Effects of brassinosteroids on fruit growth and flavor quality of Zanthoxylum armatum DC. var . novemfolius at different harvest maturity stages

Abstract

Zanthoxylum armatum DC. var. novemfolius, a traditional medicinal and culinary plant, is known for its unique flavor and significant properties. However, its flavor and quality are negatively affected by premature harvest. Brassinosteroids (BR) are a group of important plant hormones that significantly affect fruit growth and development. Therefore, this study investigated the effects of exogenous BR on fruit flavor quality in Zanthoxylum armatum at six different maturity stages (days after flowering and pollination (DAF): F1 (45 DAF), F2 (60 DAF), F3 (75 DAF), F4 (90 DAF), F5 (105 DAF), and F6 (120 DAF)). Using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) analysis, we identified 58 volatile compounds, with terpenes and alcohols as the primary categories. Meanwhile, key findings demonstrate that BR treatment significantly increased the relative abundance of main flavor components and increased total sanshool content at the critical F3 stage, implying that after BR treatment, the F3 stage might be a key period for flavor formation in Zanthoxylum armatum fruit. Moreover, BR also enhanced morphological traits and quality-related indicators of Zanthoxylum armatum fruits during harvest maturity stages. Collectively, exogenous BR exerts positive effects on the flavor quality of Zanthoxylum armatum fruits during harvest maturity stages, with the most significant effect observed at the F3 stage. This study provides novel insights into BR-regulated aroma formation characteristics during Zanthoxylum armatum fruit maturity and highlights a theoretical basis for optimizing harvest strategies and improving the fruit quality of Zanthoxylum armatum.