Plant Biology最新文献

Understanding inter- and intraspecific interactions is central to community ecology. Using data from two censuses of a subtropical secondary forest in Huangshan, China, we analysed survival rate for over 54,000 saplings across 83 species. We quantified four neighbourhood density indices, conspecific (CI), heterospecific (HI), phylogenetic (PhyI), and functional (FunI), to test how neighbour density influences tree survival. In parallel, we calculated neighbourhood diversity along species, phylogenetic, and functional axes to test how neighbour diversity shapes species' survival probabilities spanning four different spatial scales. Generalized linear mixed models revealed that HI and FI significantly decreased survival, highlighting intense interspecific competition in early successional stages. In contrast, PhyI positively affected survival, suggesting habitat filtering among related species. Neighbourhood diversity exhibited scale-dependent effects. Finally, we identified species with high specific leaf area and phosphorus content grew faster but experienced higher mortality. These findings underscore the importance of incorporating phylogenetic and functional neighbourhood metrics to understand demographic processes and community assembly, particularly in recovering forest ecosystems.

Specific generation of reactive oxygen species (ROS) is important for signalling and defence in many organisms. In plants, different types of ROS serve useful biological functions in the extracellular space (apoplast), influencing polymer structures as well as signalling during immune responses. The current knowledge of apoplastic ROS dynamics is limited, as dynamic monitoring of extracellular redox processes in vivo remains difficult. We employed evolutionary distant land plant model species from bryophytes and flowering plants to test whether the genetically encoded redox biosensor roGFP2-Orp1 can be used to assess extracellular redox dynamics. Secreted roGFP2-Orp1 can provide information about local diffusion barriers and protein cysteinyl oxidation rate in the apoplast, after pre-reduction. Observed re-oxidation rates were slow - within the range of hours. Compared to Physcomitrium patens, re-oxidation in Arabidopsis thaliana was faster and increased after triggering an immune response. Comparing roGFP2-Orp1 signals in tip-growing P. patens protonema and Nicotiana tabacum pollen tubes, we consistently find no intracellular redox gradient, but a partially reduced extracellular sensor in pollen tubes. Our data indicate differences in extracellular oxidative processes between species and within a species, depending on cell type and immune signalling.

The evolutionary limits to generalization in plant pollination systems are often determined by trade-offs in which adaptations to one set of flower visitors reduces the effectiveness of another set of visitors. A key question is whether flowers can be pollinated equally effectively during the day and the night, given that the attractants for diurnal visitors are expected to be very different to those for nocturnal visitors. To address this question, we investigated the pollination system of the mass-flowering desert geophyte Nerine laticoma (Amaryllidaceae) over 2 years. We measured floral traits, including colour, scent, dimensions, floral rewards, visitation and reproductive traits. Finally, we exposed a subset of flowers exclusively to either diurnal or nocturnal visitors to establish their relative contributions to reproduction. Nerine laticoma has relatively open flowers, with exposed nectar, attracting a wide diversity of pollinators, including bees, butterflies, nocturnal settling moths and hawkmoths. We established that N. laticoma is reliant on pollinators for seed production. Flowers exposed only during the day set a similar number of seeds to those exposed only during the night, indicating that the plant is effectively pollinated by both diurnal and nocturnal animals. The results highlight the importance of multiple pollinators and their contribution to reproductive success in desert environments with variable pollinator communities. The contribution of all possible pollinators in a system, including frequently overlooked nocturnal visitors, should thus be taken into account.

Nepenthes, a major genus of carnivorous plants, secrete floral and extrafloral nectars (FN and EFN) in their flowers and pitchers, respectively. Recently we demonstrated Nepenthes khasiana EFN as a sugar mix with minimal nitrogenous metabolites and vitamin C. N. khasiana EFN showed insect toxicity due to its strong acetylcholinesterase (AChE) inhibition, and the active principle has been characterized as the naphthoquinone derivative, (+)-isoshinanolone. These findings prompted us to study the chemical composition and toxicity of N. khasiana FN. N. khasiana FN was analyzed for its sugars, amino acids, proteins, fatty acids and vitamin C by HPTLC-densitometry, UFLC, GC-MS and biochemical assays. C:N ratio and naphthoquinones were analyzed by CHNS analyzer, headspace-GC-MS, and GC-FID, respectively. Toxicity of FN and the naphthoquinone droserone, found in its pitcher fluid, was evaluated using the AChE inhibition assay. N. khasiana FN showed a similar chemical pattern as its EFN, viz., sugar (Glc-Fru-Suc)-mix with minimal amino acids, vitamin C, and moderate protein and fatty acid contents. It showed fairly high C:N ratio. The naphthoquinone, plumbagin, was the major volatile constituent in N. khasiana flowers. Crucially, the AChE inhibitors, (+)-isoshinanolone and plumbagin, were absent in N. khasiana FN, which showed no AChE inhibition. Droserone, however, exhibited strong AChE inhibitory activity. The chemical profiles of EFN and FN reflect a nitrogen-limited metabolism in N. khasiana. Notably, the functional allocation of neurotoxic naphthoquinones - abundant in EFN, absent in FN, and present in the pitcher fluid - reflects an adaptive strategy that optimizes both nutritional gain through prey capture and reproductive success through pollination.

This study explores how bioactive compounds in green coffee beans (Coffea arabica L.) vary across different geographic regions, addressing the key question of how environmental factors shape coffee biochemistry and adaptation mechanisms to diverse conditions. Identifying these variations provides insight into how environmental and processing factors influence coffee's sensory quality. Samples from six major coffee-producing regions were analysed for key bioactive compounds, including biogenic amines, caffeine, trigonelline, sucrose, free amino acids, and phenolics. Total polyphenol content and polyamine concentrations were measured, and PCA was used to differentiate samples based on chemical composition. A correlation analysis was specifically conducted for Brazilian samples, using meteorological and environmental data. Total polyphenol content ranged from 44.8 to 70.7 mg GAeq g^-1 FW, with Brazilian samples having the highest levels. Putrescine, the most abundant polyamine, varied significantly (0.02-1.9 μg g^-1 FW). PCA highlighted Ethiopian samples with high sucrose and low caffeine. Brazilian samples showed distinct separation based on key compounds, including putrescine, trigonelline, and amino acids. Environmental factors in Brazil correlated with polyamine and amino acid composition, suggesting associations with heat and drought tolerance. Environmental factors, particularly heat and drought, influence the biochemical profile of coffee beans. Polyamine levels correlate with stress tolerance, while amino acid composition reflects adaptations for osmotic protection. These findings enhance our understanding of coffee's biochemical adaptation to diverse climates and offer valuable insights for optimizing cultivation strategies in the face of climate change.

Trans-acting small interfering RNA (tasiRNAs) are a special type of endogenous small RNAs (sRNAs) found only in plants. Their biogenesis requires an initial miRNA-mediated cleavage of RNA precursors transcribed from TAS genes. TasiRNAs act in trans to silence gene expression by cleaving mRNAs with sequences partially complementary to their own. While Arabidopsis thaliana contains several TAS genes not found in other plants, the miR390-TAS3-ARF pathway is highly conserved among land plant lineages. This pathway exerts its function by silencing a subgroup of Auxin Response Factor (ARF) genes; these tasiRNAs are termed tasiR-ARFs. Many downstream auxin signals are mediated by ARFs acting as transcription factors to confer sensitivity and robustness to the hormone responses in diverse development contexts. These pathway functions are critical for plant growth, developmental timing, and correct organ patterning, such as leaf morphology and polarity, lateral root architecture, and flowering, as well as coping with stress. The phenotypes caused by mutations affecting tasiR-ARF production vary across plant species, showing pleiotropic effects, suggesting a co-opted process where the tasiR-ARF pathway evolution occurred to serve different functions, depending on plant developmental cues. One way to unify the diverse roles of this pathway would be through auxin response integration, possibly by exploring the evolution of ARF3 transcription factors and downstream genes. In this review, we discuss versatility of the tasiR-ARF pathway in land plants according to known developmental and environmental responses where the phytohormone auxin plays an essential role.

The genus Medicago, which includes the widely cultivated forage crop alfalfa, is of significant agricultural and ecological importance. Understanding genetic diversity in Medicago is essential for the conservation of its germplasm and its utilisation in plant breeding. This study aimed to assess the genetic diversity and population structure of the Medicago germplasm collection at the German Federal Ex situ Gene Bank. Genotyping-by-sequencing was used to analyse 1234 accessions of the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), representing 40 Medicago species. After filtering, a high-quality dataset of 23,315 single nucleotide polymorphisms (SNPs) was generated. Our analyses revealed distinct genetic clusters corresponding to Medicago species and sections, with cultivated M. sativa L. and M. × varia Martyn clustering together with less genetic diversity compared to their wild counterparts. This reflects the shared genetic composition and extensive gene flow between M. sativa and M. × varia, commonly considered a hybrid between M. sativa and M. falcata L. Wild species displayed a more complex genetic structure, with polyphyletic patterns indicating higher genetic differentiation that reflects their diverse evolutionary histories and ecological adaptations. In conclusion, the comprehensive diversity analysis of the IPK Medicago collection provides valuable insights for gene bank management, targeted conservation efforts and strategic breeding initiatives.

Calcium ions (Ca²⁺) are essential for plant development and stress responses, including heavy metal (HM) stress. However, the roles and mechanisms of calmodulin proteins (SlCalMs) in mediating cadmium (Cd) stress in Solanum lycopersicum, a model crop, remain poorly understood. This study aimed to investigate the calcium-mediated stress response in S. lycopersicum by identifying and characterizing the SlCalMs gene family, a key subfamily of calcium-binding proteins (CBPs), to elucidate their potential roles in stress tolerance. A genome-wide identification of SlCalMs was conducted using Oryza sativa sequences as a reference. Bioinformatics analyses included BLASTP searches, sequence alignment, phylogenetics, assessment of physicochemical properties, gene structure and motif analysis, chromosomal mapping and duplication events. Gene expression was assessed under Cd stress using RNA-seq and validated by quantitative real-time polymerase chain reaction (qRT-PCR). Molecular docking simulations evaluated Cd-binding affinities, and protein-protein interaction networks, and Gene Ontology (GO) enrichment were used to explore biological functions. Eight distinct SlCalM groups were identified, varying in gene size, exon number and isoelectric point. Conserved motifs, exon-intron patterns and stress-responsive cis-elements were identified. Chromosomal analysis revealed segmental duplications. Under Cd stress, several SlCalMs showed differential expression; notably, Solyc04g077830 was significantly downregulated and showed strong Cd-binding affinity in silico, suggesting a role in Cd sequestration. GO and interaction network analyses confirmed their involvement in Ca²⁺ signalling, metal ion binding and stress-related pathways. This study provides comprehensive insight into the structure, evolution and functional roles of SlCalMs in tomato. Their involvement in Ca²⁺ signalling and Cd stress response highlights their potential for improving HM tolerance, offering valuable targets for future genetic or biotechnological interventions in crop improvement.

Mediterranean temporary ponds (MTPs) are dynamic habitats where low levels of dissolved oxygen can significantly impact plant life. This study investigated the effect of hypoxia and near-anoxia on seed germination and the induction of secondary dormancy in 14 plant species, characteristic of this habitat. Imbibed seeds were subjected to various oxygen concentrations (0.1, 5, 10, or 21% O₂), in both light and darkness. We also tested seed ability to recover germination by moving them to aerobic conditions. We measured embryo growth after hypoxic treatments and during recovery in three species with morpho-physiological dormancy, a rarely investigated response in this dormancy class. Our findings revealed a wide range of species-specific responses. Hypoxia did not inhibit germination in half of the tested species in the light, while near-anoxia completely inhibited germination in all species. However, most seeds fully recovered germination ability once aerobic conditions were restored. Interestingly, hypoxia in darkness reduced or prevented germination in some species and specifically induced secondary dormancy in Juncus bufonius. Surprisingly, seeds of Bulliarda vaillantii lost their light requirement for germination under hypoxia. In three Ranunculus species with morpho-physiological dormancy, hypoxia slowed embryo growth, which delayed germination recovery. This study reveals that MTPs species have evolved adaptations, ranging from tolerance to hypoxic conditions, to the ability to trigger secondary dormancy, which are crucial to surviving and reproducing in these unique environments. The results offer new insights into the germination ecophysiology of MTPs species and their regeneration niche in temporary wetlands.

Soybean (Glycine max), is an important oilseed crop that plays a vital role in ensuring global food security. However, it is susceptible to multiple abiotic stresses that can reduce yield. The ubiquitination-proteasome pathway is a crucial regulatory mechanism that controls a broad range of processes in plants. We investigated the function of Glycine max drought-induced SINA (GmDIS1), an E3 ligase gene, in soybean abiotic stress tolerance using Agrobacterium-mediated transformation to develop soybean GmDIS1-RNAi transgenic lines. GmDIS1 was significantly induced under drought and heat stress. Several physiological traits revealed resilience of GmDIS1-RNAi lines under drought and heat stress. The functions of stress-related genes, such as AOS and GmPAL were investigated to dissect the pathways that contribute to drought and heat tolerance in GmDIS1-RNAi lines. The results suggest that decreasing expression of GmDIS1 can enhance soybean tolerance to drought and heat, and also provide a significant target for developing more drought- and heat-tolerant soybean varieties and other crops.