Single-cell transcriptome atlas reveals spatiotemporal developmental trajectories in the basal roots of moso bamboo (Phyllostachys edulis)

Roots are essential for plant growth and development.Bamboo is a large Poaceae perennial with 1642 species worldwide.However,little is known about the transcriptional atlas that underpins root cell-type differentiation.Here,we set up a modified protocol for protoplast preparation and report single-cell transcriptomes of 14279 filtered single cells derived from the basal root tips of moso bamboo.We identified four cell types and defined new cell-type-specific marker genes for the basal root.We reconstructed the developmental trajectories of the root cap,epidermis,and ground tissues and elucidated critical factors regulating cell fate determination.According to in situ hybridization and pseudotime trajectory analysis,the root cap and epidermis originated from a common initial cell lineage,revealing the particularity of bamboo basal root development.We further identified key regulatory factors for the differentiation of these cells and indicated divergent root developmental pathways between moso bamboo and rice.Additionally,PheWOX13a and PheWOX13b ectopically expressed in Arabidopsis inhibited primary root and lateral root growth and regulated the growth and development of the root cap,which was different from WOX13 orthologs in Arabidopsis.Taken together,our results offer an important resource for investigating the mechanism of root cell differentiation and root system architecture in perennial woody species of Bambusoideae.

Chromosomal-level genome and metabolome analyses of highly heterozygous allohexaploid Dendrocalamus brandisii elucidate shoot quality and developmental characteristics

Dendrocalamus brandisii(Munro)Kurz is a sympodial bamboo species with inimitable taste and flavorful shoots.Its rapid growth and use as high-quality material make this bamboo species highly valued for both food processing and wood applications.However,genome information for D.brandisii is lacking,primarily due to its polyploidy and large genome size.Here,we assembled a high-quality genome for hexaploid D.brandisii,which comprises 70chromosomes with a total size of 2,756 Mb,using long-read Hi Fi sequencing.Furthermore,we accurately separated the genome into its three constituent subgenomes.We used Oxford Nanopore Technologies long reads to construct a transcriptomic dataset covering 15 tissues for gene annotation to complement our genome assembly,revealing differential gene expression and post-transcriptional regulation.By integrating metabolome analysis,we unveiled that well-balanced lignin formation,as well as abundant flavonoid and fructose contents,contribute to the superior quality of D.brandisii shoots.Integrating genomic,transcriptomic,and metabolomic datasets provided a solid foundation for enhancing bamboo shoot quality and developing efficient gene-editing techniques.This study should facilitate research on D.brandisii and enhance its use as a food source and wood material by providing crucial genomic resources.