Integrative physiological, metabolomic, and transcriptomic insights into strawberry adaptation to boron deficiency...

Boron (B) is an essential micronutrient for plant growth, with a narrow range between deficiency and toxicity. Strawberry is highly sensitive to boron deficiency (BD), which severely impacts its growth and yield. However, the physiological and molecular mechanisms underlying strawberry's response to BD stress remain poorly understood. In this study, we employed an integrated physiological, metabolomic, and transcriptomic approach to investigate these mechanisms. Our results demonstrate that BD stress significantly inhibits strawberry growth by inducing oxidative damage, disrupting photosynthetic efficiency, and altering phytohormonal homeostasis. Multi-omics analyses revealed a substantial redirection of metabolic flux within the phenylpropanoid pathway. This was characterized by the downregulation of genes such as HIDH, DFR, ANS, and ANR, leading to reduced accumulation of isoflavones (e.g., genistin) and specific flavanols (e.g., epigallocatechin). Concurrently, the observed upregulation of CHI and the accumulation of flavonols like rutin and quercetin 3-sambubioside suggest an adaptive enhancement of the antioxidant system to mitigate oxidative stress. Furthermore, BD stress extensively perturbed phytohormone biosynthesis and signaling pathways (e.g., AUX1, ARRs, PP2C, ERF1/2) and primary metabolism, including amino acid biosynthesis (e.g., ilvD, ilvE, aroD). These findings provide a comprehensive metabolite and gene-level perspective on the adaptive strategies of strawberry to BD stress, offering valuable insights and potential biomarkers for breeding boron-efficient strawberry varieties.