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Ginger (Zingiber officinale Roscoe) is an important vegetable with medicinal value. Rhizome development determines ginger yield and quality. However, little information is available about the molecular features underlying rhizome expansion and maturation. In this study, we investigated anatomy characteristics, lignin accumulation and transcriptome profiles during rhizome development. In young rhizomes, the vascular bundle (VB) was generated with only vessels in it, whereas in matured rhizomes, three to five layers of fibre bundle in the xylem were formed, resulting in VB enlargement. It indicates VB development favouring rhizome swelling. With rhizome matured, the lignin content was remarkably elevated, thus facilitating tissue lignification. To explore the regulators for rhizome development, nine libraries including ginger young rhizomes (GYR), growing rhizomes (GGR), and matured rhizomes (GMR) were established for RNA-Seq, a total of 1264 transcription factors (TFs) were identified. Among them, 35, 116, and 14 differentially expressed TFs were obtained between GYR and GGR, GYR and GMR, and GGR and GMR, respectively. These TFs were further divided into three categories. Among them, three ZobHLHs (homologs of Arabidopsis LHW and AtbHLH096) as well as one DIVARICATA homolog in ginger might play crucial roles in controlling VB development. Four ZoWRKYs and two ZoNACs might be potential regulators associated with rhizome maturation. Three ZoAP2/ERFs and one ZoARF might participate in rhizome development via hormone signalling. This result provides a molecular basis for rhizome expansion and maturation in ginger.

The WD40 transcription factor family is a superfamily found in eukaryotes and implicated in regulating growth and development. In this study, 167 WD40 family genes are identified in the Ginkgo biloba genome. They are divided into 5 clusters and 16 subfamilies based on the difference analysis of a phylogenetic tree and domain structures. The distribution of WD40 genes in chromosomes, gene structures, and motifs is analyzed. Promoter analysis shows that five GbWD40 gene promoters contain the MYB binding site participating in the regulation of flavonoid metabolism, suggesting that these five genes may participate in the regulation of flavonoid synthesis in G. biloba. The correlation analysis is carried out based on FPKM value of WD40 gene and flavonoid content in 8 tissues of G. biloba. Six GbWD40 genes that may participate in flavonoid metabolism are screened. The biological functions of the WD40 family genes in G. biloba are systematically analyzed, providing a foundation for further elucidating their regulatory mechanisms. A number of WD40 candidate genes involved in the biosynthesis and metabolism of G. biloba also predicted. This study presents an important basis and direction for conducting further research on the regulatory network of flavonoid synthesis and metabolism.

As a common mutation trait in plants, leaf colour mutation is related to the degree of chlorophyll and anthocyanin changes and the destruction of chloroplast structure. This study summarizes the latest research progress in leaf colour mutation mechanism, including the metabolic basis of plant leaf colour mutation, leaf colour mutation caused by gene mutation in the chlorophyll metabolism pathway, leaf colour mutation caused by blocked chloroplast development, leaf colour mutation controlled by key transcription factors and non-coding RNAs, leaf colour mutation caused by environmental factors, and leaf colour mutation due to the involvement of the mevalonate pathway. These results will lay a theoretical foundation for leaf colour development, leaf colour improvement, and molecular breeding for leaf colour among tree species.