Kiwifruit is popular among consumers, but its roots are sensitive to the surrounding environment and cannot efficiently use water and nutrients, leading to weak plant growth and relatively lower fruit yield and quality. Although brassinosteroid (BR) plays a critical role in promoting kiwifruit root growth, its regulatory mechanism is still unclear. Here we reported the inhibition of root growth at the physiological level when endogenous brassinosteroid level was reduced by its biosynthesis inhibitor brassinazole (BRZ), whereas exogenous application of BR increased root elongation and lateral root and root hair growth. Genome-wide transcriptome analysis results indicated that BR and BRZ altered the expression levels of some genes in kiwifruit roots. The data show that BR promotes root development by regulating genes involved in auxin signal transduction. Our study demonstrates the important role of BR in kiwifruit root growth.

猕猴桃深受消费者喜爱，但其根系对周围环境敏感，不能有效利用水分和养分，导致植株生长较弱，果实产量和品质相对较低。尽管油菜素类固醇（BR）在促进猕猴桃根系生长中起着关键作用，但其调控机制仍不清楚。在这里，我们报告了当内源性油菜素类固醇水平被其生物合成抑制剂芸苔素唑 (BRZ) 降低时，在生理水平上对根生长的抑制，而外源施用 BR 增加了根伸长和侧根和根毛生长。全基因组转录组分析结果表明 BR 和 BRZ 改变了猕猴桃根中某些基因的表达水平。数据表明，BR通过调节参与生长素信号转导的基因来促进根发育。我们的研究证明了 BR 在猕猴桃根系生长中的重要作用。