Poster: Salinity

Abs # 109: The Arabidopsis sodium transporter, AtHKT1 is an essential factor for salt tolerance and for reducing sodium accumulation in leaves.

Presenter:	Horie, Tomoaki , horie@biomail.ucsd.edu
Authors	Horie, Tomoaki  (A)   Maser, Pascal  (A)   Eckelman, Brendan  (A)   Uozumi, Nobuyuki  (B)   Schroeder, Julian I. (A)
Affiliations:	(A): University of California, San Diego (B): Graduate School of Bioagricultural Sciences, Nagoya University

Sodium (Na⁺) is toxic to most plants, but the molecular mechanisms of Na⁺ distribution among plant tissues remain largely unknown. The Arabidopsis HKT1 protein functions as a Na⁺ transporter. Growth assays and measurement of cation contents using athkt1 plants (T-DNA insertion lines) were performed with media with or without NaCl. Interestingly, athkt1 disruption rendered leaves Na⁺-hypersensitive in growth assays in plates and also in soil-grown mature plants watered once with 100 mM NaCl. athkt1plants exhibit higher Na⁺ levels in shoot and lower Na⁺ levels in roots than WT (Maser et al., 2002 FEBS letter). An AtHKT1 cDNA construct under the control of AtHKT1 promoter complemented Na⁺ hypersensitivity of athkt1 plants. New analyses of the role of AtHKT1 in vascular Na⁺ transport will be presented. Taken together, the wild type AtHKT1 transporter plays an important role in controlling root/shoot Na⁺ distribution and hence salt tolerance. The rice (Oryza sativa) HKT1 homologue is an AtHKT1-type sodium transporter. We have isolated oshkt1-mutant alleles and a novel phenotype will be presented.