Abiotic stresses like heat, salinity, and drought profoundly influence plant development and flowering. Beyond altering gene networks, environmental stresses can activate transposable elements to generate genetic and epigenetic variation. For example, the heat-responsive retrotransposon AtCOPIA78 (ONSEN) mobilizes in RNA-directed DNA methylation (RdDM)-defective backgrounds. Although ONSEN mobilization generates heritable phenotypic variation, its role in flowering remains unclear. In this study, we examined the impact of stress-activated ONSEN mobilization on flowering-time regulation using nrpd1 mutant backgrounds. By screening ONSEN-mobilized nrpd1 populations, we identified an early-flowering mutant, designated YUNOHANA which flowered earlier than the parental nrpd1 mutant despite sharing the same RdDM defect. The early-flowering phenotype was associated with reduced expression of the floral repressor FLOWERING LOCUS C (FLC) and increased expression of the floral activator FLOWERING LOCUS T (FT). Genome-wide analysis identified multiple ONSEN insertion sites in yunohana (yuno), though none resided within known flowering-time regulatory genes. Segregation-based genotyping of early-flowering F2 plants prioritized a subset of candidate loci, including insertion sites near AT1G50130, AT1G07240, and AT3G22100, although no single tested insertion fully co-segregated with the phenotype. Transcriptome profiling revealed that yuno retained a global expression pattern largely like that of nrpd1, with differences restricted to few loci. Furthermore, ONSEN transcript and extrachromosomal DNA levels were reduced in yuno than nrpd1, indicating suppressed transposon activity following mobilization. Together, our findings suggest that stress-activated ONSEN mobilization can be associated with heritable developmental variation without widespread transcriptional disruption and identify candidate loci potentially linked to flowering-time regulation.

Cold stress represents a significant environmental challenge that constrains the development of the grapevine industry. The basic helix-loop-helix (bHLH) transcription factor family plays pivotal regulatory roles in plant growth, development, and stress responses. This study identifies a novel member of the bHLH family, referred to as VabHLH015, isolated from Vitis amurensis 'Zuoshan-1'. The physicochemical properties, conserved domains, and evolutionary relationships of VabHLH015 were thoroughly analyzed. Additionally, Arabidopsis thaliana and Vitis vinifera 'Chardonnay' calli overexpressing VabHLH015 were generated to evaluate their cold stress tolerance. Amino acid sequence analysis indicated that the VabHLH015 protein comprises 491 amino acids, containing the bHLH-MYC_N and bHLH_AtAIB_like domains. Tissue-specific expression analysis demonstrated differential expression of VabHLH015 across various grapevine organs, with transcript levels markedly increasing in response to low temperature and multiple exogenous hormones. Subcellular localization confirmed that VabHLH015 is a nuclear protein. A transcriptional activation assay showed that it possesses autoactivation activity. Functional analyses revealed that transgenic A. thaliana and grape calli overexpressing VabHLH015 exhibited heightened sensitivity to cold stress. In comparison to wild-type controls, these transgenic lines displayed significantly elevated malondialdehyde (MDA) content and electrolyte leakage, alongside diminished activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as reduced proline (Pro) accumulation. Moreover, the expression levels of several cold-responsive genes were significantly downregulated in the transgenic lines. In summary, the overexpression of VabHLH015 attenuates plant tolerance to low temperatures by modulating the expression of cold tolerance-related genes and antioxidant enzyme activities. This study offers a novel candidate gene and provides a theoretical framework for elucidating the molecular mechanisms underlying cold tolerance, facilitating the breeding of cold-tolerant grapevine varieties.

Floral merism, the number of organs per whorl, is a conserved trait in angiosperms and has significant implications for plant reproduction. Solanum (Solanaceae) presents typically pentamerous flowers, while some species can present meristic variations. S. hexandrum is a species with typical hexamerous flowers, which represents a fixed trait in some population, while its closely related species S. sublentum exhibit the typical pentamerous flower. Importantly, both species show meristic lability, indicating that floral organ number is flexible within the group. This study investigates the developmental basis for merism variation in these species by comparing the floral ontogeny across three populations of S. hexandrum and S. sublentum. We used scanning electron microscopy, Nano-CT analysis and floral anatomy to analyse the meristem size, floral development and floral vascularization to understand the pressures influencing this morphology and its impacts on floral architecture. We found that merism variations (in a range of tetramery to heptamery) is strongly correlated with floral meristem size. Populations with larger meristems exhibited supernumerary organs, while those with smaller meristems showed subnumerary organs or stable pentamery. The meristic changes were predominantly isomerous across the whorls. Flower ontogenesis also differed among populations and species, directly influencing the final flower form. Our result demonstrates that merism size and spatio-temporal developmental constraints are key factors shaping meristic lability in Solanum. These results improve the knowledge about floral diversification and meristic variation in the genus and can support future work aiming to study floral evolution and unusual morphologies in Solanum.

Cadmium (Cd) is a highly toxic heavy metal that poses a serious threat to plant growth and the quality of agricultural and animal products. Therefore, elucidating the response and regulatory mechanisms of plants to Cd stress is essential for controlling the safety of agricultural and animal products at the source. In this study, we used a Cd-tolerant alfalfa cultivar, Medicago sativa 'Zhaodong' (ZD), and a Cd-sensitive cultivar, M. sativa 'Zhongmu No.1' (ZM), to investigate their differential responses to Cd stress in terms of morphology, photosynthetic function, and oxidative damage through combined physiological and RNA-Seq analyses. The results indicated that Cd stress inhibited leaf growth and photosynthetic function, and increased oxidative damage in alfalfa. The Cd-tolerant cultivar ZD exhibited greater tolerance compared to the Cd-sensitive cultivar ZM. RNA-Seq analysis revealed that the differentially expressed genes (DEGs) between the two cultivars under Cd stress were predominantly enriched in photosynthesis-related KEGG and GO pathways. Based on RNA-Seq and weighted gene co-expression network analysis (WGCNA), the MEgreen module exhibiting the highest correlation with physiological traits such as biomass and photosynthetic function was identified. The DEGs in this module were predominantly enriched in pathways related to photosynthesis and plant hormone signal transduction. Furthermore, a key gene, MsERF15, which regulates photosynthesis and ROS metabolic homeostasis in alfalfa under Cd stress, was identified. Although heterologous expression of MsERF15 significantly increased plant height in transgenic tobacco, it markedly reduced Cd stress tolerance, particularly by decreasing chlorophyll content and photochemical reaction center activity in the leaves under Cd stress, as well as elevating ROS accumulation. The potent growth-promoting effect of MsERF15 may represent a key factor contributing to its reduced Cd stress tolerance. In summary, our findings demonstrate that MsERF15 negatively regulates Cd stress tolerance in alfalfa. These results provide new insights into the adaptation mechanisms of alfalfa under Cd stress and offer a novel target for genetic improvement of Cd resistance in this important forage crop.

Myrteae is a tribe that encompasses the majority of Neotropical Myrtaceae diversity, with the subtribe Eugeniinae being the most species-rich, including the genera Eugenia (1,243 spp.) and Myrcianthes (41 spp.). Morphologically, the group presents complex taxonomy, particularly in Eugenia, which is subdivided into 11 infrageneric sections. The search for new morphological characters is crucial for delimiting and identifying species and infrageneric groups. In this context, colleters (glandular structures involved in the protection of leaf and floral primordia) remain poorly explored. This study investigated the presence, morphology, and distribution of colleters across Eugeniinae to assess their taxonomic relevance. A total of 221 Eugenia species, representing all infrageneric sections, and seven Brazilian Myrcianthes species were analyzed. Herbarium specimens were used for morphometric and scanning electron microscopy analyses, as well as for correlations between colleters and other variables. Results revealed extensive variation in colleter morphology and distribution across vegetative and reproductive axis, with euriform shapes predominating in Eugenia and conical forms in Myrcianthes. Colleters were mostly associated with drier environments and were absent in glabrous species, suggesting a relationship with indumentum. Morphometric analyses indicated overlap among most groups, except for E. sect. Schizocalomyrtus, E. sect. Racemosae, and non-American Eugenia species, which exhibited distinct patterns. Overall, homogeneous colleters (the predominant type in the subtribe) emerged as promising auxiliary diagnostic characters for Eugeniinae taxonomy, particularly when combined with other morphological traits.

HSFA2 is a key regulator of acquired thermotolerance after mild-heat priming, but whether volatile-triggered priming depends on this pathway remains unclear. Here, we examined thermotolerance induced by the reactive green leaf volatile trans-2-hexenal (T2H) in Arabidopsis thaliana Col-0 and an hsfa2 T-DNA insertion mutant. Seedlings were primed with mild heat or a 30-min T2H pulse, recovered for 2 days, and challenged with lethal heat. T2H pretreatment improved survival in both genotypes. Survival analysis and image-based quantification of projected green area showed that T2H-supported recovery was retained in hsfa2, whereas recovery after mild-heat priming was reduced. Total chlorophyll content showed the same genotype-dependent pattern: it was lower in hsfa2 than in Col-0 after mild-heat priming but did not differ between genotypes after T2H. Early reverse-transcription quantitative PCR (RT-qPCR) analysis showed that transcript levels of HSFA1A, HSFA1B, HSFA1D, HSFA1E, and HSP101 did not correlate with the observed survival response. In a separate recovery-period analysis, HSP101 transcript abundance in hsfa2 was significantly lower than in Col-0 after both priming treatments, with the larger reduction after T2H despite strong mutant protection. RNA sequencing (RNA-seq) revealed distinct transcriptional responses between heat and volatile priming: mild heat induced broad transcriptome remodeling, whereas T2H induced a more selective stress-associated response enriched in detoxification- and redox-associated, immune-associated, and hypoxia-like transcript categories. In hsfa2, T2H was also associated with increased transcript abundance of WRKY- and MAPK-associated stress-signaling genes relative to heat priming. These findings suggest that reactive volatile priming may support thermotolerance through HSFA2-independent stress-signaling pathways.

Coleanthus subtilis is a globally rare therophyte growing on exposed bottoms of water reservoirs and riverbanks. Despite its small size and ephemeral nature, it shows a potential to conquer new areas and can dominate phytocoenoses of small wetland therophytes and pioneer the land interface zones of lakes, pools and ponds. However, features enabling its spread and dominance in patches remain poorly understood. Also, the composition of biologically active compounds of the species has not been characterized in detail so far. Therefore, we assessed the species allelopathic potential as referred to the presence of biologically active compounds and ecotoxicity. Several natural products belonging to benzoxazinone derivatives, phenolic compounds, and carboxylic acids were identified in this species, which are likely to have allelopathic potential. The results of phytotoxic tests showed that water extract of C. subtilis induced a delay in germination of the model plant Sinapis alba, and, at concentrations higher than 4%, caused a significant reduction in the percentage of germinated seeds. In addition, root growth of S. alba was inhibited at concentrations of the extract greater than 4%. Oppositely, the growth of model plant hypocotyl was stimulated by low concentrations (< 4%) of the C. subtilis water extract. By showing the allelopathic potential, our results shed new light on the C. subtilis performance and absolute dominance in some patches of muddy vegetation.

Transitions from an outcrossing to a selfing mating system may represent an advantage during plant invasions, enabling the production of offspring even in cases of unstable pollinator environments or mate limitation. In this study, we explore the shifts in floral traits associated to the mating system across the distribution range of Datura stramonium, a cosmopolitan invasive weed native from Mexico and surrounding regions. We recorded seven floral traits of 1,945 flowers from 77 populations (12 native and 65 non-native) throughout the world distribution range to analyze their differentiation between the native and non-native ranges. Non-native populations of D. stramonium presented lower herkogamy than native populations, in agreement with the hypothesis of reproductive assurance under non-reliable pollinator environments. Corollas were unexpectedly larger in the non-native than in the native range, which could be attributed to high nutrient and water inputs in agroecosystems, the most common habitat of non-native populations. The phenotypic variation within populations was lower in the non-native range, which is congruent with the occurrence of founder events during the introduction or subsequent drift. Floral color showed a significant differentiation between native and non-native populations, probably due to founder events. The lack of association between floral color and herkogamy indicates that their differentiation between ranges is due to different and independent processes. Future studies involving experimental populations grown under different environmental conditions at each range, and population genetic and phylogeographic studies, will help to identify the selective factors and evolutionary processes determining the phenotypic patterns depicted across native and non-native populations of D. stramonium.

Escalating climate-induced drought events are increasingly pushing terrestrial plants toward their physiological limits, challenging their growth and ecological acclimation. Metabolic reprogramming represents a critical adaptive strategy under water deficit, in which aspartate aminotransferase (AspAT) serves as a key node by modulating carbon-nitrogen flux, energy metabolism, and amino acid biosynthesis. Although AspAT genes have been implicated in abiotic stress responses in herbaceous species, their roles in woody plants remain poorly characterized. Here, we identified multiple drought-responsive AspAT family members in poplar and further characterized the function of AspAT10. Transgenic poplars overexpressing AspAT10 (OE) exhibited higher drought tolerance than wild-type (WT) controls, maintaining higher growth rates, greater biomass accumulation, and improved leaf water status under drought conditions. Consistent with these phenotypes, OE lines displayed elevated relative water content, photosynthetic performance, and lignin accumulation relative to WT plants. Transcriptome analysis revealed that AspAT10 overexpression was associated with the upregulation of genes involved in amino acid metabolism, as well as pathways related to cuticular wax formation. These findings suggest that AspAT10 may contribute to drought responses through coordinated regulation of metabolic and transcriptional processes, thereby supporting plant growth under drought stress.

Taraxacum kok-saghyz (T. kok-saghyz) is considered a highly promising alternative source of natural rubber (NR), as its roots synthesize high-molecular-weight NR comparable to that produced by Hevea brasiliensis. The basic helix-loop-helix (bHLH) family of transcription factors (TFs) plays crucial roles in plant organogenesis, hormonal signal transduction, and the regulation of secondary metabolism. This study aimed to systematically identify TkbHLH family members and to elucidate their potential functions in responding to methyl jasmonate (MeJA) and regulating root development. Based on the T. kok-saghyz genome, 172 TkbHLH members were identified and phylogenetically classified into 16 subfamilies. Among these, 37 genes were selected due to their significant induction by MeJA. Sequence analysis confirmed all encoded proteins contain the conserved bHLH domain. Subcellular localization verified nuclear localization of five core TkbHLH proteins. Interactions were shown by yeast two-hybrid and bimolecular fluorescence complementation, revealing these proteins form homodimers and heterodimers. Notably, a specific interaction was detected between TkbHLH162 and TkHMGS1, a key enzyme in the mevalonate (MVA) pathway, suggesting a potential molecular link between JA signaling and the rubber biosynthesis precursor pathway. Functional characterization via overexpression assays showed that selected TkbHLH genes significantly either promoted or inhibited root elongation. In summary, this study presents the first systematic characterization of the bHLH TF family in T. kok-saghyz, elucidating its involvement in JA signal response, protein interaction networks, and root development regulation. These findings provide a crucial foundation for further investigation into the molecular mechanisms by which TkbHLH TFs influence root morphogenesis and NR biosynthesis in T. kok-saghyz.

Herbarium specimens are physical, verifiable records that form the basis of taxonomic knowledge and biodiversity research. Their large-scale digitization has produced extensive collections of high-resolution images and associated specimen metadata, creating conditions in which artificial intelligence (AI) can play an important role in plant taxonomy, collection management, and ecological research. Early AI applications have primarily focused on automated species identification based on individual specimen images. Although increasingly accurate, such approaches remain limited by their emphasis on single-specimen label prediction and by treating identification outputs as final analytical decisions. Recent methodological advances-including segmentation-based preprocessing, automated trait extraction, structured extraction of label data, detection of potentially misidentified specimens, and multimodal integration of visual, textual, and genetic information-extend AI applications beyond species identification toward broader analytical frameworks, encompassing taxonomic interpretation as well as ecological and biodiversity research. In these approaches, specimens are placed within a shared analytical space, and identification results are used to support comparisons across multiple specimens rather than being treated as final decisions for single individuals. This multi-specimen perspective enables quantitative examination of species boundaries, morphological variation, data inconsistencies, and taxonomic stability within curated collections. In this context, AI serves not as an ultimate decision-maker but as a decision-support tool embedded in expert-guided workflows and biodiversity knowledge infrastructures. These developments can be summarized as Integrative Taxonomic AI, an approach that employs learned morphospaces to interpret and refine taxonomic categories by integrating multimodal evidence and curated specimen data under expert guidance.

High-temperature stress induced by global warming can hinder the production of commercial cultivars in mangoes (Mangifera indica L.). Selecting cultivars with high-temperature tolerance is essential. We evaluated damage to leaf cell membranes as an indicator of high-temperature tolerance in mangoes. An evaluation method using leaf-electrolyte leakage was established by comparing the temperature responses of several genotypes, and then applied to 100 genotypes, including major cultivars worldwide. Genotypic differences in high-temperature tolerance were verified based on the climate of selection and production areas. Logistic regression analysis was performed on datasets from two different years for each genotype, with temperature (40-55 °C) as the explanatory variable, and the calculated Injury Index as the target variable. The obtained regression equations were highly accurate (R[2] > 0.9; RMSE < 10) for each genotype and year. Furthermore, a strong positive correlation (Spearman's rank correlation coefficient > 0.8) was obtained between the pair of temperature conditions and the maximum curvature on the regression curve (Cmax) for two different years for each genotype, confirming the validity of the evaluation method. Up to ≈ 6 °C genotypic difference was observed in the mean Cmax values. Cultivars from warm and humid Southeast Asia tended to have a higher cell membrane tolerance than those from dry India. Florida cultivars, mostly pedigreed from Southeast Asia and India, were widely allocated from high to low. We ranked 100 mango genotypes based on the high-temperature tolerance of leaf cell membranes, demonstrating reasonable consistency with the climatic conditions of their selection and production areas.