Salicylic acid-induced flavonoid accumulation in Ginkgo biloba leaves is dependent on red and far-red light

Flavonoids play important roles in plant immune responses, but the molecular mechanism and influencing factors on flavonoid accumulation during Ginkgo immune responses are largely unknown. In this research, post-harvest Ginkgo leaves cultured in the dark were treated with salicylic acid (SA). A transcriptome analysis and total flavonoid measurement showed decreased flavonoid biosynthesis and accumulation in leaves. Experiments carried out in seedlings, young and adult trees, showed increased flavonoid content under light conditions but decreased content under dark conditions after treatment with SA. A detailed analysis of individual flavonoids showed similar changes for most of their contents, although some showed different change trends. Single-colored light experiments revealed that red and far-red light, but not blue light, were required in SA-induced flavonoid accumulation. The results clarified the importance of light in SA-induced flavonoid accumulation and provided valuable information to the Ginkgo related pharmaceutical industry.