Mediating effect of auxin and PsYUC10B on petal abscission and flower longevity in tree peony exposed to high temperature

Abstract

Tree peony, valued for its ornamental and medicinal properties, is a renowned ornamental plant resource in China. However, its natural florescence is short, and high temperature often occur during this time, which can further reduce floral longevity. The short florescence significantly limits the advancement of the tree peony industry. Therefore, elucidating the regulatory mechanisms underlying flower senescence and petal abscission is crucial for developing strategies to extend floral longevity. This study investigated the regulatory roles of auxin in flower senescence and petal abscission, focusing specifically on the PsYUC10B gene in tree peony. The results revealed that the application of auxin delayed flower senescence and petal abscission. Conversely, high temperatures disrupted the auxin gradient across abscission zone and accelerated its formation. The differentially expressed PsYUC10B gene, which encodes a key enzyme in auxin biosynthesis, was obtained and identified in tree peony based on transcriptomic and proteomic data. Overexpression of PsYUC10B delayed flower senescence and petal abscission, while silencing PsYUC10B reduced floral lifespan. Additionally, silencing PsYUC10B resulted in a significant upregulation of genes encoding endoglucanase, polygalacturonase, pectin esterase, and hexokinase—enzymes involved in pectin and cellulose degradation—and a downregulation of chalcone synthase and L-ascorbate oxidase genes. Furthermore, heterologous expression of PsYUC10B in Arabidopsis confirmed its role in regulating petal abscission. These findings provide novel insights into the auxin pathway’s involvement in petal abscission and highlight PsYUC10B as a potential target for enhancing floral longevity in tree peony and other ornamental plants.