Recently, a research team from Yijishan Hospital of Anhui Medical University, in collaboration with the Wuhan Botanical Garden of the Chinese Academy of Sciences and other institutions, published a study titled "Haplotype-resolved genome assembly of Bletilla striata (Thunb.) Reichb.f. to elucidate medicinal values" in the internationally renowned plant science journal The Plant Journal. This study decodes the first high-quality haplotype genome of an orchid species, providing new insights into the evolution of orchids. Through multi-omics research and experiments, the study also reveals the mechanism of polysaccharide biosynthesis in Bletilla striata.

Bletilla striata is a rare and valuable medicinal herb in China, rich in compounds such as polysaccharides, flavonoids, terpenoids, and sterols, which have significant economic, medicinal, and ornamental value. The research team employed HIFI and Hi-C-assisted assembly technologies to obtain the first high-level haplotype genome of an orchid species: Haplotype-A (2.37 Gb with a scaffold N50 of 146.39 Mb and a Contig N50 of 1.65 Mb) and Haplotype-B (2.43 Gb with a scaffold N50 of 150.22 Mb and a Contig N50 of 1.66 Mb). The evidence suggests that Bletilla striata underwent two rounds of whole-genome duplication (WGD): one is the ancient WGD event shared by most monocots, and the other is a more recent WGD event unique to orchids. This study also reconstructs the ancestral karyotypes of 18 ancient orchid chromosomes and the evolutionary trajectories of 16 modern chromosomes in Bletilla striata. Comparative genomic analysis indicates that the expansion of gene families in Bletilla striata may play a crucial role in the biosynthesis of secondary metabolites and environmental adaptation. By combining genomic and transcriptomic data, the study identifies ten core members from nine gene families that are likely involved in the biosynthesis of Bletilla striata polysaccharides (BSP).

DOI: https://doi.org/10.1111/tpj.15892