The transcriptomic and metabolomic profiles of E. californica revealed pathways related to drought stress response and close association with alkaloid biosynthesis.

Understanding the adaptability of plants to the environment will help us address the challenges posed by the constantly changing climate to sustainable agriculture and industry. The California poppy (Eschscholzia californica Cham.) of Papaveraceae is an ornamentally and medicinally valuable plant species, not only due to its beautiful flower, but also the strong abiotic stress tolerance and production of pharmacologicallly active alkaloids. However, little is known about the mechanisms of its drought tolerance and association with the alkaloids biosynthesis. In this study, significant morphological and physiological changes of E. californica under early and late drought stress were found. Subsequently, the transcriptomic and metabolomic dynamics between normal and drought conditions were independently and jointly analyzed. Transcriptome analysis identified 24,176 differentially expressed genes (DEGs), which were enriched in alkaloid biosynthesis, phytohormone synthesis and signal transduction pathways, amino acid biosynthesis, and reactive oxygen species scavenging, etc. A large number of DEGs encoding transcription factor represent a reservoir for transcriptional regulation of drought stress responses of E. californica. Metabolomic analysis detected 393 drought responsive differentially expressed metabolites (DEMs), predominant in alkaloids and phenolic acids. Consistency between DEGs and DEMs identified by joint analysis revealed critical pathways in response to drought in E. californica and its close association with alkaloid biosynthesis. This study provides new insights into the drought response mechanisms of E. californica. The contribution of alkaloids to drought tolerance is particularly worthy of further in-depth research. [Display omitted] • The first transcriptomic and metabolomic study of drought response in E. californica. • Essential pathways responding to drought were identified in E. californica. • Drought stress promotes biosynthesis of alkaloid , especially isoquinoline alkaloids. • A large number of drought responsive transcription factors were identified. [ABSTRACT FROM AUTHOR]