title: Na-K transport in roots under salt stress.
abstract: Salinity causes billion dollar losses in annual crop production. So far, the main avenue in breeding crops for salt tolerance has been to reduce Na(+) uptake and transport from roots to shoots. Recently we have demonstrated that retention of cytosolic K(+) could be considered as another key factor in conferring salt tolerance in plants. A subsequent study has shown that Na(+)-induced K(+) efflux in barley root epidermis occurs primarily via outward rectifying K(+) channels (KORC). Surprisingly, expression of KORC was similar in salt- tolerant and sensitive genotypes. However, the former were able to better oppose Na(+)-induced depolarization via enhanced activity of plasma membrane H(+)-ATPase (thus minimizing K(+) leak from the cytosol). In addition to highly K(+)-selective KORC channels, activities of several types of non-selective cation channels were detected at depolarizing potentials. Here we show that the expression of one of them, NORC, was significantly lower in salt-tolerant genotypes. As NORC is capable of mediating K(+) efflux coupled to Na(+) influx, we suggest that the restriction of its activity could be beneficial for plants under salt stress.
authors.affiliation: Centro Universitario de Investigaciones Biomédicas; Universidad de Colima; Colima, México.
authors.forename: Isaac
authors.initials: I
authors.lastname: Zepeda-Jazo
authors.forename: Sergey
authors.initials: S
authors.lastname: Shabala
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Chen
authors.forename: Igor I
authors.initials: II
authors.lastname: Pottosin
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