Comparative Transcriptomic Analysis Reveals the Regulatory Mechanism of Terpene Trilactones Improvement by Exogenous Methyl Jasmonate in Ginkgo biloba

Terpene trilactones (TTLs) are one of the main active ingredients of Ginkgo biloba. Owing to TTL’s unique chemical structure, it is difficult to increase TTL content through chemical and biological methods. Studying its regulatory mechanism is important in the G. biloba industry. The effect of exogenous methyl jasmonate (MeJA) on the physiological and molecular mechanism of TTL biosynthesis was studied. These results showed that MeJA treatment could improve the TTL contents, soluble sugar, starch, soluble protein, endogenous hormones (ZT, GA3, IAA, and ABA), antioxidant enzymes (catalase, peroxidase, and superoxide dismutase), and the efficiency of photosynthesis in G. biloba leaves. A total of 100 differentially expressed genes (DEGs) were identified between the control group and MeJA treatment through RNA-seq analysis. The results indicated that exogenous MeJA treatment upregulated the expression levels of the following genes: BMY (beta-amylase) in the starch and sucrose metabolic pathway; PEX7 (peroxin-7) in the peroxisome pathway; psbA (photosystem II reaction center D1 protein), psbC (photosystem II CP43 chlorophyll apoprotein), psaA (photosystem I P700 chlorophyll a apoprotein A1), and petF (photosynthetic electron transport ferredoxin) in the photosynthesis pathway; and CYP450 (Gb-16765) (cytochromeP450). Exogenous MeJA treatment can promote physiological indexes (photosynthetic efficiency, starch, sucrose, antioxidant enzyme activities, etc.) and then regulating differential genes, thus controlling the synthesis of TTLs.