Transcriptome and biochemical response to 60Co gamma radiation exposure on the grafted seedlings of Paeonia suffruticosa

Tree peony is considered as an important ornamental and medicinal plant in China, and Co-60 gamma radiation breeding can be potentially used to improve its quality. In this study, we have analyzed the biochemical characteristics and transcriptomic effects induced by different doses of Co-60 gamma radiation on the grafted seedlings to explore the possible mutagenic effects of Co-60 gamma radiation on the tree peony. The higher radiation doses were found to be harmful to the seedlings, and LD50 (50% of the lethal value) was 40.30 Gy. Co-60 gamma radiation treatment obviously affected the physiological and biochemical states of tree peony. The activity of antioxidant enzymes including superoxide dismutase, peroxidase, and catalase gradually increased after radiation exposure, with maximal at 40 Gy. The total soluble protein content gradually decreased, while the content of proline and malondialdehyde was significantly increased. A total of 77,699 unigenes were identified, of which 399, 1447 and 1928 identified were differentially expressed genes (DEGs) in H0 (control) vs H1 (10 Gy), H0 vs H5 (50 Gy), H1 vs H5, respectively. GO and KEGG results showed that the DEGs were closely related to phenylalanine metabolism, lipid metabolism, carbohydrate metabolism pathways, plant hormone signal transduction and secondary biosynthesis metabolism. A total of 768 different expressed transcription factors were identified, which were mainly distributed in MYB, WRKY, NAC and other families related to plant stress regulation which was up-regulated upon exposure to 50 Gy. This is the first transcriptome-based study to demonstrate significant variations in the expression of the various genes in response to Co-60 gamma radiation. The findings of this study could be useful in the development of a mutation breeding program for tree peony.

Automated summary

This study analyzed the biochemical characteristics and transcriptomic effects induced by different doses of Co-60 gamma radiation on tree peony seedlings. The higher radiation doses were found to be harmful to the seedlings. The study identified differentially expressed genes related to various metabolic pathways and stress regulation factors that respond to radiation exposure.