Ilia Leitch

Royal Botanic Gardens, Kew · Trait Diversity and Function

Sapindales is an angiosperm order of high economic and ecological value comprising nine families, c. 479 genera, and c. 6570 species. However, family and subfamily relationships in Sapindales remain unclear, making reconstruction of the order’s spatio-temporal and morphological evolution difficult. In this study, we used Angiosperms353 target captu...

Giant genomes are rare across the plant kingdom and their study has focused almostexclusively on angiosperms and gymnosperms. The scarce genetic data that are available for ferns,however, indicate differences in their genome organization and a lower dynamism compared toother plant groups. Tmesipteris is a small genus of mainly epiphytic ferns that...

Asteraceae, the daisy family, are one of the most diverse families of angiosperms and are predominant in many ecosystems, including grasslands, deserts, savannas and high-elevation mountains. They are characterized by a peculiar inflorescence, the capitulum, which mimics a flower, but is actually made up of many tightly grouped florets. The capitul...

Background and aims Among the numerous pantropical species of the yam genus, Dioscorea, only a small group occurs in the Mediterranean basin, including two narrow Pyrenean endemics (Borderea clade), and two Mediterranean-wide species (D. communis and D. orientalis, Tamus clade). However, several currently unrecognized species and infraspecific taxa...

(1) Evolution of genome size is shaped by various intrinsic and extrinsic factors. We explored three long-standing hypotheses concerning factors shaping the global distribution of genome size: the mutational hazard hypothesis, the polyploidy-mediated hypothesis and the climate-mediated hypothesis. (2) We compiled the largest genome size dataset to...

We present genome assemblies from four Malus domestica cultivars (the apple; Streptophyta; Magnoliopsida; Rosales; Rosaceae). The genome sequences are 643–653 megabases in span. The greater part of each assembly length (99.24–99.74%) is scaffolded into 17 chromosomal pseudomolecules. The mitochondrial and plastid genomes were also assembled and are...

Background and aims. Among the numerous pantropical species of the yam genus, Dioscorea , only a small group occurs in the Mediterranean basin, including two narrow Pyrenean endemics (Borderea clade), and two Mediterranean-wide species ( D. communis and D. orientalis , Tamus clade). However, several currently unrecognized species and infraspecific...

The Andean fever tree (Cinchona L.; Rubiaceae) is a source of bioactive quinine alkaloids used to treat malaria. C. pubescens Vahl is a valuable cash crop within its native range in northwestern South America, however, genomic resources are lacking. Here we provide the first highly contiguous and annotated nuclear and plastid genome assemblies usin...

Protecting nature’s contributions to people requires accelerating extinction risk assessment and better integrating evolutionary, functional and used diversity with conservation planning. Here, we report machine learning extinction risk predictions for 1,381 palm species (Arecaceae), a plant family of high socio-economic and ecological importance....

Flow cytometry (FCM) is currently the most widely‐used method to establish nuclear DNA content in plants. Since simple, 1‐3‐parameter, flow cytometers, which are sufficient for most plant applications, are commercially available at a reasonable price, the number of laboratories equipped with these instruments, and consequently new FCM users, has gr...

Simple telomeric repeats composed of 6‐7 iterating nucleotide units are important sequences typically found at the ends of chromosomes. Here we analyzed their abundance and homogeneity in 42 gymnosperm (29 newly sequenced), 29 angiosperm (1 newly sequenced) and 8 bryophytes using bioinformatics, conventional cytogenetic and molecular biology approa...

Ecotypes are distinct populations within a species that are adapted to specific environmental conditions. Understanding how these ecotypes become established, and how they interact when reunited, is fundamental to elucidating how ecological adaptations are maintained. This study focuses on Themeda triandra, a dominant grassland species across Asia,...

Grassland ecosystems cover ~40% of global land area and contain ~40% of soil organic carbon. Understanding the effects of adding nutrients to grasslands is essential because they provide much of our food, support diverse ecosystem services and harbor rich biodiversity. ● Using the meadow steppe (grassland) study site of Inner Mongolia, we manipulat...

A new study uncovers a novel trade-off in polyploid plants. While the larger cells of polyploids benefit from increased cell storage and water retention, this comes at the cost of reduced structural stability, potentially impacting survival.

With c. 24 700 species (10% of all flowering plants), Asteraceae are one of the largest and most phenotypically diverse angiosperm families, with considerable economic and ecological importance. Asteraceae are distributed worldwide, from nearly polar latitudes all the way to the tropics, and occur across a diverse range of habitats from extreme des...

Cytological data resources are crucial to the study and understanding of the evolution of complex taxa. Recent research on the genus Begonia L. has provided a robust phylogenetic background for the analysis of evolutionary patterns across the group and has established that Begonia is variable in genome size and chromosome number. This paper provide...

Reliably documenting plant diversity is necessary to protect and sustainably benefit from it. At the heart of this documentation lie species concepts and the practical methods used to delimit taxa. Here, we apply a total-evidence, iterative methodology to delimit and document species in the South American genus Victoria (Nymphaeaceae). The systemat...

Genome size varies 2,400‐fold across plants, influencing their evolution through changes in cell size and cell division rates which impact plants’ environmental stress tolerance. Repetitive element expansion explains much genome size diversity, and the processes structuring repeat ‘communities’ are analogous to those structuring ecological communit...

Increased ecological disturbances, species invasions, and climate change are creating severe conservation problems for several plant species that are widespread and foundational. Understanding the genetic diversity of these species and how it relates to adaptation to these stressors are necessary for guiding conservation and restoration efforts. Th...

Polyploidy is a widespread phenomenon across angiosperms, and one of the main drivers of diversification. Whilst it frequently involves hybridisation, autopolyploidy is also an important feature of plant evolution. Minority cytotypes are frequently overlooked due to their lower frequency in populations, but the development of techniques such as flo...

Climate change is expected to disproportionately affect sub‐Saharan Africa in the next century, posing a threat to the livelihoods of smallholder farmers and deepening food insecurity. To adapt to this threat, more climate‐resilient crops need to be brought into the food system; these may be developed through breeding with crop wild relatives with...

Background The Andean fever tree ( Cinchona L.; Rubiaceae) is the iconic source of bioactive quinine alkaloids which have been key to treating malaria for centuries. In particular, C. pubescens Vahl has been an important source of income for several countries in its native range in north-western South America. However, the genomic resources require...

Gnetophytes are an enigmatic gymnosperm lineage comprising three genera, Gnetum, Welwitschia and Ephedra, which are morphologically distinct from all other seed plants. Their distinctiveness has triggered much debate as to their origin, evolution and phylogenetic placement among seed plants. To increase our understanding of the evolution of gnetoph...

The vascular flora of Britain and Ireland is among the most extensively studied in the world, but the current knowledge base is fragmentary, with taxonomic, ecological and genetic information scattered across different resources. Here we present the first comprehensive data repository of native and alien species optimized for fast and easy online a...

Genome size varies 2,400-fold across plants, influencing their evolution through changes in cell size and cell division rates which impact plants’ environmental stress tolerance. Repetitive element expansion explains much genome size diversity, and the processes structuring repeat ‘communities’ are analogous to those structuring ecological communit...

[This corrects the article DOI: 10.3389/fgene.2021.726211.].

Plant genomes are highly diverse in size and repetitive DNA composition. In the absence of polyploidy, the dynamics of repetitive elements, which make up the bulk of the genome in many species, are the main drivers underpinning changes in genome size and the overall evolution of the genomic landscape. The advent of high-throughput sequencing techno...

Background and aims: Genome size varies considerably across the diversity of plant life. Although genome size is, by definition, affected by genetic presence/absence variants, which are ubiquitous in population sequencing studies, genome size is often treated as an intrinsic property of a species. Here, we studied intra- and interspecific genome s...

Background and Aims The dynamics of genome evolution caused by whole genome duplications and other processes are hypothesized to shape the diversification of plants and thus contribute to the astonishing variation in species richness among the main lineages of land plants. Ferns, the second most species rich lineages of land plants are highly suita...

The gymnosperm Welwitschia mirabilis belongs to the ancient, enigmatic gnetophyte lineage. It is a unique desert plant with extreme longevity and two ever-elongating leaves. We present a chromosome-level assembly of its genome (6.8 Gb/1 C) together with methylome and transcriptome data to explore its astonishing biology. We also present a refined,...

Premise: The inference of evolutionary relationships in the species-rich family Orchidaceae has hitherto relied heavily on plastid DNA sequences and limited taxon sampling. Previous studies have provided a robust plastid phylogenetic framework, which was used to classify orchids and investigate the drivers of orchid diversification. However, the e...

Angiosperms show a remarkable range in genome size (GS), yet most species have small genomes, despite the frequency of polyploidy and repeat amplification in the ancestries of most lineages. It has been suggested that larger genomes incur costs that have driven selection for GS reduction, although the nature of these costs and how they might impact...

The date palm (Phoenix dactylifera L.) is an iconic crop of hot and arid regions of North Africa, the Middle East and up to northwestern India. It is a member of the genus Phoenix that constitutes a monophyletic group within the Coryphoideae subfamily, in the palm family. The genus Phoenix is composed of around 14 species whose native distribution...

The date palm, Phoenix dactylifera, has been a cornerstone of Middle Eastern and North African agriculture for millennia. It was first domesticated in the Persian Gulf, and its evolution appears to have been influenced by gene flow from two wild relatives, P. theophrasti, currently restricted to Crete and Turkey, and P. sylvestris, widespread from...

PREMISE: Phylogenetic studies in the Compositae are challenging due to the sheer size of the family and the challenges they pose for molecular tools, ranging from the genomic impact of polyploid events to their very conserved plastid genomes. The search for better molecular tools for phylogenetic studies led to the development of the family-specifi...

Genome size (GS) displays a broad variation across land plants. Although it is considered to be influenced by selection pressures depending on different environmental conditions and life-history strategies, the underlying drivers of GS variation across lineages remain elusive. Latitude gradients of GS tend to show contrasting patterns among differe...

An analysis of over 10,000 plant genome sizes (GS) indicate that most species have smaller genomes than expected given the incidence of polyploidy in their ancestries, suggesting selection for genome downsizing. However, comparing ancestral GS with the incidence of ancestral polyploidy suggests that the rate of DNA loss following polyploidy is like...

The tree of life is the fundamental biological roadmap for navigating the evolution and properties of life on Earth, and yet remains largely unknown. Even angiosperms (flowering plants) are fraught with data gaps, despite their critical role in sustaining terrestrial life. Today, high-throughput sequencing promises to significantly deepen our under...

Genome size (GS) is a key trait related to morphology, life history, and evolvability. Although GS is, by definition, affected by presence/absence variants (PAVs), which are ubiquitous in population sequencing studies, GS is often treated as an intrinsic property of a species. Here, we studied intra- and interspecific GS variation in taxonomically...

Gap analysis of the available genomic data (i.e. identifying taxonomic groups with no representative genome assemblies) is a fundamental first step to design effective sampling strategies for whole genome sequencing (WGS) initiatives. We identified the significant holes that remain in genomic resources of the Ascomycota e the largest fungal phylum...

While polyploidy (whole genome multiplication) is generally considered rare in extant gymnosperms (with the exception of Ephedra, Ephedraceae), the occurrence of sporadic polyploid individuals belonging to various genera in the conifer family Cupressaceae has been reported in the literature. In addition, recent studies have revealed that polyploidy...

Geographical isolation facilitates the emergence of distinct phenotypes within a single species, but reproductive barriers or selection is needed to maintain the polymorphism after secondary contact. Here, we explore the processes that maintain intraspecific variation of C4 photosynthesis, a complex trait that results from the combined action of mu...

The tree of life is the fundamental biological roadmap for navigating the evolution and properties of life on Earth, and yet remains largely unknown. Even angiosperms (flowering plants) are fraught with data gaps, despite their critical role in sustaining terrestrial life. Today, high-throughput sequencing promises to significantly deepen our under...

Background and aims: Extant plant groups with a long fossil history are key elements in understanding vascular plant evolution. Horsetails (Equisetum, Equisetaceae) have a nearly continuous fossil record dating back to the Carboniferous, but their phylogenetic and biogeographic patterns are still poorly understood. We use here the most extensive p...

Enabling food security requires access to a broad range of genetic resources to facilitate crop breeding. This need is increased in a climate change scenario, which will require the production of novel crops adapted to new conditions. However, many major crops have reduced genetic diversity due to the genetic bottlenecks that they have experienced...

Repeated sequences and polyploidy play a central role in plant genome dynamics. Here, we analyze the evolutionary dynamics of repeats in tetraploid and hexaploid Spartina species that diverged during the last 10 million years within the Chloridoideae, one of the poorest investigated grass lineages. From high-throughput genome sequencing, we annotat...

Over the years, the amount of DNA in a nucleus (genome size) has been estimated using a variety of methods, but increasingly, flow cytometry (FCM) has become the method of choice. The popularity of this technique lies in the ease of sample preparation and in the large number of particles (i.e., nuclei) that can be analyzed in a very short period of...

Insights into genome size dynamics and its evolutionary impact remain limited by the lack of data for many plant groups. One of these is the genus Iris, of which only 53 out of c. 260 species have available genome sizes. In this study, we estimated the C-values for 41 species and subspecies of Iris mainly from the Eastern Mediterranean region. We c...

The date palm ( Phoenix dactylifera ) has been a cornerstone of Middle Eastern and North African agriculture for millennia. It is presumed that date palms were first domesticated in the Persian Gulf and subsequently introduced into North Africa, where their evolution in the latter region appears to have been influenced by gene flow from the wild re...

Premise of the study Evolutionary relationships in the species-rich Orchidaceae have historically relied on organellar DNA sequences and limited taxon sampling. Previous studies provided a robust plastid-maternal phylogenetic framework, from which multiple hypotheses on the drivers of orchid diversification have been derived. However, the extent to...

C4 photosynthesis evolved multiple times independently in angiosperms, but most origins are relatively old so that the early events linked to photo- synthetic diversification are blurred. The grass Alloteropsis semialata is an exception, as this species encompasses C4 and non-C4 populations. Using phylogenomics and population genomics, we infer the...

Asexual reproduction has often been regarded as an evolutionary dead end, but asexual lineages (most notably those that are apomictic) are present in several angiosperm families and often comprise a large number of taxa, both widespread and endemic. Investigating correlations between genetic, environmental and taxonomic factors and the incidence of...

Given the 2,400-fold range of genome sizes (0.06-148.9 Gbp (gigabase pair)) of seed plants (angiosperms and gymno-sperms) with a broadly similar gene content (amounting to approximately 0.03 Gbp), the repeat-sequence content of the genome might be expected to increase with genome size, resulting in the largest genomes consisting almost entirely of...

Kew’s State of the World’s Plants and Fungi project provides assessments of our current knowledge of the diversity of plants and fungi on Earth, the global threats that they face, and the policies to safeguard them. Produced in conjunction with an international scientific symposium, Kew’s State of the World’s Plants and Fungi sets an important inte...

Main conclusion Cytogenomic characterization of Erythrostemon hughesii reveals a heterogeneity of repeats in its subtelomeric heterochromatin. Comparative analyses with other Caesalpinia group species reveal a significant reduction in the abundance of Ty3-gypsy/Chromovirus Tekay retrotransposons during its evolution. In numerically stable karyotype...

For millennia, humans have used plants and fungi, as foods, fuels, fibers, and medicines; and have developed techniques for improving their usefulness to our species, mostly through selection of desirable traits. With human populations forecast to rise, the availability of arable land likely to fall amid climate change and increasing urbanization,...

Asexual reproduction has often been regarded as an evolutionary dead end, but asexual lineages (most notably those that are apomictic) are present in several angiosperm families and often comprise a large number of taxa, both widespread and endemic. Investigating correlations between genetic, environmental and taxonomic factors and the incidence of...

A therapeutic solution to the coronavirus disease 2019 (COVID-19) pandemic is urgently needed, but new drug discovery and development are lengthy processes. Pharmaceuticals derived from plants and fungi remain important in our armory against numerous diseases (1, 2), yet much of plant and fungal biodiversity remains unexplored for drug discovery (3...

Now published in the book The date palm genome, Vol. 1 (Springer): https://link.springer.com/chapter/10.1007/978-3-030-73746-7_2 The date palm (Phoenix dactylifera L.) is the iconic crop of hot and arid regions of North Africa, the Middle East and up to northwestern India. It is a member of the genus Phoenix, that constitutes a monophyletic group...

C 4 photosynthesis evolved multiple times independently in angiosperms, but most origins are relatively old so that the early events linked to photosynthetic diversification are blurred. The grass Alloteropsis semialata is an exception, as this single species encompasses C 4 and non-C 4 populations. Using phylogenomics and population genomics, we i...