Inducing adventitious root (AR) formation in mature walnut species ( L.) is challenging. However, the AR formation of mature trees can be improved by rejuvenation. In rejuvenated cuttings, exogenous indole-3-butyric acid (IBA) is essential for AR formation, and the underlying mechanism is still not well understood. Therefore, we utilized transcriptome sequencing to investigate the mechanism of IBA-induced AR formation. Our results revealed that, in comparison to the control group, IBA treatment (9 mM) significantly increased the endogenous indole-3-acetic acid (IAA) content, leading to an enhanced rooting rate. We performed RNA sequencing to identify differentially expressed genes (DEGs) between the IBA-treated and control (CK) groups at 1, 2, 3, and 5 days after cutting (DAC). The results showed that, compared to the control cuttings, there were 1 539, 889, 785, and 984 up-regulated genes and 2 791, 2 936, 3 017, and 1 752 down-regulated genes, at 1, 2, 3, and 5 DAC, respectively. Analysis of RNA-seq data revealed that (/) and (), associated with IBA transport, were down-regulated in the rejuvenation cuttings. In contrast, () and (), associated with auxin efflux, were up-regulated. We identified 49 ()-encoding genes, including , , , , , , , , and , which were up-regulated at 1–5 DAC in the rejuvenated cuttings. This study highlights that the overexpression of in poplar significantly enhance AR growth, as evidenced by increased root length, surface area, volume, and quantity. Moreover, the co-expression network analysis involving and in walnut cuttings elucidates complex genetic interactions, underscoring their pivotal role in the formation of AR. Our data supported the following molecular mechanism of IBA-induced adventitious root formation. Firstly, IBA is converted to free IAA in peroxisomes. Then, the highly concentrated IAA in the procambium and parenchyma cells induces

中文翻译：

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吲哚-3-丁酸诱导核桃软木插条不定根形成的转录组分析

在成熟核桃品种 (L.) 中诱导不定根 (AR) 形成具有挑战性。然而，成熟树木的 AR 形成可以通过复壮来改善。在复壮插条中，外源吲哚-3-丁酸（IBA）对于 AR 的形成至关重要，但其潜在机制仍不清楚。因此，我们利用转录组测序来研究IBA诱导AR形成的机制。我们的结果显示，与对照组相比，IBA 处理 (9 mM) 显着增加了内源性吲哚-3-乙酸 (IAA) 含量，从而提高了生根率。我们进行了 RNA 测序，以鉴定 IBA 处理组和对照 (CK) 组在切割 (DAC) 后 1、2、3 和 5 天时的差异表达基因 (DEG)。结果表明，与对照插穗相比，在1、2、3的时间点上调基因有1 539、889、785和984个，下调基因有2 791、2 936、3 017和1 752个。 、 和 5 个 DAC。RNA-seq 数据分析表明，与 IBA 运输相关的 (/) 和 () 在返壮插条中下调。相反，与生长素流出相关的 () 和 () 则上调。我们鉴定了 49 个 () 编码基因，包括 、 、 、 、 、 、 、 和 ，这些基因在返壮插条中在 1-5 DAC 处上调。这项研究强调，杨树中 的过度表达显着促进 AR 生长，根长、表面积、体积和数量的增加证明了这一点。此外，涉及核桃插条的共表达网络分析阐明了复杂的遗传相互作用，强调了它们在 AR 形成中的关键作用。我们的数据支持以下 IBA 诱导不定根形成的分子机制。首先，IBA 在过氧化物酶体中转化为游离 IAA。然后，原形成层和薄壁细胞中高浓度的 IAA 诱导