1,9-decanediol (1,9-D) is a biological nitrification inhibitor secreted in roots, which effectively inhibits soil nitrifier activity and reduces nitrogen loss from agricultural fields. However, the effects of 1,9-D on plant root growth and the involvement of signaling pathways in the plant response to 1,9-D have not been investigated. Here, we report that 1,9-D, in the 100–400 μM concentration range, promotes primary root length in Arabidopsis seedlings at 3d and 5d, by 10.1%–33.3% and 6.9%–32.6%, and, in a range of 50–200 μM, leads to an increase in the number of lateral roots. 150 μM 1,9-D was found optimum for the positive regulation of root growth. qRT-PCR analysis reveals that 1,9-D can significantly increase AtABA3 gene expression and that a mutation in ABA3 results in insensitivity of root growth to 1,9-D. Moreover, through pharmacological experiments, we show that exogenous addition of ABA (abscisic acid) with 1,9-D enhances primary root length by 23.5%–63.3%, and an exogenous supply of 1,9-D with the ABA inhibitor Flu reduces primary root length by 1.0%–14.3%. Primary root length of the pin2/eir1-1 is shown to be insensitive to both exogenous addition of 1,9-D and ABA, indicating that the auxin carrier PIN2/EIR1 is involved in promotion of root growth by 1,9-D. These results suggest a novel for 1,9-D in regulating plant root growth through ABA and auxin signaling.

1,9-癸二醇（1,9-D）是根系分泌的生物硝化抑制剂，能有效抑制土壤硝化菌活性，减少农田氮素流失。然而，尚未研究 1,9-D 对植物根系生长的影响以及植物对 1,9-D 反应中信号通路的参与。在这里，我们报告说，在 100–400 μM 浓度范围内，1,9-D 在第 3 天和第 5 天促进拟南芥幼苗的主根长度，分别增加 10.1%–33.3% 和 6.9%–32.6%，并且在一定范围内50-200 μM，导致侧根数量增加。发现 150 μM 1,9-D 最适合根系生长的正向调节。qRT-PCR 分析显示 1,9-D 可以显着增加AtABA3基因表达以及 ABA3 中的突变导致根系生长对 1,9-D 不敏感。此外，通过药理学实验，我们表明外源添加 ABA（脱落酸）和 1,9-D 可使初生根长度增加 23.5%–63.3%，并且外源供应 1,9-D 和 ABA 抑制剂 Flu 可减少主根长度增加 1.0%–14.3%。pin2/eir1-1的初生根长度对外源添加 1,9-D 和 ABA 均不敏感，表明生长素载体 PIN2/EIR1 参与了 1,9-D 对根系生长的促进作用。这些结果表明 1,9-D 通过 ABA 和生长素信号调节植物根系生长的新方法。