Plant Diversity最新文献

Saussurea is one of the largest and most rapidly evolving genera within the Asteraceae, comprising approximately 520 species from the Northern Hemisphere. A comprehensive infrageneric classification, supported by robust phylogenetic trees and corroborated by morphological and other data, has not yet been published. For the first time, we recovered a well-resolved nuclear phylogeny of Saussurea consisting of four main clades, which was also supported by morphological data. Our analyses show that ancient hybridization is the most likely source of deep cytoplasmic-nuclear conflict in Saussurea, and a phylogeny based on nuclear data is more suitable than one based on chloroplast data for exploring the infrageneric classification of Saussurea. Based on the nuclear phylogeny obtained and morphological characters, we proposed a revised infrageneric taxonomy of Saussurea, which includes four subgenera and 13 sections. Specifically, 1) S. sect. Cincta, S. sect. Gymnocline, S. sect. Lagurostemon, and S. sect. Strictae were moved from S. subg. Saussurea to S. subg. Amphilaena, 2) S. sect. Pseudoeriocoryne was moved from S. subg. Eriocoryne to S. subg. Amphilaena, and 3) S. sect. Laguranthera was moved from S. subg. Saussurea to S. subg. Theodorea.

DNA barcoding has been extensively used for species identification. However, species identification of mixed samples or degraded DNA is limited by current DNA barcoding methods. In this study, we use plant species in Juglandaceae to evaluate an assembly-free reads accurate identification (AFRAID) method of species identification, a novel approach for precise species identification in plants. Specifically, we determined (1) the accuracy of DNA barcoding approaches in delimiting species in Juglandaceae, (2) the minimum size of chloroplast dataset for species discrimination, and (3) minimum amount of next generation sequencing (NGS) data required for species identification. We found that species identification rates were highest when whole chloroplast genomes were used, followed by taxon-specific DNA barcodes, and then universal DNA barcodes. Species identification of 100% was achieved when chloroplast genome sequence coverage reached 20% and the original sequencing data reached 500,000 reads. AFRAID accurately identified species for all samples tested after 500,000 clean reads, with far less computing time than common approaches. These results provide a new approach to accurately identify species, overcoming limitations of traditional DNA barcodes. Our method, which uses next generation sequencing to generate partial chloroplast genomes, reveals that DNA barcode regions are not necessarily fixed, accelerating the process of species identification.

Alpine plants possess unique traits to adapt alpine environments. Whether leaf trait relationships of alpine plants can be captured by the two trait dimensions of organ size and resource economics is unknown. We hypothesized that, beyond the trait dimensions of leaf size and resource economics, non-structured carbohydrates (NSC) would reflect a dimension of cold-tolerance in alpine plants. To test this hypothesis, we measured 12 leaf traits critical to leaf construction and growth in 143 species across 7 sites ranging from alpine steppes to alpine meadows along an environmental gradient on the Tibetan Plateau. Furthermore, a cold resistance experiment was conducted at one of these sites to estimate the lethal temperature causing 50% frost damage (LT₅₀) of 11 alpine species. The majority of variations in 12 leaf traits of alpine plants were captured by three trait axes, in which leaf carbon (LCC) and NSC (including leaf starch; LSC and leaf soluble sugars; LSS) were clustered in a new dimension (PC3) beyond leaf size and structure, and resource economics. Although LCC, LSC and LSS all showed negative correlations with mean annual temperature, a significant negative correlation was only found between LSS and LT₅₀. It indicated that PC3 was able to reflect the cold-tolerance of alpine plants to some extent, in which LSS was the most critical trait. The storage and transformation of NSC under stressful conditions could reflect a dimension of long-term metabolic adaptation and cold-tolerance, which is an extension of the resource-utilization strategy beyond construction cost and growth.

The global rise in animal protein consumption has significantly amplified the demand for fodder. A comprehensive understanding of the diversity and characteristics of existing fodder resources is essential for balanced nutritional fodder production. This study investigates the diversity and composition of fodder plants and identifies key species for cattle in Zhaotong City, Yunnan, China, while documenting indigenous knowledge on their usage and selection criteria. Ethnobotanical surveys were conducted in 19 villages across seven townships with 140 informants. Data were collected through semi-structured interviews, free listing, and participatory observation, and analyzed using Relative Frequency Citation. A total of 125 taxa (including 106 wild and 19 cultivated) were reported. The most cited family is Poaceae (27 taxa, 21.43%), followed by Asteraceae (17 taxa, 13.49%), Fabaceae (14 taxa, 11.11%), Polygonaceae (9 taxa, 7.14%) and Lamiaceae (4 taxa, 3.17%). The whole plant (66.04%) and herbaceous plants (84.80%) were the most used parts and life forms. The most cited species were Zea mays, Brassica rapa, Solanum tuberosum, Eragrostis nigra, and Artemisia dubia. Usage of diverse fodder resources reflects local wisdom in managing resource availability and achieving balanced nutrition while coping with environmental and climatic risks. Preferences for certain taxonomic groups are due to their quality as premier fodder resources. To promote integrated crop-livestock farming, we suggest further research into highly preferred fodder species, focusing on nutritional assessment, digestibility, meat quality impacts, and potential as antibiotic alternatives. Establishing germplasm and gene banks for fodder resources is also recommended.

Global warming leads to snow cover loss in the alpine ecosystem, exposing seeds to extreme diurnal temperature fluctuations during the growing season. The risk of freezing increases as seeds have increased moisture content. Studying the survival mechanisms of seeds at low temperatures can help analyze changes in alpine meadow populations and target conservation efforts. Here, we used three species of Poaceae as a model to understand freezing stress. Fully imbibed Elymus dahuricus, Festuca elata, and Lolium multiflorum seeds were subjected to programmed cooling at fast and slow rates (-1.0/0.05 °C/min) and then assessed for survival. Differential Scanning Calorimetry was used to analyze thermal transitions during cooling. HE-stained paraffin sections and a Transmission Electron Microscope were employed to observe internal morphology and ultrastructural changes. E. dahuricus seeds exhibited greater tolerance to low temperatures than those of the other two species, with an LT₅₀ of approximately -20 °C for both cooling rates and maintained relatively intact ultrastructure. The observed the low-temperature exotherm (LTE) correlated with seed survival, with viability decreasing extensively below LTE. Fast cooling caused fewer changes to seed morphology and ultrastructure than slow cooling, suggesting that the primary survival mechanism during fast cooling is freezing avoidance through supercooling. Seeds exhibited greater freeze tolerance under slow than fast cooling, primarily by migrating intracellular water to extracellular spaces where it froze, causing considerable damage to cell ultrastructure and forming apparent cavities in some seeds.

Evolutionary transitions from sexual to asexual reproduction should have significant influences on genetic divergence and polymorphism at the genome level. Plant lineages with diverse reproductive systems provide opportunities to investigate this question using comparative approaches and studies of molecular evolution. We investigated evidence for differences among the transcriptomes of 19 Dioscorea species (wild yams) with diverse reproductive systems. These included sexual species, those that propagate primarily by bulbils, and those with mixed sexual and asexual reproductive modes. We examined how transitions between these reproductive systems affected between-species divergence and within-species polymorphism. Primarily asexual species exhibited a reduced efficacy of natural selection and accumulation of deleterious mutations for both divergence and polymorphism. In contrast, species with mixed reproductive strategies involving both seed and clonal reproduction showed no evidence of an increased fixation of harmful mutations at the divergence level, while an accumulation of genetic load present in polymorphism was evident. Our study indicates that the genetic consequences of evolutionary transitions from sexual to predominantly clonal reproduction is likely to depend on both the duration and extent of asexuality occurring in populations.

Root anatomical traits play an important role in understanding the link between root physiological function and ecological process. To determine how plants change root anatomical traits to adapt to distinct environments, we measured four key root anatomical traits-stele diameter (SD), cortex thickness (CT), root diameter (RD), and the stele to root diameter ratio (SDRD)-of first-order roots of 82 species collected from different vegetation zones along a 2000 m altitudinal gradient on the northern slope of Taibai Mountain. Compared with other altitudes, plants located in temperate birch and fir forests had thinner SD, CT, RD, and SDRD. We found that elevational variation in root anatomical traits could largely be explained by phylogenetic taxonomy (clade). In addition, changes in SD were driven by soil bulk density, whereas variations in CT and RD were influenced by soil available nitrogen. When phylogenetic factors were removed from our analysis, allometric relationships between RD and root anatomical traits (SD and CT) were observed across different altitudes. Our study reveals the influence of phylogeny and environment on the elevational variation in root anatomical traits and further supports the allometric relationship between root anatomical traits (SD and CT) and RD. These findings enhance our understanding of the evolutionary and adaptive mechanisms of root anatomical structures, providing a basis for predicting how root anatomical traits respond to global changes.

Studies on plant diversity are usually based on the total number of species in a community. However, few studies have examined species richness (SR) of different plant life forms in a community along large-scale environmental gradients. Particularly, the relative importance (RIV) of different plant life forms in a community and how they vary with environmental variables are still unclear. To fill these gaps, we determined plant diversity of ephemeral plants, annual herbs, perennial herbs, and woody plants from 187 sites across drylands in China. The SR patterns of herbaceous plants, especially perennial herbs, and their RIV in plant communities increased with increasing precipitation and soil nutrient content; however, the RIV of annual herbs was not altered along these gradients. The SR and RIV of ephemeral plants were affected mainly by precipitation seasonality. The SR of woody plants had a unimodal relationship with air temperature and exhibited the highest RIV and SR percentage in plant communities under the harshest environments. An obvious shift emerged in plant community composition, SR and their critical impact factors at 238.5 mm of mean annual precipitation (MAP). In mesic regions (> 238.5 mm), herbs were the dominant species, and the SR displayed a relatively slow decreasing rate with increasing aridity, which was mediated mainly by MAP and soil nutrients. In arid regions (< 238.5 mm), woody plants were the dominant species, and the SR displayed a relatively fast decreasing rate with increasing aridity, which was mediated mainly by climate variables, especially precipitation. Our findings highlight the importance of comparative life form studies in community structure and biodiversity, as their responses to gradients differed substantially on a large scale.

The expansion of road networks in recent decades has drawn considerable attention due to its impact on biodiversity in high-altitude ecosystems. Here, we conducted a comprehensive field survey to investigate the effects of road disturbance on plant diversity in alpine grasslands on the Tibetan Plateau. Our results indicate that road disturbance caused no significant changes in species richness, Shannon-Wiener's diversity, or Simpson's diversity, and the alteration in species composition was limited. These findings demonstrate the robust resistance of alpine grassland plant diversity to road disturbance. Plant diversity exhibited more resistance to road disturbance in regions with more hostile environments, such as plateau sub-frigid regions and alpine steppes. Our study suggests that road construction in the Tibetan Plateau poses limited risk to plant biodiversity.

The genus Salix is a common component of the Northern Hemisphere dendroflora with important ecological and economic value. However, taxonomy and systematics of Salix is extremely difficult and relationships between main lineages, especially deep phylogenies, remain largely unresolved. In this study, we used genome-skimming, plastome assembly, and single-copy orthologs (SCOs) from 66 Salix accessions, along with publicly available plastome and sequence read archive (SRA) datasets to obtain a robust backbone phylogeny of Salix, clarify relationships between its main lineages, and gain a more precise understanding of the origin and diversification of this species-rich genus. The plastome and SCO datasets resolved Salix into two robust clades, with plastome-based phylogenies lacking inner resolution and SCO offering fully resolved phylogenies. Our results support the classification of Salix into five subgenera: Salix, Urbaniana, Triandrae, Longifoliae and Vetrix. We observed a significant acceleration in the diversification rate within the Chamaetia-Vetrix clade, while Salix exhibited increased rates of diversification spanning from the early Oligocene to the late Miocene. These changes coincided with contemporaneous tectonic and climate change events. Our results provide a foundation for future systematic and evolutionary studies of Salix. Additionally, we showed that genome skimming data is an efficient, rapid, and reliable approach for obtaining extensive genomic data for phylogenomic studies, enabling the comprehensive elucidation of Salix relationships.