The sunflower family (Asteraceae) is the largest and the most diverse flowering plant family, comprising 24 000-30 000 species and 1600-1700 genera. In China, Asteraceae are also the largest family, with approximately 2336 indigenous species in 248 genera. In the past two decades, molecular phylogenetic analyses has contributed greatly to our understanding of the systematics of Asteraceae. Nevertheless, the large-scale analyses and knowledge about the relationships of Chinese Asteraceae at the generic level as a whole are far from complete due to difficulties in sampling. In this study, we presented a three-marker (rbcL, ndhF, and matK) phylogeny of Asteraceae, including 506 genera (i.e., approximately one-third of Asteraceae genera). The study sampled 200 Chinese genera (i.e., approximately 80% of Chinese Asteraceae genera). The backbones of the new phylogeny were largely congruent with earlier studies, with 13 subfamilies and 45 tribes recognized. Chinese Asteraceae were distributed in 7 subfamilies (Mutisioideae, Wunderlichioideae, Carduoideae, Pertyoideae, Gymnarrhenoideae, Cichorioideae, and Asteroideae) and 22 tribes (Mutiseae, Hyalideae, Cardueae, Pertyeae, Gymnarrheneae, Vernonieae, Cichorieae, Doroniceae, Senecioneae, Astereae, Anthemideae, Gnaphalieae, Calenduleae, Inuleae, Athroismeae, Helenieae, Coreopsideae, Neurolaeneae, Tageteae, Millieae, Eupatorieae, and Heliantheae). Chinese Asteraceae lacked 6 basal subfamilies and 23 tribes. Several previously ambiguous relationships were clarified. Our analyses also resolved some unplaced genera within Chinese Asteraceae. Finally, our phylogenetic tree was used to revise the classification for all genera of Chinese Asteraceae. In total, 255 genera, 22 tribes, and 7 subfamilies in China are recognized.

Belowground plant traits play important roles in plant diversity loss driven by atmospheric nitrogen (N) deposition. However, the way N enrichment shapes plant microhabitats by patterning belowground traits and finally determines aboveground responses is poorly understood. Here, we investigated the rhizosheath trait of 74 plant species in seven N-addition simulation experiments across multiple grassland ecosystems in China. We found that rhizosheath formation differed among plant functional groups and contributed to changes in plant community composition induced by N enrichment. Compared with forb species, grass and sedge species exhibited distinct rhizosheaths; moreover, grasses and sedges expanded their rhizosheaths with increasing N-addition rate which allowed them to colonize belowground habitats. Grasses also shaped a different microenvironment around their roots compared with forbs by affecting the physicochemical, biological, and stress-avoiding properties of their rhizosphere soil. Rhizosheaths act as a "biofilm-like shield" by the accumulation of protective compounds, carboxylic anions and polysaccharides, determined by both plants and microorganisms. This enhanced the tolerance of grasses and sedges to stresses induced by N enrichment. Conversely, forbs lacked the protective rhizosheaths which renders their roots sensitive to stresses induced by N enrichment, thus contributing to their disappearance under N-enriched conditions. This study uncovers the processes by which belowground facilitation and trait matching affect aboveground responses under conditions of N enrichment, which advances our

SUMMARY Coumarins are natural products with important medicinal values, and include simple coumarins, furanocoumarins and pyranocoumarins. Female ginseng (Angelica sinensis) is a renowned herb with abundant coumarins, originated in China and known for the treatment of female ailments for thousands of years. The molecular basis of simple coumarin biosynthesis in A. sinensis and the evolutionary history of the genes involved in furanocoumarin biosynthesis are largely unknown. Here, we generated the first chromosome‐scale genome of A. sinensis. It has a genome size of 2.37 Gb, which was generated by combining PacBio and Hi‐C sequencing technologies. The genome was predicted to contain 43 202 protein‐coding genes dispersed mainly on 11 pseudochromosomes. We not only provided evidence for whole‐genome duplication (WGD) specifically occurring in the Apioideae subfamily, but also demonstrated the vital role of tandem duplication for phenylpropanoid biosynthesis in A. sinensis. Combined analyses of transcriptomic and metabolomic data revealed key genes and candidate transcription factors regulating simple coumarin biosynthesis. Furthermore, phylogenomic synteny network analyses suggested prenyltransferase genes involved in furanocoumarin biosynthesis evolved independently in the Moraceae, Fabaceae, Rutaceae and Apiaceae after ζ and ε WGD. Our work sheds light on coumarin biosynthesis, and provides a benchmark for accelerating genetic research and molecular breeding in A. sinensis.

Butylphthalide, one type of phthalides, is one of the first-line drugs for ischemic stroke therapy, while no enzyme involved in its biosynthesis pathway has been reported. Here, we present the first haplotype-resolved genome of Ligusticum chuanxiong Hort., a long-cultivated and phthalide-rich medicinal plant in Apiaceae. Based on comprehensive candidate gene screening, four Fe (II)- and 2-oxoglutarate-dependent dioxygenases (2OGDs) and two CYPs were mined and further biochemically verified as phthalide C-4/C-5 desaturase (P4,5Ds) that converts senkyunolide A to l-n- butylphthalide (l-NBP) and ligustilide to butylidenephthalide. The substrate promiscuity and functional redundancy featured for P4,5Ds may contribute to the high phthalide diversity in L. chuanxiong. Notably, comparative genomic evidence supported L. chuanxiong as a diploid hybrid with L. sinense as a potential parent. The two haplotypes demonstrated exceptional structure variance and diverged around 3.42 million years ago (Ma). Our study is an icebreaker for the dissection of phthalide biosynthesis pathway and reveals the hybrid origin of L. chuanxiong. These findings will facilitate the future metabolic engineering for l-NBP production and breeding efforts for L. chuanxiong.

Based on evidence from specimens and fieldwork, Aster zayuensis Y. L. Chen is shown to be conspecific with Duhaldea eupatorioides (DC.) Steetz.

Stipa shanxiensis, a cryptic species within Stipa grandis that originated from central and western China, is described based on morphological, genomic, and ecological data from field and common garden experiments. Stipa shanxiensis morphologically resembles S. grandis, although phylogenetically it is closely related to the less morphologically similar Stipa baicalensis and Stipa krylovii. Of the eight significant morphological differences between S. shanxiensis and S. grandis, the two, cauline ligules longer than 2 cm with a filiform apex, and hairs shorter than 0.2 mm on the adaxial surface of the cauline uppermost leaves can be used to distinguish the species. Results from a common garden experiment verified that the two diagnostic characteristics were relatively stable and less morphologically plastic in response to environmental variation. Furthermore, a significant ecological divergence was found between S. shanxiensis and S. grandis, such that the former preferred warmer and more humid climates, and their predicted distribution was generally separated. Taken together, our results highlight that the integrative taxonomic approach was valuable for recognizing a new cryptic species in Stipa. In particular, we find that common garden experiments involving the effects of growth stage and characteristic position helped to morphologically diagnose cryptic species. These findings may also facilitate our understandings of ecological adaption and phenotypic plasticity in response to environmental change.

Homosporous lycophytes (Lycopodiaceae) are a deeply diverged lineage in the plant tree of life, having split from heterosporous lycophytes (Selaginella and Isoetes) ~400 million years ago (MYA). Compared to the heterosporous lineage, Lycopodiaceae has markedly larger genome sizes and remains the last major plant clade for which no genomic data has been available. Here, we present chromosomal genome assemblies for two homosporous lycophyte species, the allotetraploid Huperzia asiatica and the diploid Diphasiastrum complanatum. Remarkably, despite that the two species diverged ~350 MYA, around 30% of the genes are still in syntenic blocks. Furthermore, both genomes had undergone independent whole genome duplications and the resulting intra-genomic syntenies have likewise been preserved relatively well. Such slow genome evolution over deep time is in stark contrast to heterosporous lycophytes and is correlated with a decelerated rate of nucleotide substitution. Together, the genomes of H. asiatica and D. complanatum not only fill a crucial gap in the plant genomic landscape, but also uncover a possibly unique genomic contrast between homosporous and heterosporous species.

Abstract—A new species of Artemisia (Asteraceae: Antemideae) from Xizang, China, A. baxoiensis, is described, illustrated, and discussed based on morphological, micromorphological, and molecular phylogenetic evidence. It grows in the Nu Jiang dry-hot valley and is narrowly distributed. This plant is similar to Neopallasia pectinata, but different in capitula and indumentum. Artemisia baxoiensis has a distinctive morphology with a pectinately pinnatisect leaf blade and unusually dense glandular hairs.