Genome Assembly and Winged fruit Gene Regulation of Chinese Wingnut: Insights from Genomic and Transcriptomic Analyses

The genomic basis and biology of winged fruit are interesting issues in ecological and evolutionary biology. Chinese wingnut (Pterocarya stenoptera) is an important garden and economic tree species in China. The genomic resources of this hardwood tree could provide advanced genomic studies of Juglandaceae and their evolutionary relationships. Here, we reported a high-quality reference genome of P. stenoptera (N50 = 35.15 Mb) and provided a comparative analysis of Juglandaceae genomes. Paralogous relationships among the 16 chromosomes of the Chinese wingnut genome revealed eight main duplications representing the subgenome. Molecular dating suggested that the most recent common ancestor of P. stenopetera and Cyclocarya paliurus diverged from Juglans around 56.7 million years ago (Mya). The expanded and contracted gene families were associated with cutin, suberine, and wax biosynthesis, cytochrome P450, and anthocyanin biosynthesis. We identified large inversion blocks between the P. stenoptera genome and its relatives, which are enriched in genes related lipid biosynthesis and metabolism, and starch and sucrose metabolism. The twenty-eight individuals were clearly clustered into three groups responding to three species, namely Pterocarya macroptera, Pterocarya hupehensis, and P. stenoptera, based on whole genome resequencing data. Morphological and gene expression analysis showed that CAD, COMT, LOX, and MADS-box play important roles during the five developmental stages of wingnuts. Our study highlights the evolutionary history of the P. stenoptera genome and supports P. stenoptera as an appropriate Juglandaceae model for studying winged fruits. These results provide a theoretical basis for the evolution, development, and diversity of woody plant winged fruits.