Search

Aims and background The resurrection plant Myrothamnus flabellifolia tolerates complete desiccation and is a great model for studying how plants cope with extreme drought. Root-associated microbes play a major role in stress tolerance and are an attractive target for enhancing drought tolerance in staple crops. However, how these dynamics play out under the most extreme water limitation remains underexplored. This study aimed to identify bacterial and fungal communities that tolerate extreme drought stress in the bulk soil, rhizosphere, and endosphere of M. flabellifolia. Methods High-throughput amplicon sequencing was used to characterise the microbial communities associated with M. flabellifolia. Results The bacterial phyla that were most abundant across all compartments were Acidobacteriota, Actinobacteriota, Chloroflexota, Planctomycetota, and Pseudomonadota, while the most abundant fungal phyla were Ascomycota and Basidiomycota. Although the bulk soil hosted multiple beneficial root-associated microbes, the rhizosphere compartment showed the highest functional diversity of bacteria and fungi. In contrast, the endosphere exhibited a low abundance and diversity of microbes. These findings share consistent with the theory that M. flabellifolia recruits soil microbes from the bulk to the rhizosphere and finally to the endosphere. It is possible that these microbes could promote drought tolerance in associated plant tissues. Conclusion We find that compartments act as the major driver of microbial diversity, but the soil physicochemical factors also influence microbial composition. These results suggest that the root-associated microbiome of M. flabellifolia is highly structured and may aid in plant function.

Aims and Background The resurrection plant Myrothamnus flabellifolia tolerates complete desiccation and is a great model for studying how plants cope with extreme drought. The response to desiccation in M. flabellifolia leaves has been studied extensively, but little is known about how the associated microbiome contributes to desiccation tolerance. Root-associated microbes play a major role in stress tolerance, and are an attractive target for enhancing drought tolerance in staple crops. However, how these dynamics play out under the most extreme water limitation remains underexplored. Methods The high-throughput amplicon metagenomic technique was used to investigated the bacterial and fungal communities in the bulk soil, rhizosphere, and endosphere of the M. flabellifolia. Results The bacterial phyla that were most abundant across all compartments were Acidobacteriota, Actinobacteria, Chloroflexi, Planctomycetes andProteobacteria, while fungal phyla were Ascomycotaand Basidiomycota. Although the bulk soil hosted multiple beneficial root-associated microbes, the rhizosphere compartment showed the highest functional diversity of bacteria and fungi. In contrast, the endosphere exhibited a low abundance and diversity of microbes. These findings suggest that M. flabellifolia recruits soil microbes from bulk to rhizosphere, many of which may confer extreme drought tolerance and promote plant growth. Conclusion The diverse rhizosphere microbiome is filtered to result in a highly selective endosphere microbiome. We find that compartment niches act as the major driver of microbial diversity, but that soil physicochemical factors also influence the microbial composition. These results suggest that the root-associated microbiome of M. flabellifolia is highly structured and may aid in plant function.

The field of plant science has grown dramatically in the past two decades, but global disparities and systemic inequalities persist. Here, we analyzed ~300,000 papers published over the past two decades to quantify disparities across nations, genders, and taxonomy in the plant science literature. Our analyses reveal striking geographical biases—affluent nations dominate the publishing landscape and vast areas of the globe having virtually no footprint in the literature. Authors in Northern America are cited nearly twice as many times as authors based in Sub-Saharan Africa and Latin America, despite publishing in journals with similar impact factors. Gender imbalances are similarly stark and show remarkably little improvement over time. Some of the most affluent nations have extremely male biased publication records, despite supposed improvements in gender equality. In addition, we find that most studies focus on economically important crop and model species and a wealth of biodiversity is under-represented in the literature. Taken together, our analyses reveal a problematic system of publication, with persistent imbalances that poorly captures the global wealth of scientific knowledge and biological diversity. We conclude by highlighting disparities that can be addressed immediately and offer suggestions for long-term solutions to improve equity in the plant sciences.SIGNIFICANCE STATEMENTWe analyzed ~300,000 papers published over the past two decades to quantify global, gender, and taxonomic disparities in plant science. Our analyses reveal striking geographical biases that are correlated with national affluence. Gender imbalances were also evident, with far more papers led by authors with masculine names than authors with feminine names. Lastly, we identified substantial taxonomic sampling gaps. The vast majority of surveyed studies focused on major crop and model species and the remaining biodiversity accounted for only a fraction of publications. Taken together, our analyses represent an important addition to the growing conversation about diversifying and decolonizing science.

Tolerance to prolonged water deficit occurs along a continuum in plants, with dehydration tolerance (DhT) and desiccation tolerance (DT) representing some of the most extreme adaptations to water scarcity. Although DhT and DT presumably vary among individuals of a single species, this variability remains largely unstudied. Here, we characterized expression dynamics throughout a dehydration-rehydration time-course in six diverse genotypes of the dioecious liverwort Marchantia inflexa. We identified classical signatures of stress response in M. inflexa, including major changes in transcripts related to metabolism, expression of LEA and ELIP genes, and evidence of cell wall remodeling. However, we detected very little temporal synchronization of these responses across different genotypes of M. inflexa, which may be related to genotypic variation among samples, constitutive expression of dehydration-associated transcripts, the sequestration of mRNAs in ribonucleoprotein partials prior to drying, or the lower tolerance of M. inflexa relative to most bryophytes studied to date. Our characterization of intraspecific variation in expression dynamics suggests that differences in the timing of transcriptional adjustments contribute to variation among genotypes, and that developmental differences impact the relative tolerance of meristematic and differentiated tissues. This work highlights the complexity and variability of water stress tolerance, and underscores the need for comparative studies that seek to characterize variation in DT and DhT.

Resurrection plants have an extraordinary ability to survive extreme water loss but still revive full metabolic activity when rehydrated. These plants are useful models to understand the complex biology of vegetative desiccation tolerance. Despite extensive studies of resurrection plants, many details underlying the mechanisms of desiccation tolerance remain unexplored. To summarize the progress in resurrection plant research and identify unexplored questions, we conducted a systematic review of 15 model angiosperm resurrection plants. This systematic review provides an overview of publication trends on resurrection plants, the geographical distribution of species and studies, and the methodology used. Using the Preferred Reporting Items for Systematic reviews and Meta–Analyses protocol we surveyed all publications on resurrection plants from 2000 and 2020. This yielded 185 empirical articles that matched our selection criteria. The most investigated plants were Craterostigma plantagineum (17.5%), Haberlea rhodopensis (13.7%), Xerophyta viscosa (reclassified as X. schlechteri) (11.9%), Myrothamnus flabellifolia (8.5%), and Boea hygrometrica (8.1%), with all other species accounting for less than 8% of publications. The majority of studies have been conducted in South Africa, Bulgaria, Germany, and China, but there are contributions from across the globe. Most studies were led by researchers working within the native range of the focal species, but some international and collaborative studies were also identified. The number of annual publications fluctuated, with a large but temporary increase in 2008. Many studies have employed physiological and transcriptomic methodologies to investigate the leaves of resurrection plants, but there was a paucity of studies on roots and only one metagenomic study was recovered. Based on these findings we suggest that future research focuses on resurrection plant roots and microbiome interactions to explore microbial communities associated with these plants, and their role in vegetative desiccation tolerance.

Resilience to abiotic stress is associated with a suite of functional traits related to defense and longevity. Stress tolerant plants are generally slow growing with extended leave lifespans and reduced allocation to reproduction. Resurrection plants are ideal systems to test for trade-offs associated with stress tolerance due to their extreme resiliency. While, growth defense trade-offs are well-characterized, few studies have tested for natural variation associated with tolerating the harshest environments. Here, we surveyed a suite of functional traits related to stress tolerance, leaf economics, and reproductive allocation in natural populations of the South African resurrection plant Myrothamnus flabellifolia. We selected three distinct field sites in South Africa ranging from mesic to xeric. Despite considerable environmental variation across the study area, M. flabellifolia plants were extremely and similarly stress tolerant at all sites. However, we detected notable variation in other life history and morphological traits. Plants in more mesic sites were larger, faster growing, and had more inflorescences. In contrast, plants from the most xeric sites appeared to invest more in persistence and defense, with lower growth rates and less reproductive allocation. Together, this suggests that desiccation tolerance is a binary trait in M. flabellifolia with little natural variation, but that other phenotypes are more labile. The trait syndromes exhibited by plants at the different study sites align with general expectations about growth defense tradeoffs associated with the colonization of extreme environments. We show that plants from the least stressful sites are more reproductive and faster growing, whereas plants from the most stressful sites were slower growing and less reproductive. These findings suggest that M. flabellifolia plants are finely tuned to their environment.

The field of plant genome sequencing has grown rapidly in the past 20 years, leading to increases in the quantity and quality of publicly available genomic resources. The growing wealth of genomic data from an increasingly diverse set of taxa provides unprecedented potential to better understand the genome biology and evolution of land plants. Here we provide a contemporary view of land plant genomics, including analyses on assembly quality, taxonomic distribution of sequenced species and national participation. We show that assembly quality has increased dramatically in recent years, that substantial taxonomic gaps exist and that the field has been dominated by affluent nations in the Global North and China, despite a wide geographic distribution of study species. We identify numerous disconnects between the native range of focal species and the national affiliation of the researchers studying them, which we argue are rooted in colonialism—both past and present. Luckily, falling sequencing costs, widening availability of analytical tools and an increasingly connected scientific community provide key opportunities to improve existing assemblies, fill sampling gaps and empower a more global plant genomics community., Analyses of plant genomes sequenced in the past 20 years, the species taxonomic distribution and national participation reveal that genome quality has increased but substantial taxonomic gaps exist, and that the field has been dominated by the Global North.

The field of plant genomics has grown rapidly in the past 20 years, leading to dramatic increases in both the quantity and quality of publicly available genomic resources. With this ever-expanding wealth of genomic data from an increasingly diverse set of taxa, unprecedented potential exists to better understand the genome biology and evolution of plants. Here, we provide a contemporary view of plant genomics, including analyses on the quality of existing plant genome assemblies, the taxonomic distribution of sequenced species, and how national participation has influenced the field’s development. We show that genome quality has increased dramatically in recent years, that substantial taxonomic gaps exist, and that the field has been dominated by affluent nations in the Global North and China, despite a wide geographic distribution of sequenced species. We identify multiple disconnects between the native range of focal species and the national affiliation of the researchers studying the plants, which we argue are rooted in colonialism--both past and present. However, falling sequencing costs paired with widening availability of analytical tools and an increasingly connected scientific community provide key opportunities to improve existing assemblies, fill sampling gaps, and, most importantly, empower a more global plant genomics community.

Desiccation tolerance has evolved recurrently across diverse land plant lineages as an adaptation for survival in regions where seasonal rainfall drives periodic drying of vegetative tissues. Growing interest in this phenomenon has fueled recent physiological, biochemical, and genomic insights into the mechanistic basis of desiccation tolerance. Although, desiccation tolerance is often viewed as binary and monolithic, substantial variation exists in the phenotype and underlying mechanisms across diverse lineages, heterogeneous populations, and throughout the development of individual plants. Most studies have focused on conserved responses in a subset desiccation-tolerant plants under laboratory conditions. Consequently, the variability and natural diversity of desiccation-tolerant phenotypes remains largely uncharacterized. Here, we discuss the natural variation in desiccation tolerance and argue that leveraging this diversity can improve our mechanistic understanding of desiccation tolerance. We summarize information collected from ~600 desiccation-tolerant land plants and discuss the taxonomic distribution and physiology of desiccation responses. We point out the need to quantify natural diversity of desiccation tolerance on three scales: variation across divergent lineages, intraspecific variation across populations, and variation across tissues and life stages of an individual plant. We conclude that this variability should be accounted for in experimental designs and can be leveraged for deeper insights into the intricacies of desiccation tolerance.

Plant-microbe interactions impact ecosystem function through nutrient cycling, community interactions, and individual costs/benefits to the organisms involved. However, information on the establishment, diversity, and function of plant-microbe interactions remains limited, especially for non-vascular plants. We hypothesized that variation in the environment and sex of a host plant, impact the composition and diversity of associated microbial communities. To test this hypothesis, we characterized the bacteriome of the non-vascular plant, Marchantia inflexa, in both males and females across multiple habitats by targeted sequencing of the bacterial 16S rRNA gene. We describe the bacteriome for M. inflexa, and find that it is abundant and diverse, showing some similarities with other non-vascular plant lineages. Using these data, we detected a habitat specific component of the bacteriome, and sex differences in the bacteriome under common garden conditions. On the basis of known microbial functions, our analyses suggest that the specific taxonomic assemblages of bacteria detected in particular habitat types may serve functional roles; allowing plants to better acclimate to their local environment, and that sex differences in the bacteriome may correspond to subtle differences in the physiology and morphology of the sexes. Our initial characterization of variation in bacteriome composition of this tropical liverwort lineage provides valuable information for better understanding the patterns of plant-microbe interactions across land plants.

We present a draft genome assembly for the tropical liverwort, Marchantia inflexa, which adds to a growing body of genomic resources for bryophytes and provides an important perspective on the evolution and diversification of land plants. We specifically address questions related to sex chromosome evolution, sexual dimorphisms, and the genomic underpinnings of dehydration tolerance. This assembly leveraged the recently published genome of related liverwort, M. polymorpha, to improve scaffolding and annotation, aid in the identification of sex-linked sequences, and quantify patterns of sequence differentiation within Marchantia. We find that genes on sex chromosomes are under greater diversifying selection than autosomal and organellar genes. Interestingly, this is driven primarily by divergence of male-specific genes, while divergence of other sex-linked genes is similar to autosomal genes. Through analysis of sex-specific read coverage, we identify and validate genetic sex markers for M. inflexa, which will enable diagnosis of sex for non-reproductive individuals. To investigate dehydration tolerance, we capitalized on a difference between genetic lines, which allowed us to identify multiple dehydration associated genes two of which were sex-linked, suggesting that dehydration tolerance may be impacted by sex-specific genes.

Water shortage events negatively impact plant productivity, threaten ecosystem functioning, and are predicted to increase dramatically in the coming years. Consequently, building a detailed understanding of how plants respond to water stress is critical for improving predictions of ecological processes and species range shifts under climate change. Here, we characterized patterns of intraspecific variation in dehydration tolerance (DhT, also dehydration tolerant) across a variable landscape in the tropical plant, Marchantia inflexa. DhT enables tissues to survive substantial drying (below an absolute water content of − 10 MPa) and despite the ecological significance of DhT, many questions remain. We tested if DhT was correlated with an environmental exposure gradient, if male and female plants had contrasting DhT phenotypes, and if variation in DhT had a genetic component. To do so, we collected plants from five populations, spanning an environmental exposure gradient in the forests of northern Trinidad, Republic of Trinidad and Tobago. We measured DhT immediately after collection, and after growing plants for ~ 1 year in a common garden. We found that DhT varied significantly among populations and tracked the characterized exposure gradient. Additionally, we showed that phenotypic differences among populations in DhT were maintained in the common garden, suggesting that underlying genetic differences contribute to DhT variability. Finally, we detected a fluctuating sexual dimorphism where males had lower DhT than females in less exposed sites, but not in more exposed sites. Interestingly, this fluctuating sexual dimorphism in DhT was driven primarily by male variation (females exhibited similar DhT across sites).

Background and aims Adaptations allowing plants to cope with drying are particularly relevant in the light of predicted climate change. Dehydration tolerance (DhT, also dehydration-tolerant) is one such adaptation enabling tissue to survive substantial drying. A great deal of work has been conducted on highly DhT species. However, bryophytes showing less intense and variable DhT are understudied, despite the potential for these species to provide an informative link between highly tolerant and sensitive species. In this study, we tested the degree to which DhT varies across populations and the sexes of a species expected to exhibit a moderate DhT phenotype. Methods To test predicted patterns of tolerance we assessed DhT in males and females of Marchantia inflexa from two distinct habitat types that differ in water availability. Both common garden and field-collected tissue was subjected to drying assays at multiple intensities and recovery was monitored by chlorophyll florescence. Verification studies were conducted to confirm the level of dehydration, the rate of drying and the associated changes in photosynthetic physiology. Key results We confirmed our expectation that M. inflexa is able to tolerate moderate dehydration. We also found that females exhibited higher DhT than males, but populations did not differ in DhT when cultured in a common garden. However, field-collected samples exhibited differences in DhT corresponding to environmental dryness, suggesting plasticity in DhT. Conclusions By studying a less extreme DhT phenotype we gained insight into how more sensitive (yet still tolerant) organisms cope with dehydration. Additionally, the identified sex-specific variation in DhT may explain ecological patterns such as female-biased sex ratios. Furthermore, plasticity in DhT has the potential to inform management practices aimed at increasing tolerance to drought conditions.

Beginning some 50 thousand years ago, a technological transition spread across the Near East and into Eurasia, in the most general terms characterized by a shift from preferential, prepared core reduction systems to the serial production of elongated points via opposed platform cores. The earliest known occurrence of such a technological shift is the Emiran Industry, whose oldest manifestations are found in the southern Levant. The cultural and demographic source(s) of this industry, however, remain unresolved. Looking to archaeogenetic research, the emerging picture indicates a major dispersal of our species out of Africa between 100 and 50 thousand years ago. Ancient DNA evidence points to low levels of admixture between Neanderthal and pioneering modern human populations in the Near East. These propositions underscore the significance of the Emiran and beg a reassessment of its origins. In this paper, we ask whether the Emiran was a local development, a cultural/demographic replacement, or the fusion of indigenous and exogenous lithic traditions. Our analysis considers the techno-typological features of the Emiran in relation to late Middle Palaeolithic and contemporaneous assemblages from adjacent territories in northeast Africa and the Arabian Peninsula, in order to identify overlapping cultural features and potential antecedents. Parsi- monious with the archaeogenetic scenario of admixture, the Emiran seems to represent a fusion of local southern Levantine Mousterian tool types with the Afro-Arabian Nubian Levallois reduction strategy. We propose that Emiran technology is primarily rooted in the Early Nubian Complex of the Nile Valley, which spread onto the Arabian Peninsula during the Last Interglacial and developed at the interface of northern Arabia and the southern Levant between 100 and 50 thousand years ago.