Huan Guan ¹ Yuhuan Zhao ¹ Qing Chen ² Qianqian Zhang ¹ Pengpeng Yang ¹ Shuying Sun ^1* Guilin Chen ^1*

• ¹ Inner Mongolia University, Hohhot, China
• ² University of Science and Technology of China fellow, Hefei, China

Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao (AMM) is an important medicinal plant that is used for both medicine and food. It is widely used in East Asia and South Asia. It is normally cultivated by transplanting annual rhizomes. Understanding the dormancy of underground buds of AMM is essential for its harvest and transplantation. Despite the thorough research on the dormancy of bud in perennial woody plants, perennial herbs, and especially medicinal plants, such as AMM, have been rarely studied. We analyzed the transcriptome and non-targeted metabolome of dormant buds stage-by-stage to investigate the regulatory mechanism of the transition of endo- to ecodormancy. A total of 1069 differentially accumulated metabolites (DAMs) were identified, which participated in amino acid metabolism and carbohydrate metabolism. Transcriptome analysis revealed a total of 16832 differentially expressed genes (DEGs). Functional enrichment analysis indicated that carbohydrate metabolism, hormone signaling pathways, and amino acid metabolism contributed to the transition from endo- to ecodormancy. The starch and sucrose metabolism and hormone signaling pathways were mainly analyzed in the transition between different dormancy states. During the transition from endo- to ecodormancy, the highest content of indole-3-acetic acid (IAA) and the most DEGs enriched in the IAA signaling pathway demonstrate that IAA may play a key role in this process. We obtained the candidate genes through co-expression network analysis, such as BGL, GN, glgC, and glgB, involved in starch and sucrose metabolism. The transcription factors MYB, ERF, bHLH, zinc finger, and MADS-box may regulate these genes involved in hormone signal transduction and starch and sucrose metabolism, which are critical for regulating the transition from endo- to ecodormancy in the buds of AMM. To sum up, these results provide insights into the novel regulatory mechanism of the transition of endo- to ecodormancy in underground buds of AMM, and offer new analytical strategies for breaking dormancy in advance and shortening breeding time.