Plant Biology最新文献

The freezing-induced formation of embolisms in xylem conduits presents one of the challenges faced by evergreen leaves in frost-experiencing regions. Given that the probability of permanent embolism formation is related to the conduit diameter, we hypothesized that diameters of the vessels in evergreen leaves should be smaller than in deciduous leaves. We used live botanical garden collections to sample leaves of 21 evergreen and 47 deciduous species originating from various temperate biotopes and representing a broad taxonomic diversity. We determined the diameters of the largest vessels in their petioles. After controlling for conductive path length, the vessels in evergreen leaves were significantly smaller than those in deciduous leaves. Our results suggest a selective advantage of vessel diameter reduction for the evergreen leaf habit in cold climates. This result recapitulates the contrast between deciduous and evergreen species previously reported for stems. Moreover, the strong scaling relationships of vessel diameter with distance to leaf tip found in both leaf forms suggest that evolutionary reduction in vessel diameter associated with the evergreen habit may necessitate leaf size reduction, consistent with the trend documented in other studies.

The cultivated potato Solanum tuberosum subsp. tuberosum L. retains an important reservoir of genetic diversity in its secondary gene pool. More than 100 wild species of potato, with ploidies from 2x to 6x, grow in the Americas. These species are adapted to contrasting environments, showing wide phenotypic diversity in leaf, floral, and tuber morphology. The taxonomic relationship among species is not clear, mainly due to little chromosomal differentiation and pervasive interspecific hybridization. This review summarizes data from more than 20 years of studies on genetic and epigenetic variability of potato species, highlighting the importance of epigenetic variability, hybridization, and polyploidization in the evolution and diversification of this group. The epigenetic diversity of these species remains poorly characterized. This review addresses the ecological implications of epigenetic variation, emphasizing its role in plant adaptation to changing environments. Finally, the study proposes a model that integrates epigenetic variability into the evolution of natural potato populations, highlighting its potential for rapid adaptation and phenotypic differentiation.

The frequencies of droughts worldwide will increase in the future due to climate changes. Nectar composition of plant species varies in relation to pollinator and can also be influenced by drought. We investigated both different pollinated species and the effects of drought in parallel. In addition, the influence of drought on nectar production and metabolism in nectaries should be investigated, since very little is currently known about this. The influence of drought stress on nectaries, nectar and leaves of 4 day- and night-flowering Nicotiana species (pollinated by sunbirds, hummingbirds, hawkmoths or bats) were investigated. The nectar volume, as well as metabolite concentrations (sugars, amino acids), inorganic ions and starch were measured. PCA and PERMANOVA were applied to determine the relative importance of different drought conditions on metabolism of nectaries and nectar. Drought stress led to changes in composition of nectaries and nectar in all four Nicotiana species. The day-flowering species had relatively similar changes, whereas the night-flowering species differed from these and also from each other. Quantities of sugars, amino acids and inorganic ions per flower decreased sharply in all Nicotiana species because of a strong decrease in nectar volume. Drought stress not only compromises plant growth but also nectar secretion and composition. These changes are likely to affect plant-pollinator interactions and may negatively impact successful pollination.

Plants store nutrients, including the micronutrient iron, in bioavailable forms to support growth in subsequent seasons. The perennial lifestyle is preponderant in nature. Arabis alpina is a perennial model organism with a particular architecture of branches having proximal perennial (PZ) and distal annual (AZ) stem zones with distinct anatomy and physiology. PZ undergoes secondary growth and stores carbon-rich macromolecules. Here, we investigated iron homeostasis in PZ versus AZ. We localized iron in stem internodes of PZ and AZ using Perls staining and ferritin immunodetection in the wild-type Pajares (Paj) and perpetual flowering 1 mutant. We mined transcriptome data of the developing PZ and AZ. Iron accumulated at various development stages in PZ and AZ. Iron levels in PZ were ca. two-fold higher than in AZ, irrespective of flowering. Iron was predominantly located within plastid-bound ferritin. Gene expression patterns supported the significance of ferritin and demonstrated enrichment of transcripts related to iron homeostasis within stems. Distinct patterns of expression among iron homeostasis genes were observed in relation to iron content in PZ and AZ, indicating tissue-specific regulatory mechanisms governing iron accumulation. Secondary growth in PZ plays a role in iron storage in the perennial A. alpina, while AZ may transiently store iron for seed production. Future research will address different iron homeostasis signalling pathways in AZ and PZ.

The genus Salvia, comprising around 1000 species, half of which are found in the New World, belongs to the taxonomically most challenging genera within the Lamiaceae. A part of this diversity can be ascribed to the shape and expansion of the corolla and stamen structures, because changes in geometry of the sexual organs and attractance of pollinators might establish propagation barriers. However, the structural, functional, and evolutionary context of the underlying genes has not yet been elaborated. In this study, we analyse a large set of flowers from Salvia species of different geographic origin and use this morphometric framework to address gene expression and phylogenetic analysis of the MADS-box B-class gene, GLOBOSA. We examined expression of GLOBOSA in petals and anthers throughout anthesis for both Salvia pratensis L., as species from Europe, and the American Salvia elegans Vahl. Structural analysis of the B-class genes reveals typical MADS-MIKC-type composition. When we infer phylogenies for GLOBOSA and its binding partner DEFICIENS, we see a genus-wide duplication of DEFICIENS in Salvia and a specific duplication of GLOBOSA in Salvia species from the New World. Based on the first description of flowering genes in the genus Salvia, we arrive at a working model, where a duplication of GLOBOSA enabled the intense radiation of New World Salvia by neo-functionalization of a flower identity gene for morphogenetic control of corolla and anther geometry. We propose that the genus Salvia can be used as paradigm to address the role of EvoDevo for plant speciation.

The iso- to anisohydric continuum describes how plant regulate water potential and has been used to classify species hydraulic strategies. The slow to fast continuum is a whole-plant strategy for resource acquisition and utilization. The relationship between hydraulic and whole-plant economic strategy could provide a comprehensive method for assessing plants performance. We quantified the degree of isohydricity of 20 woody species in a warm temperate forest. We also measured other functional traits associated with hydraulic and economic strategies (leaf gas exchange, pressure-volume traits, predawn and midday water potential, native and maximum stem hydraulic conductivity, Huber value, and wood density), then explored the underlying trade-offs. Pearson correlations and PCA were performed to assess relationships between isohydricity and other functional traits. We found a coordinated series of iso- anisohydric and slow-fast spectra, where species percentage loss of hydraulic conductivity (PLC) and wood density (WD) were the two most powerful proxies. Along the coordinated continuum, the anisohydric species had higher leaf gas exchange, PLC, and water potential at the turgor loss point, and lower WD than the isohydrics. We found that isohydric species have high drought tolerance, giving them a greater chance of survival than the anisohydric species as drought events are anticipated to be more frequent and severe under global climate change. Identification of associated spectra among plant ecological strategies may increase understanding of how woody plants in temperate forests will respond to climate changes.

Phenolic compounds are key to plant defence, offering protection as antioxidants, UV shields, and antimicrobials. Their production is largely shaped by environmental conditions. It is believed that plants at lower elevations increase phenolic content to counter herbivory, while those at higher elevations rely on phenolics to manage abiotic stresses, such as climate variability. Microhabitat warming also affects phenolic levels, but responses differ, depending on broader climatic contexts: plants in warmer, lower-elevation environments show limited adaptability, whereas high-elevation plants demonstrate greater plasticity. Despite the importance of these environmental interactions, many small-scale abiotic studies lack sufficient spatial replication across broader gradients like elevation or latitude, while large-scale studies frequently overlook microscale factors. This study investigated the effects of macroclimate factors and microhabitat warming on phenolic production in Nardus stricta across five semi-natural grassland sites (1546-1875 m a.s.l.) in Portugal's Serra da Estrela. Warming was simulated using open-top chambers over two growing seasons, after which leaf samples were analysed for phenolic compounds, and soil nutrients were measured. The N. stricta plants at the highest elevation site contained significantly higher leaf flavonoid concentrations. Microhabitat warming led to a significant decrease in flavonoid concentrations, but only at the highest elevation site. These effects occurred independently of soil nutrient levels, suggesting direct thermal effects or stress responses might be involved. Our findings highlight the complex interactions between macro- and microenvironmental factors in shaping plant chemistry, underscoring critical considerations for plant resilience in the face of climate change. This understanding is essential for developing strategies to support plant and ecosystem adaptation to changing climates.

Plants invest a substantial fraction of their resources into defence against herbivores, with the highest levels of defence often allocated only to the most valuable tissues. Plants in the genus Erysimum (Brassicaceae) have evolved the ability to produce novel cardenolides, in addition to ancestrally conserved glucosinolates. While these plants co-express both defences, differences in tissue-specific expression might represent an effective cost-saving strategy. Larvae of the glucosinolate-resistant diamondback moth Plutella xylostella occasionally feed on Erysimum cheiranthoides but tend to avoid younger leaves. Here, we predict that caterpillar feeding preference is shaped by variations in cardenolide levels. Thus, we quantified within-plant variations in defence and nutritional traits of vegetative or early reproductive plants and performed feeding assays to evaluate the relative importance of cardenolides. In accordance with optimal defence theory (ODT), the youngest leaves contained the most nutrients and had highest levels of cardenolides, glucosinolates and trichomes, with more extreme within-plant differences found in reproductive plants. Caterpillars consistently avoided the well-defended youngest leaves, both on whole plants and detached leaf discs. Surprisingly, neither experimental addition (external application) nor removal (CRISPR-Cas9 knockout) of cardenolides significantly affected caterpillar feeding preference. Physical and chemical defences, including cardenolides, co-vary within E. cheiranthoides to maximize defence of youngest leaves. While P. xylostella clearly responds to some of these traits, the prominent cardenolide defence appears to lack potency against this specialist herbivore. Nonetheless, the careful regulation and re-mobilization of cardenolides to younger leaves during plant development suggests an important role in plant functioning.

Tan Spot disease is caused by the necrotrophic pathogen Pyrenophora tritici-repentis (Ptr) and poses a significant threat to global wheat production. Therefore, novel sources of resistance need to be identified, coupled with a fuller mechanistic understanding of host responses to Ptr. Herein, we characterise the interaction between a ToxA-positive Ptr strain and parental wheat lines from a multiparent advanced generation intercross (MAGIC) population. Genotypes displaying moderate resistance ('Robigus') or susceptibility ('Hereward') to Ptr challenge were identified and characterised through histological, metabolomic, and transcriptomic approaches. Histological investigations indicated the prominence of papilla-based defences in Robigus. Transcriptomic analyses could link this to the expression of barrier-related genes i.e. actin polymerisation, callose deposition, vesicle trafficking, and cellulose synthesis. Inhibiting actin polymerisation with cytochalasin E increased lesion numbers but did not augment lesion growth, suggesting the deployment of other defence mechanisms. These may be influenced by auxin, as its exogenous application exacerbated symptom development. Transcriptomic and metabolomic analyses in Hereward following challenge with Ptr suggested shifts in primary metabolism, affecting glycolysis, the TCA cycle, and the γ-aminobutyric acid (GABA) shunt. Activation of salicylic acid (SA)-associated genes, including NPR1 and WRKY33, was specific to Hereward, and exogenous SA increased susceptibility to Ptr in both genotypes. This study suggests barrier defences could be effective against Ptr as well as a lack of susceptibility factors like SA or the appropriate processing of IAA. These findings offer potential avenues for enhancing wheat resistance to Ptr.