• Rice coleoptile elongation under submergence guarantees fast seedling establishment in the field. We investigated the role of auxin in influencing the capacity of rice to produce a long coleoptile under water.
• In order to explore the complexity of auxin's role in coleoptile elongation, we used gene expression analysis, confocal microscopy of an auxin‐responsive fluorescent reporter, gas chromatography coupled to tandem mass spectrometry (GC–MS/MS), and T‐DNA insertional mutants of an auxin transport protein.
• We show that a higher auxin availability in the coleoptile correlates with the final coleoptile length under submergence. We also identified the auxin influx carrier AUX1 as a component influencing this trait under submergence. The coleoptile tip is involved in the final length of rice varieties harbouring a long coleoptile.
• Our experimental results indicate that auxin biosynthesis and transport underlies the differential elongation between short and long coleoptile‐harbouring japonica rice varieties.

中文翻译：

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淹没下粳稻的长胚芽鞘性状需要生长素。

• 浸没条件下水稻胚芽鞘的延伸保证了田间快速建立苗木。我们研究了生长素在影响水稻在水下产生长胚芽鞘的能力中的作用。
• 为了探讨生长素在胚芽鞘延长中的作用的复杂性，我们使用了基因表达分析，生长素反应性荧光报告分子的共聚焦显微镜，气相色谱-串联质谱（GC-MS / MS）和T-DNA插入突变体生长素转运蛋白。
• 我们表明，胚芽鞘中较高的生长素可用性与浸没时的最终胚芽鞘长度相关。我们还确定了生长素流入载体AUX1是浸入水中影响此性状的组分。胚芽鞘尖端涉及具有长胚芽鞘的水稻品种的最终长度。
• 我们的实验结果表明，生长素的生物合成和运输是短和长鞘翅目粳稻品种之间差异伸长的基础。