Li‐Min Lu

How organs partition themselves into discrete domains with distinct functions is a fundamental question in biology. The gynoecium of flowering plants provides an excellent system to address this question. Here, we show that the boundary between the stigma and style at the gynoecium apex is established by the complementary distribution of the phytohormone auxin and the Auxin Response Factor (ARF), ETTIN (ETT). Mechanistically, auxin induces ETT protein destabilization via the ubiquitin–proteasome pathway. A short sequence motif within an intrinsically disordered region is required for this auxin-triggered degradation. Disruption of this motif leads to ectopic ETT accumulation at the gynoecium apex and consequently abolishes stigma-style boundary development. We further demonstrate that this previously unrecognized mode of auxin-induced ARF instability is evolutionarily conserved among ETT orthologs across angiosperms. In summary, this study reveals how graded auxin distribution affects ARF transcription factor activity, contributing to the establishment of the stigma-style boundary, ensuring correct gynoecium formation and reproductive success in flowering plants.

Medicinal plants used by ethnic groups are shaped by environmental constraints (local flora), vertical inheritance (ancestor‐descendant inheritance within an ethnic group), and horizontal transmission (cultural exchange between ethnic groups). Understanding these drivers is critical for deciphering traditional ethnic medicinal plant practices and human‐mediated plant dispersals. Here, we integrated a high‐resolution phylogeny of 5,194 medicinal angiosperms with ethnobotanical data from 36 Chinese ethnic groups. The results reveal that medicinal plant selection shows weak evolutionary constraints, and the inclusion of exotic species—those native to other regions of China but absent from a given ethnic group's area—does not alter the fundamental clustering patterns of ethnic medicinal floras. We identify a profound biogeographic divergence: Ethnic medicinal floras are split into distinct northwestern and southeastern clades, with the Hengduan Mountains region serving as a decisive natural barrier. While environmental factors drive this primary regional division, we also observe progressive convergence in medicinal plant use through horizontal transmission across both clades. This ongoing cultural homogenization poses a significant threat to the preservation of unique, localized ethnobotanical knowledge. Together, our findings provide a comprehensive framework for how environmental barriers and cultural exchange interact to shape the biogeographic structure of traditional medicine.

Fruits are a key feature defining angiosperms, yet how local growth is coordinated during development to generate diverse fruits remains unclear. Here, we demonstrate that the Capsella rubella C2H2-zinc finger transcription factor JAGGED (CrJAG) controls fruit shape determination by promoting both cell division and anisotropic growth. At the molecular level, CrJAG physically interacts with members of the Capsella rubella MULTICOPY SUPPRESSOR OF IRA1 (CrMSI) histone chaperone family, increasing the chromatin accessibility and thereby sustaining the expression of genes involved in fruit morphogenesis. The resulting closed chromatin state in Crjag fruits is characterized by a reduction of the active histone marker (H3K18ac) and an increase of the repressive marker (H3K27me3). Further expression and pharmacological treatment analyses indicate that the developmental defects in Crjag fruits are largely attributable to down-regulation of the key cell-cycle regulator CrAUR2. Collectively, our findings therefore suggest that fine-tuning the cell cycle via epigenetic modification represents an additional, essential layer of regulation critical to organ development and diversification.

Understanding plant adaptation is critical under intensifying global aridification. Succulence, a key drought-resistance innovation, has evolved repeatedly across plant lineages, yet its intrinsic genomic drivers remain underexplored. Integrating comprehensive evidence from genomics, ecology, and morphology, we investigate adaptation to aridity in the tree grape genus, Cyphostemma (Vitaceae), whose species span environmental gradients from rainforests to deserts and exhibit wide genomic and phenotypic variation. Utilising genome assemblies of representative Cyphostemma species, we demonstrate that specific long terminal repeat retrotransposon (LTR-RT) lineages thrived through the radiation of Cyphostemma and led to substantial intron expansion, a phenomenon rarely studied in eudicots. The intronic LTR-RT insertions likely enhanced tolerance of genome structural changes, facilitating succulence evolution. Genomes of succulents were further expanded by intergenic LTR-RTs, which exhibit recurrent evolutionary advantages in arid and seasonal habitats. Our study reveals how genomic landscapes are shaped by both intrinsic LTR-RT dynamics and extrinsic environmental forces. Critically, we suggest that stochastic dynamics of LTR-RT communities enhance genomic evolvability, enabling adaptive evolution in plants.

Identifying centres of neo- and palaeo-endemism is crucial for defining global conservation priorities, yet data gaps hinder prioritization in megadiverse regions. Using a dated phylogeny of 16,585 native vascular plant species, we unravel spatio-temporal dynamics of China’s extant flora. Temporally, most genera originated in the Oligocene–Miocene, whereas the Pleistocene was key for speciation, tying floristic assembly to Pleistocene climatic oscillations. Spatially, mismatched phylogenetic and taxonomic endemism centres highlight complementary conservation priorities. We identify three major taxonomic endemism centres across China, with Central China, embedded within the East Asian subtropical evergreen broad-leaved forest ecoregion, emerging as a critical and overlooked conservation gap. This region harbours over 14,431 vascular plant species, including at least 2,024 endemics, but has experienced severe loss of its original natural vegetation. We therefore advocate its designation as a global biodiversity hotspot. Our multi-dimensional assessment challenges frameworks that neglect evolutionary history and underscores the global conservation importance of Central China.

Fruits that protect the seeds and aid their dispersal are a key feature distinguishing angiosperms from other land plants, and fruit shape varies widely between species. However, it remains largely unknown how local growth behaviors are coordinated during development to generate fruits with characteristic sizes and shapes. Members of the Capsella genus in the mustard family produce unique fruits with an evolutionarily derived heart shape, making it an exceptional system suited for addressing this question. In this study, we demonstrate that the Capsella rubella C2H2-zinc finger transcription factor JAGGED (CrJAG) controls fruit shape. Whole-mount live imaging analysis indicates that CrJAG regulates valve development by promoting both cell division and anisotropic growth. Ectopic expansion of the valve epidermal cells in Crjag mutants is accompanied by mis-patterned endoreduplication events. CrJAG physically interacts with the histone chaperones Capsella rubella MULTICOPY SUPPRESSOR OF IRA1 members, increasing the chromatin accessibility and thereby sustaining the expression of genes involved in fruit morphogenesis. The resulting closed chromatin state in Crjag fruits is characterized by a reduction of the active histone marker (H3K18ac) and an increase of the repressive marker (H3K27me3). Expression analyses and pharmacological treatments indicate that the developmental defects in Crjag fruits are largely attributable to down-regulation of the key cell-cycle regulator CrAUR2 . Collectively, our findings suggest that fine-tuning the cell cycle via epigenetic modification represents an additional, essential layer of regulation critical to organ development.

Genome size, the total amount of DNA content in the cell nucleus, varies greatly among flowering plants. One factor underlying this variation is the environment under which plants evolve. Given this premise, harsh environmental conditions in arid regions may profoundly influence genome evolution. However, the specific impact of aridification on genome size evolution, particularly for African lineages, remains largely unexplored. Here, we investigate linkages between genome size evolution and ecological adaptation using the genus Cyphostemma in the grape family (Vitaceae) as a model. Cyphostemma species exhibit genome size expansion and remarkable morphological traits in arid environments, including succulent stems or leaves and loss of tendrils. Our biogeographic reconstruction, based on substantial taxon sampling (112 of 200 species), reveals that Cyphostemma originated in continental Africa during the late Eocene to Oligocene and has undergone rapid radiation since the middle Miocene, coinciding with intensified aridification and geological activity in eastern Africa. Incorporating extensive data on traits, habitats, genome size, and chromosome numbers, we show that Cyphostemma species with the largest genomes are succulent polyploids restricted to nutrient‐rich limestone outcrops. Broad‐scale analyses across eudicots further confirm that larger genomes are significantly associated with both succulence and arid habitats. Our findings reveal a strong association between genome size expansion, polyploidy, and adaptive traits, indicating that genome size is a hitherto neglected trait associated with the radiation of succulent plants during the African aridification in the Cenozoic.