Characterizing seed dormancy in Epimedium brevicornu Maxim.: Development of novel chill models and determination of dormancy release mechanisms by transcriptomics

Abstract Purpose: Epimedium brevicornu Maxim. is a perennial persistent C3 plant of the genus Epimedium Linn. in the family Berberaceae that exhibits severe physiological and morphological seed dormancy. We placed mature E.brevicornu seeds under nine stratification treatment conditions and explored the mechanisms of influence by combining seed embryo growth status assessment with related metabolic pathways and gene co-expression analysis. Results: We identified 3.9 °C as the optimum cold-stratification temperature of E.brevicornu seeds via a chilling unit (CU) model. The best treatment was variable-temperature stratification (10/20 °C, 12/12 h) for 120 d followed by low-temperature stratification (4 °C) for 90 d. A total of 63801 differentially expressed genes were annotated to 2587 transcription factors (TFs) in 17 clusters in two comparisons. Genes specifically highly expressed in the dormancy release treatment group were significantly enriched in embryo development ending in seed dormancy and fatty acid degradation, indicating the importance of these two processes. Coexpression analysis implied that the TF GRF had the most reciprocal relationships with genes, and multiple interactions centered on zf-HD and YABBY as well as on MYB, GRF, and TCP were observed. Conclusion: In this study, analyses of plant hormone signal pathways and fatty acid degradation pathways revealed changes in key genes during the dor- mancy release of E.brevicornu seeds, providing evidence for the filtering of E.brevicornu seed dormancy-related genes.