Monosaccharide Absorption Activity of Arabidopsis Roots Depends on Expression Profiles of Transporter Genes under High Salinity Conditions
Monosaccharide Absorption Activity of Arabidopsis Roots Depends on Expression Profiles of Transporter Genes under High Salinity Conditions
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DOI：
10.1074/jbc.m111.269712
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发表时间：
2011-12-16
影响因子：
4.8
通讯作者：
Yamaguchi-Shinozaki, Kazuko
中科院分区：
文献类型：
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作者：
Yamada, Kohji;Kanai, Motoki;Yamaguchi-Shinozaki, Kazuko
植物根系能够从根际吸收糖，但也释放糖和其他对生长和环境信号至关重要的代谢物。释放的糖分子的重吸收可以帮助减少通过根部的光合固定碳的损失。虽然生化分析已经揭示了单糖的吸收机制，在这一过程中所涉及的运输尚未得到充分的特点。在本研究中，我们证明，拟南芥STP 1和STP 13在根中的吸收过程中的单糖从根际发挥重要作用。在14个STP转运蛋白基因中，我们发现STP 1具有最高的转录水平，并且在正常条件下STP 1是单糖摄取的主要贡献者。相反，STP13被发现是由非生物胁迫诱导的，在正常条件下低表达。我们分析了STP 13在高盐条件下的根中的作用，在高盐条件下，表皮细胞的膜被破坏，我们检测到STP 13依赖的葡萄糖摄取量增加。此外，在高盐条件下，stp13突变体的葡萄糖流出量高于野生型植株。这些结果表明，STP13可以重吸收在高盐度条件下受损细胞释放的单糖。总体而言，我们的数据表明，在拟南芥根中的糖吸收能力的变化响应于环境压力，这种活动是依赖于糖转运蛋白的表达模式。
Plant roots are able to absorb sugars from the rhizosphere but also release sugars and other metabolites that are critical for growth and environmental signaling. Reabsorption of released sugar molecules could help reduce the loss of photosynthetically fixed carbon through the roots. Although biochemical analyses have revealed monosaccharide uptake mechanisms in roots, the transporters that are involved in this process have not yet been fully characterized. In the present study we demonstrate that Arabidopsis STP1 and STP13 play important roles in roots during the absorption of monosaccharides from the rhizosphere. Among 14 STP transporter genes, we found that STP1 had the highest transcript level and that STP1 was a major contributor for monosaccharide uptake under normal conditions. In contrast, STP13 was found to be induced by abiotic stress, with low expression under normal conditions. We analyzed the role of STP13 in roots under high salinity conditions where membranes of the epidermal cells were damaged, and we detected an increase in the amount of STP13-dependent glucose uptake. Furthermore, the amount of glucose efflux from stp13 mutants was higher than that from wild type plants under high salinity conditions. These results indicate that STP13 can reabsorb the monosaccharides that are released by damaged cells under high salinity conditions. Overall, our data indicate that sugar uptake capacity in Arabidopsis roots changes in response to environmental stresses and that this activity is dependent on the expression pattern of sugar transporters.