Objective To explore the function of short-chain dehydrogenases/reductases (SDRs) in safflower flavonoid, especially hydroxysafflower yellow A (HSYA) biosynthesis. Methods SDRs involved in HSYA biosynthesis pathway were screened based on safflower transcriptome database and metabolome database. The expression pattern was analyzed by qRT-PCR. The overexpression vector was constructed by seamless cloning technology, then genetically transformed to the Yunnan Weishan safflower strain by Agrobacterium gv3101. The transgenic T₂ generation plants were positively verified, and the gene expression of corolla SDRs was analyzed. The content of secondary metabolites was assayed by UPLC-Q-TOF/MS. Results Three SDRs genes named CtSDR1, CtSDR2 and CtSDR3 involved in HSYA biosynthesis pathway were screened. Their expression in safflower from high to low was corolla > leaf > stem > root. The expression level in corolla increased gradually with corolla development. qRT-PCR analysis of corolla with positive verification of genome insertion sequence showed that the transcription level of CtSDR3 in corolla of T₂ positive plants increased by 2~3 times compared with the blank control group, and the content of secondary metabolite HSYA increased by 7.1%~16.6% (P< 0.05). Conclusion CtSDR3 may be involved in the biosynthesis of flavonoids, especially HSYA, in safflower. It provides the support data for explaining the function of CtSDR3 in HSYA biosynthesis pathway.

Objective To provide valuable insights for improving China’s special drug approval system by conducting an in-depth analysis of the practices of the U.S. Food and Drug Administration （FDA） in granting Emergency Use Authorizations （EUAs） for drugs. Methods A retrospective analysis was conducted on the FDA’s EUA decision-making process for COVID-19 therapeutics between January 2020 and June 2023. Results During the COVID-19 pandemic, the FDA adopted a series of regulatory science approaches to facilitate rapid approval of COVID-19 therapeutic drugs. The FDA granted EUA for a total of 15 COVID-19 therapeutic drugs and 4 COVID-19 vaccines, including expanded indications for marketed drugs, EUA for investigational drugs, revocation of EUA, and marketing after EUA. The main mechods for the rapid approval of EUA drugs by the FDA included the use of existing clinical trial data, omission of animal efficacy testing, merging of phase 1 and phase 2 clinical trials, and the use of clinical outcomes as surrogate endpoints, among other regulatory science methods. Conclusion The practices of the FDA in Emergency Use Authorization (EUA) of drugs, particularly its incorporation of regulatory scientific methods into the EUA process and the establishment of proactive monitoring mechanisms for drugs granted EUA, are worthy of emulation by China. It is suggested that China consider the experience of the FDA in the EUA system for drugs to further optimize and improve its special approval system for drugs.