Heavy ion beams and gamma rays induce biological changes and flavonoid accumulation in Astragalus mongholicus Bunge

•Compared with gamma rays irradiation, heavy ion beams had stronger inhibitory effects on the growth of Astragalus mongholicus Bunge seedlings, while having less effects on antioxidase and physiological response.•The suitable doses of heavy ion beams and gamma rays irradiations for Astragalus mongholicus Bunge seeds were 200–250 Gy and 400 Gy, respectively.•50 Gy heavy ion beams and 100 Gy gamma rays irradiations could significantly stimulate the accumulation of flavonoids in Astragalus mongholicus Bunge. Astragalus mongholicus Bunge (A. mongholicus) is a perennial herb in the Fabaceae family. Its dried rhizome has been used in clinical practice in China for more than 2000 years. However, the limited germplasm resources and unstable quality of A. mongholicus have limited its large-scale cultivation and wide application. Therefore, there is an urgent need to breed stable varieties. At present, heavy ion beams (HIBs) and gamma rays are important mutagenesis tools applied in medicinal plants. The aim of this investigation was to assess the effects of various doses (0, 50, 100, 200, and 400 Gy) of HIBs and gamma rays on the development, physiological reaction, and secondary metabolite accumulation of A. mongholicus. The findings indicated that the LD50 of the A. mongholicus seeds to HIBs and gamma rays was 200–250 Gy and 400 Gy, respectively. As the radiation dose increased, there was a subsequent increase in the inhibition of seedling height, plant diameter, and number of branches and leaves, as well as a decrease in the chlorophyll a, b, and carotenoid contents of leaves. Additionally, the chlorophyll fluorescence parameter NPQ and flavonoid contents (total flavonoids, Calycosin-7-glucoside, Calycosin, Ononin, and Methylnissolin-3-O-glucoside) were also affected, which resulted in a distinct decrease in Y(II) values and diverse levels of elevation in leaf MDA content, SOD, and POD activities. Differently, CAT activity was substantially reduced, except for 50 Gy HIBs irradiation. Overall, upon the same dose of the two radiation qualities, HIBs had a stronger inhibitory effect on the growth of Astragalus seedlings, but less effect on antioxidant enzymes and physiological responses. There was no difference between two radiation qualities in increasing trend of flavonoid composition. The present study showed that HIBs is more beneficial for A. membranaceus mutation breeding research and would be promising tool for A. mongholicus mutation breeding.