Functional Identification of 9-Cis-Epoxycarotenoid Dioxygenase Genes in Double Dormant Plant-Herbaceous Peony

Abstract Seed dormancy and germination is a complex process, which is affected by external environmental conditions and internal factors independently or mutually. Phytohormones play an important regulatory role in this process. ABA was the main phytohormone affecting herbaceous peony seed dormancy release. However, the mechanism of ABA in the dormancy release of herbaceous peony needs to be further explored. Here, transcriptome data was screened from the perspective of ABA metabolism, and significantly differentially expressed PlNCED1 and PlNCED2 were obtained. We found that their expression trends were positively correlated with ABA content. Among them, PlNCED2 had a stronger regulatory effect on ABA content and was more sensitive to exogenous ABA. Overexpression and silencing of PlNCEDs in callus could affect the expression of PlCYP707As and the content of endogenous ABA. Through the observation of seed germination of Arabidopsis thaliana (A. thaliana), we found PlNCED1 and PlNCED2 promoted seed dormancy, and the promotion effect of PlNCED2 was more obvious. In general, PlNCED1 and PlNCED2 participated in the dormancy release of herbaceous peony seeds by regulating the accumulation of endogenous ABA. Our work can reveal the molecular mechanism and related theories of ABA involved in herbaceous peony seed dormancy release.