Treatment of with Exogenous Sodium Selenite Affects Its Physiological Growth, Changes Its Phytohormones, and Synthesizes Its Terpene Lactones.

Ginkgolide is a unique terpenoid natural compound in , and it has an important medicinal value. Proper selenium has been reported to promote plant growth and development, and improve plant quality, stress resistance, and disease resistance. In order to study the effects of exogenous selenium (Se) on the physiological growth and the content of terpene triolactones (TTLs) in seedlings, the seedlings in this work were treated with NaSeO. Then, the physiological indexes, the content of the TTLs, and the expression of the related genes were determined. The results showed that a low dose of NaSeO was beneficial to plant photosynthesis as it promoted the growth of ginkgo seedlings and increased the root to shoot ratio. Foliar Se application significantly increased the content of soluble sugar and protein and promoted the content of TTLs in ginkgo leaves; indeed, it reached the maximum value of 7.95 mg/g in the ninth week, whereas the application of Se to the roots inhibited the synthesis of TTLs. Transcriptome analysis showed that foliar Se application promoted the expression levels of , , , and genes, whereas its application to the roots promoted the expression of and genes. The combined analysis results of metabolome and transcriptome showed that genes such as , , , , and were significantly positively correlated with transcription factors (TFs) and /, and they were also positively correlated with the contents of terpene lactones (ginkgolide A, ginkgolide B, ginkgolide M, and bilobalide). Endogenous hormones (MeJA-ILE, ETH, and GA7) were also involved in this process. The results suggested that NaSeO treatment affected the transcription factors related to the regulation of endogenous hormones in , and further regulated the expression of genes related to the terpene synthesis structure, thus promoting the synthesis of ginkgo TTLs.