Royal Botanic Gardens, Kew, is a non-departmental public body in the United Kingdom sponsored by the Department for Environment, Food and Rural Affairs. An internationally important botanical research and education institution, it employs 1,100 staff. Its board of trustees is chaired by Dame Amelia Fawcett. The organisation manages botanic gardens at Kew in Richmond upon Thames in southwest London, and at Wakehurst, a National Trust property in Sussex which is home to the internationally important Millennium Seed Bank, whose scientists work with partner organisations in more than 95 countries. Kew, jointly with the Forestry Commission, founded Bedgebury National Pinetum in Kent in 1923, specialising in growing conifers. In 1994 the Castle Howard Arboretum Trust, which runs the Yorkshire Arboretum, was formed as a partnership between Kew and the Castle Howard Estate.In 2018 the organisation had 1,858,513 public visitors at Kew, and 354,957 at Wakehurst. Its 326-acre (132 ha) site at Kew has 40 historically important buildings; it became a UNESCO World Heritage Site on 3 July 2003. The collections at Kew and Wakehurst include over 27,000 taxa of living plants, 8.3 million plant and fungal herbarium specimens, and over 40,000 species in the seed bank.
The seed is an essential stage in the life history of gymnospermous and angiospermous plants, facilitating both their survival and dispersal. We reappraise knowledge of the evolutionary history of the gymnospermous seed, from its origin in the late Devonian through to the well-known end-Permian extinctions - an interval encompassing the origins of most major lineages of seed-bearing plants. The framework for our broader discussions is a novel cladistic analysis of anatomically preserved Palaeozoic seeds, analysing 79 seed-species for 89 morphological characters in a matrix containing only 24% missing values. The resulting consensus tree is weakly but fully resolved and compatible with traditional division into three informal seed groups: paraphyletic lagenocarps, paraphyletic trigonocarps and monophyletic cardiocarps. Three seed-genera - Rhychosperma, Albertlongia and Muricosperma - are revealed as potential 'missing links' between groups, and modest re-circumscription of seed-genera is required. Although the value of single-organ phylogenies remains controversial, the present seed-tree topology receives general support from the dated sequence of first appearances of seed-species in the fossil record, and from the topologies of morphological cladistic studies that combined conceptually reconstructed fossil plants with primitive extant lineages, notably ginkgos and cycads. Branch lengths in the tree and phenetic distances in ordinations of the matrix indicate similar overall rates of character change through the Palaeozoic, rather than a fractal pattern reflecting progressively increasing constraint, although early changes in architectural and pollination-related characters gradually give way to greater experimentation with the internal layering and external topography of the testa. Our process-based evolutionary inferences are informed by extant gymnosperms, particularly Cycas and Ginkgo. The origin of the true seed is attributed primarily to (1) the complex biochemical signalling needed to allow the sperm to reach the archegonia through the megasporangium wall and (2) the localised apoptosis of the megasporangium hypothesised to have simultaneously allowed hollowing out of the nucellar apex to form a sophisticated pollen-receiving apparatus (the pollen chamber) and secretion of a pollination drop to capture air-borne (pre)pollen. Subsequent potential key innovations include transfer of function of both pollination-drop channelling and pollen chamber sealing from the nucellar salpinx to the integumentary micropyle, and introduction of a haustorial pollen tube to direct spermatozoa towards the archegonia. Assuming that the seed-plant megasporangium terminates an axis, synorganisation has played a key role in seed evolution, leaf-like lateral organs being repeatedly pulled towards the apex and incorporated into the terminal structure. Lateral webbing of integumentary lobes eventually almost fully enclosed the nucellus, while a similar synorganisation process affecting a lower set of vegetative organs formed a cupule as yet another protective layer surrounding one or more ovules. Our tree refutes viewing these evolutionary developmental trends as linear transition series. The earliest seeds were small but soon increased to reach the maximum size achievable by gymnosperms. Dehiscence and dormancy mechanisms were likely primitive at best, while increasingly complex layering and sculpting of the testa may have aided both abiotic and biotic dispersal. The end-Permian extinction of plants bearing lagenocarps and trigonocarps is attributed tentatively to one or more of several features of reproductive biology identified as being vulnerable to desiccation.
Exploring genetic variation and screening for disease resistance is an important step in crop breeding initiatives but is lacking for many bean varieties, including mung bean. A study was conducted to evaluate morpho-agronomic traits and screen mung bean genotypes for resistance to powdery mildew disease. A total of 132 mung bean and one rice bean (C3) (as check) genotypes were evaluated in an augmented incomplete block design across two cropping seasons. Diversity was evaluated across 40 morpho-agronomic traits, comprising 13 quantitative traits. Qualitative traits were summarized using pivot tables, while variation in quantitative traits was investigated using linear models, principal component analysis (PCA), and agglomerative hierarchical clustering (AHC). The genotypes displayed wide variation for the majority of the traits evaluated, and significant differences were observed among the genotypes, block effects, and seasons. Similarly, the effects due to genotypes, checks and genotypes and checks were significant. One mung bean (G32) genotype and one rice bean (R200) genotype presented resistance to powdery mildew under field conditions. Among the quantitative traits evaluated, only days to maturity and shelling percentage showed statistically significant negative correlations with disease severity. PCA revealed that the first four PCs explained 60.64
BACKGROUND AND AIMS:Hybridization and introgression play crucial roles in evolution and adaptation. Although the influence of ploidy differences on interspecific hybridization has been documented, most studies have focused on single pairs of hybridizing species, thereby limiting our understanding of broader patterns of interspecific gene flow. Here, we investigate hybridization among six partially sympatric Betula species to examine patterns of genetic admixture involving diploid, tetraploid and octoploid species occupying diverse microhabitats. METHODS:We sampled 148 populations across China, representing three diploid species (B. ashburneri and B. costata from section Costatae, and B. platyphylla from section Betula), two tetraploid species (B. ermanii and B. utilis from section Costatae) and one octoploid species (B. dahurica from section Dahuricae), and genotyped 2610 individuals at 15 microsatellite loci. We assessed population structure and compared levels of genetic admixture among the six Betula species using pairwise analyses. KEY RESULTS:Genetic diversity increased with ploidy level and was positively correlated with latitude. Analyses of population genetic structure revealed genetic admixture among Betula species with different ploidy levels. The proportion of hybrids among species within section Costatae was significantly higher than that among sections, although it was not significantly associated with phylogenetic distances between species. CONCLUSIONS:Higher genetic diversity in northern populations of the six Betula species suggests the existence of glacial refugia at higher latitude. The comprehensive dataset for six Betula species not only enables investigation of patterns of genetic admixture across ploidy levels but also fosters novel hypotheses regarding the origins of polyploid lineages and the factors influencing the dynamics of interspecific hybridization.
Genome size is a fundamental biological characteristic, yet its evolutionary dynamics remain insufficiently understood, partly because few plant groups offer the cytogenetic and phylogenomic data required for genus-level analyses. In this study, we estimated genome size (2C values) for 80 species (c, 75% of the genus), covering all infrageneric categories (three subgenera, ten sections). Genome-size evolution was examined within a newly generated, time-calibrated phylogenetic framework based on the Angiosperms353 target-capture probe set including 89% of the species in the genus, and integrated with updated karyotype descriptors including chromosome numbers, total haploid karyotype length (THL), interchromosomal coefficient of variation in chromosome length (CVCL), and intrachromosomal mean centromeric asymmetry (MCA). Genome size varied 6.5-fold across the genus, ranging from 1.65 to 10.60 pg (i.e., from very small to intermediate genomes). Phylogenetically informed regressions revealed a strong positive relationship between 2C values and THL, indicating that changes in nuclear DNA content are accommodated by proportional modifications in chromosome size. In contrast, genome size showed no significant association with chromosome number or karyotype asymmetry, suggesting that genome-size diversification has occurred largely independently of major chromosomal rearrangements. Chromosome-number reconstructions confirmed a highly conserved karyotype across the genus, with only a single abrupt shift and a small number of minor dysploid changes. Ancestral-state reconstruction and comparative evolutionary modelling revealed that genome-size diversification is strongly shaped by phylogenetic structure and characterised by repeated reductions from an intermediate ancestral genome. Overall, Helianthemum provides a powerful model for understanding how genome size evolves within a conserved chromosomal framework.
Documented living plant collections distinguish botanic gardens from other green spaces and horticultural landscapes. With more than 3,500 collections worldwide, these institutions steward at least 105,634 species-around 30% of all land plant diversity-while fulfilling amenity, educational, scientific and conservation roles. However, twenty-first-century challenges demand a re-evaluation of how these collections are documented and managed. We argue that meeting these emerging needs requires higher standards of coordinated information management and innovation in data infrastructures across the global network. This Perspective critically examines data management practices of living collections supporting scientific research and conservation, from institutional to global levels. We identify the renewed demands on living collections, highlight exemplar global data infrastructures, define data challenges inherent to living collections and explore how current systems fall short in enabling a connected global system. Finally, we outline a vision for high-performance collections, fully integrated into a robust global data ecosystem.
