions but reduces the backflow of water to the medium under salt stress. Conclusions: Finally, we propose a model for the role of aliphatic suberin in restricting Na+ influx, K+ efflux and water backflow in plants under saline conditions.

Apoplastic barrier, Arabidopsis, CYP86A1, Root hydraulic conductivity (Lpr), Salt tolerance, Suberin
Plant and Soil
Department of Biology

Wang, P. (Pei), Wang, C.-M. (Chun-Mei), Gao, L. (Li), Cui, Y.-N. (Yan-Nong), Yang, H.-L. (Hai-Li), de Silva, N.D.G. (Nayana D. G.), … Wang, S.-M. (Suo-Min). (2020). Aliphatic suberin confers salt tolerance to Arabidopsis by limiting Na+ influx, K+ efflux and water backflow. Plant and Soil. doi:10.1007/s11104-020-04464-w