Characterization of AtSLAH4, a root anion cannel involved in net chloride uptake

Abstract

Although generally considered a toxic anion, we have shown that besides of an essential micronutrient, Chloride (Cl-) is a beneficial macronutrient (Franco-Navarro et al. 2016). Optimal growth of plants requires the synchronic supply of both Cl- and nitrate (NO3-) molecules, but salt stress causes excessive accumulation of Cl- in leaves, which can produce ion toxicity in Cl-sensitive crops such as citrus and grapevine. Apart from the control of stomatal closure, members of the SLAC/SLAH family of slow-type anion channels are involved in the regulation of NO3- and Cl- homeostasis in the root, including root-to-shoot transport and NO3- vs. Cl- discrimination according to environmental cues (Cubero-Font et al. 2016). AtSLAH3 mediates the loading of anions into xylem vessels, with a high discrimination of NO3- over Cl-. Under optimal growing conditions, high expression of AtSLAH1 and SLAH1/SLAH3 heteromerization increase by seven times the Cl- conductance of SLAH3. Salinity and water deficit abolish AtSLAH1 expression in an ABA-dependent manner, strongly reducing root-to-shoot translocation of Cl- under abiotic stress (Cubero-Font et al. 2016).

Cubero-Font, P (2017) PhD Thesis, Universidad de Sevilla, Seville, Spain Cubero-Font P, Maierhofer T, Jaslan J, Rosales Miguel A, Espartero J, Díaz-Rueda P, Müller Heike M, Hürter A-L, Al-Rasheid Khaled AS, Marten I, Hedrich R, Colmenero-Flores José M, Geiger D (2016). Current Biology 26 (16):2213-2220. doi:10.1016/j.cub.2016.06.045 Franco-Navarro JD, Brumos J, Rosales MA, Cubero-Font P, Talon M, Colmenero-Flores JM (2016). Journal of Experimental Botany 67(3): 873-891. doi:10.1093/jxb/erv502