DataSheet_1_Transcriptomic and metabolomic analyses reveal the mechanism of uniconazole inducing hypocotyl dwarfing by suppressing BrbZIP39–BrPAL4 module mediating lignin biosynthesis in flowering Chinese cabbage.pdf

Uniconazole, a triazole plant growth regulator, is widely used to regulate plant height and prevent the overgrowth of seedlings. However, the underlying molecular mechanism of uniconazole in inhibiting the hypocotyl elongation of seedlings is still largely unclear, and there has been little research on the integration of transcriptomic and metabolomic data to investigate the mechanisms of hypocotyl elonga-tion. Herein we observed that the hypocotyl elongation of flowering Chinese cabbage seedings was significantly inhibited by uniconazole. Interestingly, based on combined transcriptome and metabolome analyses, we found that the “phenylpropanoid biosynthesis” pathway was significantly affected by uniconazole. In this pathway, only one member of the portal enzyme gene family, named BrPAL4, was remarkably downregulated, which was related to lignin biosynthesis. Furthermore, the yeast one-hybrid and dual-luciferase assays showed that BrbZIP39 could directly bind to the promoter region of BrPAL4 and activate its transcript. The virus-induced gene silencing system further demonstrated that BrbZIP39 could positively regulate hypocotyl elongation and the lignin biosynthesis of hypocotyl. Our findings provide a novel insight into the molecular regulatory mechanism of uniconazole inhibiting hypocotyl elongation in flowering Chinese cabbage and confirm, for the first time, that uniconazole decreases lignin content through repressing the BrbZIP39–BrPAL4 module-mediated phenylpropanoid biosynthesis, which leads to the hypocotyl dwarfing of flowering Chinese cabbage seedlings.

烯效唑（Uniconazole）是一种三唑类植物生长调节剂，被广泛用于调控株高、防止幼苗徒长。然而，烯效唑抑制幼苗下胚轴伸长的潜在分子机制仍未完全阐明，且目前针对整合转录组与代谢组数据探究下胚轴伸长机制的研究尚且较少。本研究发现，烯效唑可显著抑制菜心（flowering Chinese cabbage）幼苗的下胚轴伸长。有趣的是，联合转录组与代谢组分析结果显示，烯效唑显著影响了"苯丙烷类生物合成"通路。该通路中，仅1个名为BrPAL4的关键酶编码基因家族成员被显著下调，该基因与木质素生物合成相关。此外，酵母单杂交与双荧光素酶实验结果表明，BrbZIP39可直接结合BrPAL4的启动子区域并激活其转录。病毒诱导基因沉默（virus-induced gene silencing）系统进一步验证显示，BrbZIP39可正向调控下胚轴伸长及下胚轴的木质素生物合成。本研究结果为阐明烯效唑抑制菜心幼苗下胚轴伸长的分子调控机制提供了新视角，并首次证实：烯效唑通过抑制BrbZIP39–BrPAL4模块介导的苯丙烷类生物合成途径，降低了木质素含量，最终导致菜心幼苗下胚轴矮化。