The genome of the flying spider-monkey tree fern, Alsophila spinulosa, is reported in Nature Plants this week, providing new insights into tree fern biology. Despite ferns' high ornamental value and potential as a source of natural products with pharmaceutical applications, little is known about their evolution, with only two small genomes published from the heterosporous Salviniales. In the study, a team led by Chinese Academy of Sciences researchers generated a chromosomal-scale genome assembly of A. spinulosa, which they characterized in detail including DNA methylation, repeat landscape, and the history of whole-genome duplications. They also carried out genome-powered investigations into the plant's vascular tissues and metabolic diversity and used genome resequencing data to reconstruct its demographic history. Key findings include the identification of a phenolic compound in the plant's xylem and the molecular basis for its biosynthesis, as well as two genetic bottlenecks that resulted in rapid demographic declines of A. spinulosa. The genome, the scientists write, "provides a unique reference for inferring the history of genetic diversity, secondary metabolite biosynthesis, and evolution of tree ferns for better protection and application of tree ferns in the future."
Applying single-nucleus RNA sequencing (snRNA-seq) to Purkinje cells, the sole output neurons of the cerebellar cortex, a group led by Washington University School of Medicine scientists has uncovered a subpopulation of these cells that is involved in learning. Due to the architecture and relatively low number of Purkinje neurons, single-cell transcriptomic profiling of these cells has been a challenge. In their study, which appears in this week's Nature, the researchers isolated green fluorescent protein tagged-nuclei in different cerebellum cell types, followed by snRNA-seq. They identify two major subpopulations of Purkinje neurons that bear distinct transcriptomic features and find that one of these subpopulations exhibits robust plasticity of gene expression in mice subjected to sensorimotor and learning experience. In vivo experimentation showed that this subpopulation of Purkinje cells plays a crucial role in associative learning. "Our findings define how diversification of Purkinje neurons is linked to their responses in motor learning and provide a foundation for understanding their differential vulnerability to neurological disorders," the authors conclude.