n nnnTo understand the mechanistic basis of cold temperature stressand the role of the auxin response, we characterized root growthand gravity response of Arabidopsis thaliana after cold stress,finding that 8 to 12 h at 4°C inhibited root growth andgravity response by 50%. The auxin-signaling mutants axr1 andtir1, which show a reduced gravity response, responded to coldtreatment like the wild type, suggesting that cold stress affectsauxin transport rather than auxin signaling. Consistently, expressionanalyses of an auxin-responsive marker, IAA2-GUS, and a directtransport assay confirmed that cold inhibits root basipetal(shootward) auxin transport. Microscopy of living cells revealedthat trafficking of the auxin efflux carrier PIN2, which actsin basipetal auxin transport, was dramatically reduced by cold.The lateral relocalization of PIN3, which has been suggestedto mediate the early phase of root gravity response, was alsoinhibited by cold stress. Additionally, cold differentiallyaffected various protein trafficking pathways. Furthermore,the inhibition of protein trafficking by cold is independentof cellular actin organization and membrane fluidity. Takentogether, these results suggest that the effect of cold stresson auxin is linked to the inhibition of intracellular traffickingof auxin efflux carriers.展开▼
机译:ABSTRACTn FONT> TH> TR> TABLE> n
n TOP n <字体颜色= 464c53>抽象 FONT> n 介绍 n 结果 n 讨论 n 方法 n 参考文献 n FONT> TH> TR> TABLE> n nnn要了解冷应力的机械基础 SUP>和t通过生长素反应的作用,我们表征了冷胁迫后拟南芥 I>的根生长 SUP>和重力反应, SUP>发现在4到8-12小时°C通过 50%抑制根生长和 SUP>重力响应。生长素信号突变体 axr1 I>和 SUP> tir1 I>表现出降低的重力响应,它们对冷的 SUP>处理如野生型,表明冷胁迫影响 SUP>植物生长素运输,而不是植物生长素信号传导。一致地,生长素反应性标志物 IAA2-GUS I>的表达 SUP>分析和直接 SUP>转运分析证实了寒冷抑制了根基基底 SUP>(向下)生长素运输。活细胞的显微镜显示 SUP>表明,低温下显着减少了生长素外排载体PIN2的运输,该载体在基层植物生长素的运输中起着 SUP>的作用。 SUP> PIN3的重新定位( SUP>被认为可以介导根重力响应的早期阶段)也受到冷胁迫的抑制 SUP>。此外,冷差异 SUP>影响了各种蛋白质运输途径。此外, SUP>受寒冷抑制的蛋白质运输与细胞肌动蛋白组织和膜流动性无关。综上所述,这些结果表明冷应激 SUP>对生长素的作用与抑制生长素外排载体的细胞内运输 SUP>有关。 > SUP>
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