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Article Addendum
Na+- K+ transport in roots under salt stress
Isaac Zepeda-Jazo, Sergey Shabala, Zhonghua Chen and Igor I. Pottosin
volume 3 | issue 6
june 2008Pages: 401 - 403
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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
Isaac Zepeda-Jazo
Centro Universitario de Investigaciones Biomédicas; Universidad de Colima; Colima, México
Sergey Shabala
School of Agricultural Science; University of Tasmania; Hobart, Australia
Zhonghua Chen
School of Agricultural Science; University of Tasmania; Hobart, Australia
Igor I. Pottosin
Centro Universitario de Investigaciones Biomédicas; Universidad de Colima; Colima, México