The growth and development of lateral roots (LRs) determine the nutrient absorption and environmental adaptability of tea plant, playing a crucial role in the economic efficiency of tea plantations. However, the molecular mechanisms underlying the formation of LRs in tea plant remain unreported. In this study, we established a LRs induction system in tea plants by exogenously adding N-1-naphthylphthalamic acid (NPA) and naphthaleneacetic acid (NAA). The molecular mechanisms of LRs formation were analyzed through transcriptomics and endogenous hormone measurements. Results showed that NAA treatment could counteract the inhibitory effect of NPA on LRs formation and promote the generation of LRs in tea plant. The addition of exogenous NAA reduced the levels of auxin and zeatin in the root tips while increasing the content of abscisic acid (ABA). Transcriptomic analysis at four time points (2, 6, 12, and 24 h) after NAA vs. MOCK treatment revealed 78 different expression genes (DEGs) associated with plant hormone signaling pathways. Among these, the auxin signaling pathway was the most significant in responding to the LRs formation in tea plant. Weighted Gene Co-Expression Network Analysis (WGCNA) identified the Mitogen-Activated Protein Kinases (MAPK) signaling pathway as responsive to NAA treatment, participating in the formation of LRs in tea plant. This study provides potential signaling pathways for the investigation of LRs formation in tea plant and identifies candidate genes for further research into tea plant root system architecture (RSA).

中文翻译：

---

转录组和植物激素的联合分析为茶树 （Camellia sinensis） 侧根形成的信号机制提供了新的见解


侧根 （LRs） 的生长发育决定了茶树的养分吸收和环境适应性，对茶园的经济效率起着至关重要的作用。然而，茶树中 LRs 形成的分子机制仍未报道。在这项研究中，我们通过外源添加 N-1-萘基邻苯二甲酸 （NPA） 和萘乙酸 （NAA） 在茶树中建立了 LRs 诱导系统。通过转录组学和内源性激素测量分析 LRs 形成的分子机制。结果表明，NAA 处理可以抵消 NPA 对 LRs 形成的抑制作用，促进茶树 LRs 的生成。外源 NAA 的添加降低了根尖中生长素和玉米素的水平，同时增加了脱落酸 （ABA） 的含量。NAA 与 MOCK 处理后 4 个时间点 （2 、 6 、 12 和 24 小时） 的转录组学分析揭示了与植物激素信号通路相关的 78 个不同表达基因 （DEGs）。其中，生长素信号通路对茶树 LRs 形成的响应最为显著。加权基因共表达网络分析 （WGCNA） 确定丝裂原活化蛋白激酶 （MAPK） 信号通路对 NAA 处理有反应，参与茶树中 LRs 的形成。本研究为研究茶树中 LRs 的形成提供了潜在的信号通路，并为进一步研究茶树根系结构 （RSA） 确定了候选基因。