Auxin Response in Arabidopsis under Cold Stress: Underlying Molecular Mechanisms
Auxin Response in Arabidopsis under Cold Stress: Underlying Molecular Mechanisms
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DOI：
10.1105/tpc.109.069906
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发表时间：
2009-12-01
期刊：
影响因子：
11.6
通讯作者：
Rahman, Abidur
中科院分区：
文献类型：
--
作者：
Shibasaki, Kyohei;Uemura, Matsuo;Rahman, Abidur
为了了解低温胁迫的机制基础和生长素反应的作用，我们对低温胁迫后拟南芥的根生长和重力反应进行了研究，发现在48℃下8-12h对根的生长和重力反应的抑制程度接近50%。生长素信号突变体AxR1和TIR1表现出减弱的重力反应，它们像野生型一样对冷处理做出反应，这表明冷胁迫影响生长素运输而不是生长素信号。一致地，生长素反应标记IAA2-GUS的表达分析和直接运输试验证实，寒冷抑制根基瓣(向下)的生长素运输。活细胞的显微镜观察显示，生长素外排载体PIN2的运输在寒冷条件下显著减少。PIN3的侧向再定位也受到了低温胁迫的抑制，PIN3被认为是介导根系重力反应的早期阶段。此外，寒冷对不同的蛋白质运输途径有不同的影响。此外，冷对蛋白质运输的抑制不依赖于细胞肌动蛋白的组织和膜的流动性。综上所述，这些结果表明，冷应激对生长素的影响与抑制生长素外排载体在细胞内的运输有关。
To understand the mechanistic basis of cold temperature stress and the role of the auxin response, we characterized root growth and gravity response of Arabidopsis thaliana after cold stress, finding that 8 to 12 h at 48 degrees C inhibited root growth and gravity response by similar to 50%. The auxin-signaling mutants axr1 and tir1, which show a reduced gravity response, responded to cold treatment like the wild type, suggesting that cold stress affects auxin transport rather than auxin signaling. Consistently, expression analyses of an auxin-responsive marker, IAA2-GUS, and a direct transport assay confirmed that cold inhibits root basipetal (shootward) auxin transport. Microscopy of living cells revealed that trafficking of the auxin efflux carrier PIN2, which acts in basipetal auxin transport, was dramatically reduced by cold. The lateral relocalization of PIN3, which has been suggested to mediate the early phase of root gravity response, was also inhibited by cold stress. Additionally, cold differentially affected various protein trafficking pathways. Furthermore, the inhibition of protein trafficking by cold is independent of cellular actin organization and membrane fluidity. Taken together, these results suggest that the effect of cold stress on auxin is linked to the inhibition of intracellular trafficking of auxin efflux carriers.