Annals of botany最新文献

Background and aims: The maintenance of seed banks and timing of germination are fundamental to ensuring population persistence. Physical dormancy (PY) in disturbance-prone environments contributes to these processes via an impermeable seed coat. Dormancy is broken often by heating, which in fire-prone regions is determined by species-specific threshold temperatures. However, the mechanisms by which seeds persist or control dormancy-breaking thresholds in such environments are unclear. We determined whether unsaturated and saturated fatty acids (FAs; within triacylglycerols), common lipids linked to heat-stress resilience, might contribute to seed coat dormancy and overall seed persistence, and whether fire selects for different FA compositions and drives PY function in fire-prone regions.

Methods: We characterized seed FA compositions of 26 Fabaceae species from fire-prone and fire-free ecosystems through gas chromatography-mass spectrometry. We compared FA saturation, total relative FA content and the highest melting point FA of each species across seed tissues (seed coat vs internal tissues) and habitat type (fire-prone vs fire-free) and, for fire-prone species, tested for a relationship with species-specific dormancy-breaking thresholds.

Key results: No relationship between FA composition and species-specific dormancy-breaking thresholds was found. Seeds of fire-free species had more saturated FAs than fire-prone species, particularly for internal tissues. FA saturation was higher in seed coats than in internal tissues across both habitat types. Relative FA content was similar in internal tissues across habitat type but differed for seed coats, with fire-prone species having marginally more FAs.

Conclusions: While no correlation existed between FA composition and dormancy-breaking thresholds in fire-prone species, the consistent differences between seed tissue types we found highlight a similar role for FAs in seed coats across habitats, probably linked to maintaining impermeability. Some evidence supports fire selecting for greater total FA content in seed coats, but further work is needed to test its relationship with temperature thresholds.

Background and aims: Trait-based approaches have advanced our understanding of plant strategies; however, they often focus on leaf-level traits, overlooking the functional roles of stem anatomy and twig characteristics. We investigated intraspecific trait variation in Salix flabellaris, an alpine dwarf shrub, along climatic gradients in the Himalayas. Our goal was to identify distinct axes of trait variation related to stem, twig and leaf traits, assess their environmental drivers and evaluate population-specific growth responses to recent climate change.

Methods: We measured anatomical and morphological traits in stems, twigs and leaves across central and marginal populations along three Himalayan transects. Environmental gradients included variation in growing season temperature and soil moisture. Basal area increment from 2000 to 2021 was analysed to assess long-term growth trends in different areas.

Results: Trait dimensions were largely independent, reflecting distinct ecological strategies: (1) stem anatomical trade-off between hydraulic safety and conductivity; (2) twig dimension balancing construction costs and mechanical strength; and (3) leaf dimension along the exploitative-conservative axis. Higher temperatures enhanced performance, manifested as larger twigs and reduced tissue construction costs, but only in conditions with sufficient soil moisture. Central populations at mid-elevations displayed the favourable trait combinations and highest growth rates. In contrast, marginal populations (higher and lower elevations) showed traits indicating structural reinforcement and conservative resource use. Climate warming over recent decades enhanced stem growth primarily in high-elevation populations, where low-temperature constraints were relaxed.

Conclusions: This study demonstrates that stem, twig and leaf traits represent distinct yet complementary strategies, with environmental filtering shaping their expression along climate gradients. Central populations exhibit the highest growth in current conditions, and climate change is shifting growth advantages towards higher elevations. These findings highlight the need for integrated, multi-organ trait assessments to predict species performance, persistence and potential range shifts under future climatic scenarios.

Background and aims: Automatized species identification tools have massively facilitated plant identification. In mosses, spore ultrastructure appears to be a promising taxonomic character, but has been largely under-exploited. Here, we test artificial intelligence-based approaches to identify species from their spore morphology. In particular, we determine whether the number of spores, their polarity, and variation among populations and capsules affect model accuracy.

Methods: Scanning electron microscopy spore images were generated for five capsules of five populations in ten species. Convolutional neural networks with a highly modularized architecture (ResNeXt) were trained to identify the species, population and capsule of origin of a spore. The training set was progressively sub-sampled to test the impact of sample size on model accuracy. To assess whether variation in spore morphology among populations affected model accuracy, one population was successively removed to test a model trained on the four remaining populations.

Key results: Species were correctly identified at average rates of 92 %, regardless of polarity. Model accuracy decreased progressively with decreasing sample size, dropping to about 80 % with 15 % of the initial dataset. The population and capsule of origin of a spore was retrieved at rates >75 %, indicating the presence of diagnostic population and capsule markers on the sporoderm. Strong population structure in some species caused a substantial drop of model accuracy when model training and testing was performed on different populations.

Conclusions: Spore morphology appears to be an extremely promising tool for moss species identification and may usefully complement the suite of morphological characters used so far in moss taxonomy. The presence of spore diagnostic features at the population and capsule level raises substantial questions on the origin of this structure, which are discussed. Substantial infraspecific variation makes it necessary, however, to train an automatized identification tool from a range of populations and capsules.

Background and aims: Root exudation and rhizodeposition are critical pathways for plant C allocation to soil, influencing soil organic carbon stability and ecosystem functioning under changing climates. However, the effects of drought stress on these belowground processes remain poorly understood. We provide an updated and comprehensive assessment of the current state of knowledge on how drought stress affects root-derived C fluxes (root exudates, rhizodeposition) across diverse functional types and experimental setups to direct future research.

Methods: We conducted a meta-analysis to quantify how drought stress affects total C and other compound classes in root exudation and rhizodeposition.

Key results: Our analysis included 40 data points spanning diverse functional types, ecosystems, sampling methods and experimental conditions. We observed that root-released total C significantly increased in response to drought stress. Among compound classes, carbohydrates and organic acids also increased in response to drought stress, suggesting these compound classes may underlie total C responses in root exudation and rhizodeposition. The variables that explained the most variance in total C response ratio were: ecosystem, flowering type, cotyledon type, functional type, and drought intensity.

Conclusions: To direct future research, our analysis identified knowledge gaps, particularly the need for studies to examine trees and shrubs, field-based research, broader drought intensity ranges, and measurements of total C, compound classes, and specific compounds when possible. Improving our understanding of root-derived C responses to stress is crucial for predicting terrestrial C cycling dynamics and ecosystem function under increased drought frequency and intensity.

Background: Synthetic microbial communities (SynComs) are changing the mechanism of crop protection which ensures global sustainability in agricultural system. This review covers design principles of top-down and bottom-up strategies, demonstrating how strain selection, high-throughput culturing and multi-omics, metabolic modeling, and adaptive evolution can be combined to produce ecological balanced and functional microbial networks. It also describes practical delivery methods like seed coating, foliar sprays, and encapsulated soil amendments that might transfer the precision of the laboratory into real-world agriculture.

Scope: The applicability of this mechanism in crops such as garlic, pakchoi, and cotton illustrate the potential of SynComs to improve uptake of nutrition, trigger plant defense, and improve soil biota to suppress disease. In addition we highlighted on leveraging on high-throughput genome editing such as clustered regularly interspaced short palindromic repeats (CRISPR), artificial intelligence simulation, and molecular screening that are making community engineering and predictive control possible. At the same time, while they offer significant advantages, challenges exist. Achievement will depend on addressing problems of stability, biosafety, and replicability in variable field conditions. Progress toward international coordination, particularly through institutions like the food and agriculture organization and consultative group on international agriculture research, will provide a basis for standards of safety and efficacy for microbial bioformulations.

Conclusion: Conclusively, Synthetic microbial communities are a step in the right direction toward a potentially more resilient form of agriculture; one that synthesizes microbiology and ecology in a unified attempt to restore balance, productivity, and sustainability to farm systems.

Background and aims: Senescence is a final stage of plant development occurring from cells and organs to whole organisms. In clonal herbs, the senescence of a clonal growth organ (e.g. rhizome) causes physical separation of offspring rooting units (ramets) from one genetic individual (genet). Although well-documented in aboveground organs and fine roots, senescence in rhizomes has not been studied, despite its potential implications in clonal multiplication, plant carbon economy, and soil carbon cycles. This study investigates structural and functional changes related to senescence in belowground organs.

Methodology: Twenty clonal fragments of the alpine species Rumex alpinus (7 to 14 years old) were collected at the Krkonoše Mountains, Vrchlabí - Czech Republic. Rhizomes and adventitious roots were subjected to morphological, anatomical, histochemical, and potential hydraulic conductivity analyses.

Key results: As rhizomes age, we observed colour shift from yellowish to dark brown or black, turgor loss and shrinkage in the blackened parts. Anatomical analysis showed progressive deterioration of inner integrity, with increased damage and hollows bordered by wound tissue in older segments. Calcium oxalate crystals in parenchyma cells and vessel elements sealed with phenolic, lipid compounds, and tylosis were more frequent in the middle and old segments compared to the young. The potential hydraulic conductivity of rhizome and roots was assured as it increased towards the oldest parts due to large and more lignified vessels. Abscission zone, like those found in other plant organs, was identified separating the oldest living portion from the decaying part.

Conclusions: Our study is the first to investigate anatomical changes and abscission zone formation during rhizome ageing. Rhizomes thus undergo programmed death, like leaves and fruits. The drivers of programmed death in rhizomes require further studies that may contribute to our understanding of how rhizome longevity influences clonal plant performance and contributes to the plant and soil carbon cycle under varying environmental conditions.

Background and aims: Calotropis procera, a resilient shrub of arid ecosystems, holds considerable potential for domestication, yet its genomic adaptation and climate resilience remain underexplored. This study aims to uncover the genetic variation and environmental adaptability of C. procera across heterogeneous habitats in the Indian Thar Desert, particularly in the context of ongoing climate change.

Methods: To investigate local adaptation, 134 core genotypes from 570 accessions were integrated with environmental data for genotype-environment association analyses. The study employed habitat suitability modeling, genotype-environment association analyses and projected genomic vulnerability under two climate change scenarios (SSP126 and SSP585). Candidate loci from both models were used to compute the adaptive index, Genomic Offset, and RONA across landscape.

Key results: Three genetically distinct clusters were identified, shaped by geographic and climatic factors. A total of 478 significant SNP-environment associations, predominantly linked to temperature and precipitation, revealed multiple genomic signatures contribute to environmental adaptation. Spatial patterns of adaptive potential and vulnerability were mapped. Species distribution modeling projected a decline in suitable habitats by 2081 under SSP585. A significant linear correlation between genomic offset and population suitability was observed under SSP126 (2021, 2081) and SSP585 (2021); however, this relationship was absent under SSP585 (2081), underscoring the potential genetic erosion under more severe climate scenarios.

Conclusion: This study demonstrates spatial variation in the adaptive capacity of C. procera populations, emphasizing the relevance of landscape genomics in assessing climate resilience. This approach is crucial for predicting genetic vulnerability, guiding conservation priorities, and supporting domestication strategies in arid environments under future climate scenarios.

Extrafloral nectaries are defense structures that protect plants against herbivores. In Passiflora, extrafloral nectaries are prominent features, and the YABBY family transcription factor CRABS CLAW (CRC) has been proposed to regulate their development. Here, we investigated the morphoanatomy of petiolar nectaries and characterized the CRC gene at distinct stages of nectary development in Passiflora alata and Passiflora cincinnata. We carried out bioinformatics and phylogenetic analyses, followed by scanning electron microscopy, anatomy, in situ hybridization, and RT-qPCR assessment of nectaries sampled at three leaf developmental stages. The CRC gene was found to contain a highly conserved C2C2 zinc finger motif (composed of three β-sheets and a potential fourth β-sheet or α-helix) and a YABBY domain (two α-helices); along with variable regions. Passiflora-CRC protein sequences clustered closely to Rosids and Asterids. P. cincinnata presented short-patelliform nectaries, whereas those of P. alata were broader and cupuliform. Both species exhibited a similar multiseriate secretory epidermis in the crater region, an underlying nectariferous parenchyma with highly vacuolated, compact cells, and a subnectariferous parenchyma with vascular bundles that terminated before reaching the nectariferous zone. Meristematic activity was pronounced in the early stages and in fully developed nectaries, indicating progressive tissue differentiation. Pa-CRC and Pc-CRC expression peaked during the expanding leaf stage and was limited to the inner regions of the nectary. CRC presented stage-specific expression and conserved structural domains that resembles other species where CRC acts as a key regulator. This suggests a possible correlation between CRC and nectary development.

Background and aims: Natural or anthropogenic disturbances influence aerial biomass and drive distinct resilience strategies in plants. Resprouting ability is considered one of the primary response traits in post-disturbance recovery. The afforestation of many Cerrado ecosystems (the world's most species-rich tropical savanna) generates a change in the environment of native plants. In this study, we investigated the responses of acaulescent palm species to different disturbances in the Brazilian Cerrado and globally. We hypothesised that acaulescent palms share functional traits that support persistence across disturbance regimes, regardless of geographic origin.

Methods: We first investigated the effects of disturbance (biomass removal) on two acaulescent palms from the Cerrado, Allagoptera campestris and Syagrus loefgrenii, subjected to different historical contexts (unaffected, under a pine afforestation, and under a Cerrado regeneration). We assessed and compared above- and belowground traits of plants from areas with different histories. We then assessed the resprouting ability after the removal of the aboveground biomass and compared the number of leaves, plant height and number of ramets to the pre-removal state over one year. To place our findings in a broader context, we compiled a global database of acaulescent palms (APALM) and conducted a meta-analysis of disturbance responses.

Key results: The two target species altered their morphological traits in response to environmental changes caused by long-term pine cultivation. Yet, the target species were able to resprout after the removal of aboveground biomass. Almost 10% of all palm species are acaulescent (geophytes). The meta-analysis showed that disturbances had either positive or non-significant effects on belowground traits across species.

Conclusions: Acaulescent palms are resilient to disturbances. Even when exposed to repeated disturbances, they manage to resprout and recover due to their multiple morphological adaptations. The diversity observed in belowground system architecture, ranging from differences in ramification to shifts in growth habit under varying conditions, illustrates adaptive capacity in disturbance-prone ecosystems.