Study Of Na~+, K~+Absorption And Accumulation In Arabidopsis Thaliana

Soil salinization is a serious threat to about one-third of the irrigated farmland, and it is one of the main cause of reducing harvests. Saline stress can lead to excessive accumulation of Na+in plants and disrupt the plants of ion homeostasis, inhibit the metabolism of cells, resulting in plant growth is restrained, even causing the death of plant. Different from high concentrations of Na+, K+is one of the main inorganic ions in higher plant cell, and plays an important role in the process of plant growth.Under salt stress, maintaining high K+concentration in the cytoplasm plays an important role in improving plant salt resistance. So the Study of Na+, K+absorption, transport and accumulation in Arabidopsis thaliana would contribute to clarify the mechanism of plant resistance to salt. In this research we used A. thaliana wild-type (WT), hkt1;1mutant (athkt1;1), sos1mutant (atsosl) and hkt1;1-sos1mutant (athkt1;1-sos1) as materials, with different concentration of K+, Na+treatment, Na+, K+concentration and Na+net uptake were analyzed. The results shows:1.Compared to WT, root Na+concentration and shoot K+concentration of athkt1;1reduce sharply, and it is not regulated by the Na+, K+content of liquid medium. According to the results, under salt stress, AtHKT1;1takes part in Na+unloading in the xylem, meanwhile influences K+transport indirectly.2.Under mild salt stress (25mM NaCl), root Na+concentration of atsosl increases, inversely shoot Na+, shoot K+and root K+concentration severely reduced, root Na+/K+incresaes inversely, and this process is not affected by the K+concentration of liquid medium; under severe salt stress (100mM NaCl), root Na+concentration of atsosl increases, inversely shoot K+and root K+concentration severely reduced. According to the results:AtSOS1mainly takes part in Na+loading in the xylem and Na+excreting from root to the external medium.3.Under mild salt stress, hkt1;1-sos1root Na+concentration has no significant difference with WT but is lower than atsosl, and the decrease of root K+is less than atsos1, and the root Na+/K+is lower than atsos1; Under2.5mM K+, the root Na+increase of athkt1;1-sos1is less than atsos1, while shoot and root concentration of K+has no significant differenc with WT but higher than atsos1. According to the results: compared to atsos1, the salt sensitivity of athkt1;1-sos1 mutations is relieved by reducing root Na+accumulation and increasing root K+accumulation.4.Compared to control (different concentration of NaCl treatment), the effects of10mM TEA+with different concentration of NaCl treatment on the absorption and accumulation of Na+, K+have no significant differences. Unlike the Suaeda maritima and Zygophyllum xanthoxylum, wild-type arabidopsis does not exist in the body of two low affinity Na+absorption way. The TEA+treatment significantly reduced the A. thaliana tissue water compared with the control,25,50,75,100,125,150mM NaCl treatment respectively reduced the tissue water by8%,19%,21%,31%,29%and40%. It is visible that10mM TEA+addition can significantly inhibit A. thaliana absorbing water.5. NaCl and KC1treatment can reduce the fresh weight, dry weight and tissue water of A. thaliana. Unlike other halophytes, there was no significant difference between the same concentrations of NaCl and KC1on the inhibition of wild type A. thaliana growth.