Wuhan Botanical Garden

Continental chemical weathering plays a crucial role in the regional and global carbon budgets. However, relevant research on tropical volcanic islands is still limited, particularly the influences of human activities on surficial chemical weathering, which remain scarce. This study analyzed the water geochemistry and dissolved inorganic carbon isotope (δ13CDIC) of the Changhua River draining Hainan Island, aiming to quantitatively elucidate the seasonal CO2 budgets at the catchment scale. We found that the major ions in the river were from atmospheric precipitation (6.79%), anthropogenic input (11.68%), carbonate weathering (41.96%), and silicate weathering (39.56%). The silicate weathering rate and the carbonate weathering rate were calculated as 16.91 t km–2 yr–1 and 30.68 t km–2 yr–1, respectively, resulting in CO2 consumption of 307.82 × 103 mol km–2 yr–1 and 400.95 × 103 mol km–2 yr–1. Considering sulfuric acid- and nitric acid-driven weathering reactions, the catchment became a net source of CO2 on a geological time scale. Furthermore, the drivers of chemical weathering and associated CO2 budget were deciphered. The significant positive correlations among chemical weathering fluxes, acids, and land uses quantitatively emphasized that the chemical weathering of CO2 budgets was largely disturbed by anthropogenic activities. This study showed that integrating river water geochemistry and geographical parameters could achieve a deep understanding of catchment weathering CO2 budgets and potential driving mechanisms.

Abstract Transposable elements (TEs) are dynamic components of eukaryotic genomes and a major source of structural and regulatory variation, yet their contribution to ecological adaptation over evolutionary time remains unresolved. This uncertainty is particularly acute in species that occupy broad environmental niches despite chronically low nucleotide diversity, where conventional models predict limited adaptive potential. Here we show that ancient TE polymorphisms underpin global ecological adaptation in Spirodela polyrhiza , one of the smallest flowering plants with low genome-wide nucleotide diversity. Most TE polymorphisms predate continental population divergence. Cold-season temperature emerges as the dominant selective axis, with adaptive signals overwhelmingly associated with TE polymorphisms rather than SNPs. These adaptive TEs bear signatures of selection on standing variation and are embedded in genomic regions shaped by relaxed purifying selection rather than recent hard sweeps. Our results reveal how ancient TE variation sustains ecological adaptation despite chronically depleted nucleotide diversity, resolving a longstanding evolutionary paradox. One sentence summary How species adapt with little genetic diversity is a longstanding evolutionary puzzle solved by ancient transposon insertions

Cheilosoideae is the smallest and earliest-diverging of the four subfamilies of Euphorbiaceae, with seven species grouped in two morphologically similar paleotropical genera, Cheilosa and Neoscortechinia. The subfamily is distinguished by its unusual echinate pollen but their relationships remain poorly understood, with limited taxon sampling in prior evolutionary analyses. The present study, using newly generated whole plastome and nuclear ribosomal DNA (nrDNA) datasets, provides new insights into their molecular and morphological evolution. Our findings on the seven assembled Cheilosoideae plastomes reveal typical tetrad structure and length variation, with sizes ranging from 160,197 bp to 163,210 bp. Structural variations among plastomes generated distinct hotspots of repetitive sequences, particularly within tandem repeats and SSRs. Our phylogenetic analyses based on the plastome dataset resolved the four subfamilies (Cheilosoideae, Acalyphoideae, Crotonoideae, and Euphorbioideae) of Euphorbiaceae in successive sister relationships, although this result was partly inconsistent with an alternative topology based on the nrDNA dataset. Our study provides the first species-level phylogenetic framework for the Cheilosoideae. Both plastid and nuclear analyses strongly support an unexpected, slightly nested position of Cheilosa within a paraphyletic Neoscortechinia. Biogeographic analyses infer that Cheilosoideae probably originated from Southeast Asia and diversified since Middle Miocene (ca. 12.77 Ma). These results offer novel perspectives on the evolutionary history and biogeographic origins of Cheilosoideae within the Euphorbiaceae.

Touch-sensitive stigmas (TSSs), specialized receptive structures in angiosperms, dynamically respond to mechanical stimulation or pollen deposition. The typical sequence comprises temporary closure, reopening, and permanent closure, which optimize pollen capture, retention, and fertilization success. However, the specific environmental and pollination-related factors regulating these phases are unexplored. Here we systematically investigated the association of environmental (temperature and humidity) and pollination-related factors (amount of pollen deposited [load], position of pollen tube, and growth rate of pollen tube) with the temporal dynamics of stigma movements in Mazus miquelii, a species with TSS. Temporary closure and reopening were primarily associated with temperature and were independent of the pollen load. In contrast, permanent closure was strongly correlated with the pollen load and position and growth rate of pollen tube. Furthermore, temporary closure and reopening time were negatively correlated, although neither were significantly correlated with permanent closure time. Rapid temporary closure and reopening events were primarily associated with environmental cues, whereas irreversible permanent closure was associated with pollination-related signals. These advances in our understanding of the ecological regulation of TSS behavior provide a foundation for future studies into the physiological and molecular mechanisms of touch sensitivity of stigmas.

Siberian kale (Brassica napus subsp. pabularia, AACC, 2n = 38) is a distinct subspecies of B. napus, characterized by its deeply lobed leaves and primarily cultivated as a nutritious leafy vegetable. Here, we present a chromosome-level genome of Beta, a Siberian kale variety, integrating Illumina short reads, PacBio HiFi long reads, and Hi-C data. The final assembly size is 1,078.8 Mb, with a scaffold N50 of 57.5 Mb and a genome BUSCO completeness of 99.7%. 954.0 Mb (88.4%) of sequences were successfully anchored to 19 pseudo-chromosomes. The configuration of Beta genome chromosomes is consistent with the distribution of ten A subgenome and nine C subgenome chromosomes in rapeseed. In total, 98,882 protein-coding genes were predicted ab initio in the Beta genome, with an average gene length of 1,997 bp, and 90,415 (91.44%) genes were functionally annotated. Overall, the high-quality genome provides a valuable resource for bridging current knowledge gaps and offers key genetic insights into deeply lobed leaf formation and improvement of Brassica crops.

Mitochondrial genome evolution(MGE) in flowering plants is quasi-intertwined-dynamic. MGE is driven via mutational pressures, translational selection, and functional constraints. However, unveiling the intra- and inter-genomic interplay governing evolutionary drives remains challenging. We investigate MGE-dynamic across twelve Gentianales species, revealing distinct codon usage patterns influenced by opposing evolutionary forces. While the first and second codon positions are highly conserved, the third codon positions show significant variability (27.7% - 45.8%), reflecting diverse selective pressures. Multi-dimensional analyses, including ENc-GC3s plots, neutrality plots, and PR2 bias, indicate that natural selection predominantly governs codon usage, outweighing mutational biases. Key findings include, non-significant correlations between GC12 and GC3 (R2 ≤ 0.21), suggesting minimal mutational impact on genome composition; ENc-GC12 analysis showing codon optimization results from both selection and mutation; and PR2-plot analysis highlighting a preference for T- and G-ending codons, indicative of translational efficiency constraints. Gene-specific analyses of substitution rates (dN, dS, and dN/dS ) uncover heterogeneous selective landscapes, with genes such as atp, ccm, nad, and rps exhibiting signatures of positive selection. Substantial mutually offsetting dynamics between T3s and C3s (r = - 0.73), coupled with strong correlations between G3s and translational-efficiency indices (CAI: r = 0.69; CBI: r = 0.65), underscore that third-codon biases optimize translation. Evolutionary rates (dS and dN/dS ) show positive correlations with GC3 content (r = 0.45 and r = 0.33, respectively), indicating the influence of nucleotide composition on synonymous substitutions. Thus, these results reveal the interplay of the mutation-selection balance in non-recombining genomes and offer new perspectives on mitochondrial diversity in flowering plants.