Cytological, Physiological and Genotyping-by-Sequencing Analysis Revealing Dynamic Variation of Leaf Color in Ginkgo biloba L.

Ginkgo biloba has unique leaf color and high ornamental value. Here, we conducted seasonal dynamic analyses of leaf color, morphology, physiology, and biochemistry in the new variety Huangjinwanliang (HJWL), using the golden-leaf ginkgo Xiajin (XJ) as a control, and performed genotyping-by-sequencing (GBS) to explore genetic differences. The results showed that both varieties were golden-yellow leaves in spring and autumn, transitioning to green in summer. The total chlorophyll and carotenoid contents in HJWL (1.45~4.84 mg/g and 0.09~0.39 mg/g) were significantly higher than those in XJ (1.42~3.93 mg/g and 0.08~0.34 mg/g). HJWL exhibited a higher number of chloroplasts, with visible single lamellar thylakoids, whereas XJ had fewer chloroplasts. Chloroplast fluorescence and photosynthetic parameters indicated that HJWL possesses a greater capacity for light acclimatization. The total flavonoids and wax content of HJWL (16.67 ± 0.33 mg/g and 18.22 ± 0.15 mg/g) were significantly higher than those of XJ (14.15 ± 0.31 mg/g and 30.19 ± 0.18 mg/g). GBS analysis revealed distinct genome-wide molecular bases between HJWL and XJ. These findings demonstrate that HJWL’s leaf color and extended ornamental period make it a valuable landscape tree species for spring and autumn, suitable for promotion as an ornamental tree.