Integrated physiological characterisation and transcriptomics reveals drought tolerance differences between two cultivars of A. sinensis at seedling stage.

Background: Drought can adversely affect the growth and development of Angelica sinensis (Oliv.) Diels seedlings. M1 and M2 are two cultivars of A. sinensis with distinct phenotypic traits, and they may exhibit different stress resistances. This study compares the growth, physiological characteristics, and transcriptome data of two cultivars of A. sinensis seedlings to explore their differences in drought tolerance and the underlying molecular mechanisms.

Methods And Results: We treated seedlings of M1 and M2 using the natural drought method in pots and compared their growth, physiological characteristics, and transcriptomic data. Under drought stress, M2 showed less phenotypic changes and higher RWC of leaves, photosynthetic parameters, and antioxidant enzyme activities. By analyzing RNA-seq data, 13,941 and 9913 DEGs were identified from M1 and M2. These DEGs are enriched in important pathways related to plant responses to drought stress, including photosynthesis (LHC, HEMA, PAO), antioxidant defense (APX, GPX, EBF1/2), and secondary metabolites (PAL, 4CL, CAD). A thorough analysis of the significant DEGs between the two cultivars of A. sinensis revealed that the expression levels of these DEGs were generally consistent with the physiological changes observed under drought stress. In addition, key transcription factors such as WRKY6, PAT1, and SCL13 were screened through WGCNA.

Conclusions: M2 seedlings showed greater drought tolerance compared to M1. The research results not only provide insights into the molecular mechanisms of A. sinensis in response to drought stress, but also offer a reference for the evaluation of A. sinensis germplasm resources and the selection and breeding of drought-tolerant cultivars.