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
dx.doi.org/10.1007/s11104-020-04464-w
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