Plant Diversity最新文献

Over the past two decades, our understanding of Lauraceae, a large family of woody plants, has undergone significant advances in phylogeny, taxonomy, and biogeography. Molecular systematic studies have elucidated the basic relationships within the family with plastid phylogenomic analyses providing robust support for deep-level relationships between Lauraceae lineages, leading to the recognition of nine tribes: Hypodaphnideae, Cryptocaryeae, Cassytheae, Neocinnamomeae, Caryodaphnopsideae, Mezilaureae, Perseeae, Laureae, and Cinnamomeae, with Mezilaureae validated here. Nuclear genomes and comparative genomics studies have also clarified aspects of the family's evolutionary history and metabolic diversity. Taxonomic studies have focused mainly on the most diverse regions, e.g., tropical Asia, tropical America, and Africa (Madagascar), with six new genera described and five reinstated since the last major overview of the family. The extensive fossil record suggests that Lauraceae diversified globally during the Late Cretaceous and Early Cenozoic. Biogeographic studies indicate that different lineages of the family are sorted into Gondwanan and Laurasian lineages, with patterns resulting from the disruption of boreotropical flora and multiple long-distance dispersal events. Phylogeographic studies, predominantly from East Asia, have shown patterns of in situ survival and demographic stability or expansion during the Quaternary. Nevertheless, many systematic relationships within the family remain unresolved and further research is needed into the complex biogeographic history and ecological roles of Lauraceae. A multifaceted approach integrating genomic studies, field work, morphological and ecological investigations is therefore needed to understand the evolution and diversity of this ecologically and economically significant plant family.

Change of flower color can readily lead to a shift in pollinators, potentially causing pollinator mediated reproductive isolation or even speciation. Here, we examined the ecological and evolutionary consequences of flower color polymorphism in Roscoea cautleoides, an alpine ginger with sympatric distribution of purple- and yellow-flowered plants. Variations in pollinator visitation and specialization to the flower color contributed greatly to pre-zygotic reproductive isolation, with post-zygotic isolation also observed in reciprocal pollination. Yellow-flowered plants evolved independently from purple-flowered plants in two populations due to the absence of anthocyanins, as supported by metabolic, expression, and genetic analysis. Despite early genetic divergence between the two-flower-colored plants, highly differentiated genes were associated with reproduction and stress, while highly selective genes were enriched in stress. Our results suggest that parallel loss of anthocyanins leads to flower color polymorphism in different populations of R. cautleoides, with pollinator preference contributing to reproductive isolation and subsequent genetic differentiation, indicating the process of incipient speciation triggered by flower color changes with sympatric distribution.

The parasitic dodder (Cuscuta, Convolvulaceae) species have wide ranges of hosts. However, some plants, including the cultivated tomato (Solanum lycopersicum), have different degrees of resistance to Cuscuta. The cultivated tomato plants activate a strong hypersensitive response (HR) where Cuscuta haustoria penetrate stems of cultivated tomato, but the underlying mechanisms by which the cultivated tomato perceives Cuscuta and activates resistance remain unclear. In this study, we show that the phytohormones jasmonic acid (JA) and salicylic acid (SA) in cultivated tomato stems were highly induced by Cuscuta australis parasitization. Genetic analyses and experiments of supplementation of JA or SA indicated that the JA and SA pathway not only are both required for activation of HR against Cuscuta parasitization but also function in non-HR-based resistance. The Cuscuta Receptor 1 (CuRe1), which is a leucine-rich repeat receptor-like protein, and suppressor of BAK1-interacting receptor kinase (SOBIR1) and SOBIR1-like, two adaptor kinases, are also important for HR-based and non-HR-based resistance. Importantly, we found that the JA and SA pathway both transcriptionally regulate CuRe1. However, in the cure1 mutants, JA and SA levels were still normally induced by C. australis parasitization. We propose a linear model that an unknown receptor perceives Cuscuta parasitization and thus triggers accumulation of JA and SA, which in turn induce the transcription of CuRe1, and CuRe1 and SOBIR1/SOBIR1-like thereby activate HR-based and non-HR-based resistance to Cuscuta. This study underscores the important roles of hormone signaling and resistance (R) genes in host plant-parasitic plant interactions.

The sugarcane subtribe Saccharinae (Andropogoneae, Poaceae) was established in 1846, but its delimitation has long been debated. Moreover, the relationships among the genera of Saccharinae remain unclear, and there is no consensus on whether Pseudosorghum, a small genus in tropical Asia with only two species, should be included. Here, we performed phylogenomic analyses using whole plastomes (69 of them newly sequenced) from 132 individuals, representing 65 species in 19 related genera. We also built trees with nuclear ribosomal DNA sequences. Our results justify the inclusion of Pseudosorghum, likely also the Eulalia Clade III, in Saccharinae. Furthermore, both morphological and molecular analyses support merging the two Pseudosorghum species. The backbone relationships of the Saccharinae phylogeny were highly supported with four polyphyletic clades of Miscanthus and the inclusion of Narenga and Tripidium rufipilum in Saccharum. Pseudosorghum is moderately supported as sister to the Miscanthus Clade I, while the remaining Tripidium species could be excluded from the subtribe. Saccharinae is estimated to have originated ∼3.73 million years ago in East Asia, followed by intercontinental dispersals. Our study provides a comprehensive phylogenetic framework for future taxonomic revisions of this economically important subtribe.

Pollination niches, which encompass the factors influencing pollen exchange among angiosperms, are fundamental to understanding reproductive success and the intricate eco-evolutionary dynamics of plants. In this study, we investigated pollination niche shift among four sympatric Eriosyce cacti with restricted distributions in the South American Mediterranean region. Utilizing a comprehensive approach-including pollination niche analysis, pollinator color perception studies, reproductive output assessments, molecular phylogenetics, gene flow analyses, and species distribution modeling-we revealed a significant pollination niche displacement in E. chilensis and its variety, E. chilensis var. albidiflora. These taxa transitioned from a hummingbird-pollinated system prevalent in the Eriosyce sect. Neoporteria, characteristic of their sister species E. litoralis, to a bee-pollination strategy akin to that of the co-occurring species E. mutabilis. This shift highlights a simultaneous convergence of E. chilensis toward E. mutabilis and divergence from E. litoralis in pollination strategies, providing adaptive advantages by reducing pollen limitation and enhancing seed production. The morphological and flowering phenological similarities between E. chilensis and E. mutabilis suggest the evolution of a shared advertising display, potentially indicative of floral mimicry, wherein both species benefit from attracting shared bee pollinators. Genomic analyses reveal distinct pollinator-driven selection pressures, with E. chilensis/E. albidiflora exhibiting traits that promote reproductive isolation from E. litoralis, supporting a scenario of rapid speciation occurring within the past half of million years in the absence of geographic barriers. These findings underscore the pivotal role of pollinator interactions in shaping angiosperm speciation and biodiversity, highlighting their dynamic influence on ecological and evolutionary processes.

The primary mechanism driving plant species loss after nitrogen (N) addition has been often hypothesized to be asymmetric competition for light, resulting from increased aboveground biomass. However, it is largely unknown whether plants' access to soil water at different depths would affect their responses, fate, and community composition under nitrogen addition. In a semiarid grassland exposed to 8-years of N addition, we measured plant aboveground biomass and diversity under four nitrogen addition rates (0, 4, 10, and 16 g m^-2 year^-1), and evaluated plant use of water across the soil profile using oxygen isotope. Aboveground biomass increased significantly, but diversity and shallow soil-water content decreased, with increasing rate of nitrogen addition. The water isotopic signature for both plant and soil water at the high N rate indicated that Leymus secalinus (a perennial grass) absorbed 7% more water from the subsurface soil layer (20-100 cm) compared to Elymus dahuricus (a perennial grass) and Artemisia annua (an annual forb). L. secalinus thus had a significantly larger biomass and was more abundant than the other two species at the high N rate but did not differ significantly from the other two species under ambient and the low N rate. Species that could use water from deeper soil layers became dominant when water in the shallow layers was insufficient to meet the demands of increased aboveground plant biomass. Our study highlights the importance of water across soil depths as key driver of plant growth and dominance in grasslands under N addition.

[This corrects the article DOI: 10.1016/j.pld.2024.03.006.].

Predicting whether alien species will invade a native community is a key challenge in invasion ecology. One factor that may help predict invasion success is phylogenetic relatedness. Darwin proposed that closely related species tend to share similar niches, although this relationship may be influenced by various ecological and evolutionary factors. To test this, we classified alien Asteraceae species in China into three categories based on their invasion status and the extent of ecological damage: introduced, naturalized, and invasive. We then compared the genetic relationships and niche overlap between alien and native Asteraceae species. We found that invasive Asteraceae species are more closely related to native Asteraceae species than are introduced and naturalized species. However, alien Asteraceae species (including introduced, naturalized, and invasive species) exhibited relatively low niche overlap with native Asteraceae species. These findings suggest that the main premise underlying Darwin's naturalization conundrum, namely, the universality of phylogenetic niche conservatism, may not hold true. Instead, our findings indicate that alien species are more likely to invade successfully when they are more closely related to native plants, exhibit less niche overlap, and maintain conservative niches during the invasion process. These findings provide new insights into the mechanisms of alien plant invasions, highlight the relationship between alien species invasions and native community vulnerability, and offer important insights into the development of effective biological invasion management strategies.

Nutrient acquisition through symbiotic ectomycorrhizal fungi is carbon (C) costly but fundamental for plant growth, community, and ecosystem functioning. Here, we examined the functions of roots and mycorrhiza with respect to nutrient uptake after artificially inducing C limitation-seven months after girdling of an ectomycorrhizal tree, Pinus taeda. Root physiological activity (measured as root nitrogen content and root exudation) declined after girdling and was accompanied with 110% and 340% increases in mycorrhizal colonization and extramatrical hyphal length, respectively. Fungi colonizing roots switched to a community characterized by higher C efficiency (lower C cost) of nutrient acquisition (CENA, the amount of nutrient acquisition per unit C cost) and lower network complexity, indicating a tradeoff between CENA and stability of the fungal community. Root transcriptome analysis suggested a shift in metabolic pathways from a tricarboxylic acid cycle decomposition of carbohydrate to lipid biosynthesis to maintain closer associations with mycorrhiza for nutrient cycling after the girdling. By integrating multi-level evidence, including root transcriptome, fungal composition, and network complexity data, we demonstrate an increased dependence on mycorrhiza for nutrient acquisition under the C limitation condition, which is likely due to a shift to fungal community with higher CENA at the cost of lower stability.

Local adaptation is critical for plant survivals and reproductions in the context of global environmental change. Heterogeneous environments impose various selection pressures that influence the fitness of organisms and leave genomic signatures during the process of adaptation to local environments. However, unveiling the genomic signatures of adaptation still poses a major challenge especially for perennials due to limited genomic resources. Here, we utilized Actinidia eriantha, a Chinese endemic liana, as a model case to detect drivers of local adaptation and adaptive signals through landscape genomics for 311 individuals collected from 25 populations. Our results demonstrated precipitation and solar radiation were two crucial factors influencing the patterns of genetic variations and driving adaptive processes. We further uncovered a set of genes involved in adaptation to heterogeneous environments. Among them, AeERF110 showed high genetic differentiation between populations and was confirmed to be involved in local adaptation via changes in allele frequency along with precipitation (Prec_03) and solar radiation (Srad_03) in native habitats separately, implying that adaptive loci frequently exhibited environmental and geographic signals. In addition, we assessed genetic offsets of populations under four future climate models and revealed that populations from middle and east clusters faced higher risks in adapting to future environments, which should address more attentions. Taken together, our study opens new perspectives for understanding the genetic underpinnings of local adaptation in plants to environmental changes in a more comprehensive fashion and offered the guides on applications in conservation efforts.