Autumn leaf senescence and coloration is a complex process and a striking natural phenomenon. Here, through biology approach integrating transcriptomic analyses in Ginkgo biloba, we determined that the content of chlorophyll decreased during leaf senescence, while carotenoid components increased until late October in the turning stage (TS) and then decreased in the yellow leaf stage (YS). Simultaneously, chlorophyll biosynthesis genes exhibited significantly lower expression levels while chlorophyll degradation genes showed increased expression from the green leaf stage (GS) to YS. However, carotenoid biosynthesis-related genes showed enhanced expression, especially in TS. An analysis of the expression of genes related to senescence demonstrated that the expression levels of most abscisic acid- and jasmonic acid-related genes, autophagy, WRKY, and NAC genes increased, whereas cytoskeleton-, photosynthesis-, and antioxidation-related genes decreased from GS to YS. Furthermore, G. biloba seedlings exogenously treated with abscisic acid, jasmonic acid, or ultraviolet-B radiation all showed obvious color variation and senescence symptoms. We used these exogenously seedlings to further validate the function of several genes involved in chlorophyll biosynthesis and senescence. Taken together, these results contribute to the elucidation of the molecular mechanisms of leaf coloration and senescence in G. biloba as well as in the identification of candidate genes involved in this process.

The pollen intine plays important roles in pollen germination and tube growth, but related information in Ginkgo biloba remains unclear. We isolated and obtained de-exined pollen from G. biloba. Using fluorescent probes, we observed the strongest cellulose fluorescence in the pollen intine. De-esterified pectin immunolabeled with JIM5 was present throughout the entire cell wall, whereas esterified pectin recognized by the monoclonal antibody JIM7 was concentrated in some regions. Callose staining with aniline blue was observed across the entire surface of the pollen intine. These results were confirmed by Fourier Transform InfraRed (FTIR) analysis. We also used proteomic approaches to identify different proteins between mature and de-exined pollen (48 h after hydration) in vitro. Based on mass spectrometry, de-exined pollen had more proteins than mature pollen, including calmodulin, serine hydroxymethyltransferase, β-galactosidase 6, and class Ⅳ chitinase. According to Gene Ontology (GO) analysis, the differentially expressed proteins were mainly associated with transportation, defense reaction, sugar metabolism, energy metabolism, signal transduction, and cell wall formation. These findings suggest that most proteins involved in pollen germination and pollen tube growth are synthesized during pollen hydration, indicating the important role of pollen hydration in the reproductive process of G. Biloba.