Leaf Traits Research Articles

Canopy temperatures strongly overestimate leaf thermal safety margins of tropical trees.

Current estimates of temperature effects on plants mostly rely on air temperature, although it can significantly deviate from leaf temperature (Tleaf). To address this, some studies have used canopy temperature (Tcan). However, Tcan fails to capture the fine-scale variation in Tleaf among leaves and species in diverse canopies. We used infrared radiometers to study Tleaf and Tcan and how they deviate from air temperature (ΔTleaf and ΔTcan) in multispecies tropical tree plantations at three sites along an elevation and temperature gradient in Rwanda. Our results showed high Tleaf (up to c. 50°C) and ΔTleaf (on average 8-10°C and up to c.20°C) of sun-exposed leaves during 10:00 h-15:00 h, being close to or exceeding photosynthetic heat tolerance thresholds. These values greatly exceeded simultaneously measured values of Tcan and ΔTcan, respectively, leading to strongly overestimated leaf thermal safety margins if basing those on Tcan data. Stomatal conductance and leaf size affected Tleaf and Tcan in line with their expected influences on leaf energy balance. Our findings highlight the importance of leaf traits for leaf thermoregulation and show that monitoring Tcan is not enough to capture the peak temperatures and heat stress experienced by individual leaves of different species in tropical forest canopies.

Leaf Trait Variability and CSR Strategy Shifts in Mediterranean Woody Species along an Edaphic Gradient

Plant species in Mediterranean ecosystems are expected to exhibit diverse responses to environmental stresses such as climate aridity and challenging soil conditions by adopting various functional strategies. However, intraspecific variability at the local scale has received insufficient attention in the study of CSR strategies. This study aims to evaluate intraspecific variability in leaf traits and CSR strategies of seven woody species growing on ultramafic and non-ultramafic soils in the Beni Bousera region of Northern Morocco. We first conducted a physicochemical analysis to assess differences in soil composition between the two sites. Subsequently, we measured leaf fresh weight, leaf dry weight, and leaf area and calculated CSR strategies for 10 individuals per species. The results revealed significant differences between the two soil types, primarily driven by a moderate serpentine effect characterized by a Ca:Mg ratio <1 in the ultramafic site, along with distinct soil texture. In response to these challenging conditions, we observed substantial intraspecific variability in leaf traits, accompanied by shifts in CSR strategies for certain species. At the ultramafic site, Quercus coccifera adopted an S strategy, while Cistus salviifolius exhibited an S/SC strategy. Lavandula stoechas and Teucrium fruticans displayed notable interindividual variability, whereas Cistus atriplicifolius, Phillyrea latifolia, and Erica arborea maintained consistent strategies across both sites. Our research contributes to the enrichment of CSR databases and highlights the applicability of the CSR strategy framework at the local, intraspecific level, offering a valuable foundation for future ecological studies and plant conservation efforts. Moreover, investigating intraspecific variability in leaf traits and CSR strategies enhances our understanding of plant adaptation mechanisms in extreme environments such as Mediterranean serpentine soils.

Genetic inheritance of leaf and pod traits in blackgram [Vigna mungo (L.) Hepper]

Genetic inheritance of leaf and pod traits in blackgram [Vigna mungo (L.) Hepper]

Correction to: Inter- and intraspecific adaptations of pteridophyte leaf traits in limestone and non-limestone forests of monsoon tropical regions of southwest China

Correction to: Inter- and intraspecific adaptations of pteridophyte leaf traits in limestone and non-limestone forests of monsoon tropical regions of southwest China

Green Synthesis of Zinc and Iron Nanoparticles Using Psidium guajava Leaf Extract Stimulates Cowpea Growth, Yield, and Tolerance to Saline Water Irrigation

Plants use a variety of physiological, biochemical, and molecular mechanisms to mitigate salt stress impacts. Many techniques, including the application of nanoparticles (NPs), are being used to increase plant stress tolerance. To assess the growth and productivity of Vigna unguiculata L. (cowpea) plants exposed to salt stress, cowpea has been cultivated using different saline water levels and subjected to green synthesized zinc NPs (ZnNPs) and iron NPs (FeNPs) applied via foliar spraying. The cowpea plants that grew under the lowest saline water level showed the best leaf traits, leaf water content per area (LWCA), pods, and seed yields, but when salinity levels increased, the plants’ growth and productivity slightly declined. ZnNP and FeNP treatments slow down the degradation of photosynthetic pigments and greatly mitigate the negative effects of salt stress. In both stressed and unstressed plants, ZnNP treatments produced the highest osmoprotectant concentrations (proline, protein, and total carbohydrates). As a result of salt stress, cowpea seeds showed a marked decrease in dry matter and protein content, but ZnNP and FeNP treatments increased it. Conclusively, the results obtained indicated that ZnNPs and FeNPs foliar application to cowpea plants stimulated leaf pigment and polyphenol production, which in turn increased seed dry matter, seed yield, protein content, and the plants’ ability to withstand saline stress.

Comparing Different Methodologies to Quantify Particulate Matter Accumulation on Plant Leaves

Urban air pollution poses a significant threat to human health, with metropolitan areas particularly affected due to high emissions from human activities. Particulate matter (PMx) is among the most harmful pollutants to human health, being composed of a complex mixture of substances related to severe pulmonary conditions. Urban green spaces play a vital role in mitigating air pollution by capturing PMx, and it is essential to select plant species with a high capacity for PMx accumulation to effectively enhance air quality. This study aimed to evaluate and compare the accuracy of two PMx quantification methods—light microscopy and filtration—which demonstrated a high correlation (R2 = 0.72), suggesting that both methods are reliable for assessing PMx accumulation on leaves. Light microscopy allowed for the visualization of PMx deposition, revealing the species warranting further analysis using the filtration method. Among the species analyzed, Euonymus japonicus, Ligustrum lucidum, Alnus glutinosa, Rubus ulmifolius, and Laurus nobilis demonstrated the highest total PMx accumulation, exceeding 50 µg cm−2, making them particularly valuable for air pollution mitigation. This study examined the correlation between leaf traits such as specific leaf area (SLA), leaf area (LA), leaf dissection index (LDI), and leaf roundness and PMx accumulation across the 30 different plant species. A multiple linear regression analysis indicated that these leaf traits significantly influenced PMx accumulation, with SLA and LA showing negative correlations and leaf roundness exhibiting a positive correlation with PMx deposition. In conclusion, this study highlights the importance of selecting plant species with specific leaf traits for effective air quality improvement in urban environments particularly in highly polluted areas, to enhance air quality and public health.

Mycorrhizal inoculation alters rhizosphere fungal community and root morphology to improve drought tolerance of resource-acquisitive but not resource-conservative Quercus species

The mutualistic association between mycorrhizal fungi and plants is well known to improve plant drought resistance. However, the influence of external inoculants on the interactions between soil microbial communities and plant functional traits and how these interactions improve plant drought tolerance under drought stress remain unclear. We conducted a pot inoculation experiment to assess the effect of two inoculated fungal strains (Clitopolius hobsonii NL-19 and C. sp. HSL-YX-7-A) on morphological traits and rhizosphere fungal communities of eight Quercus species seedlings. Plant and soil fungal traits were measured 2 months after inoculation and then underwent a short-term (33 days) drought rewetting treatment. The biomass of all tree species reduced significantly under drought stress followed by rewetting (drought treatment) compared with that in the control treatment (well-watered); however, inoculated mycorrhizal fungi (drought + mycorrhizal inoculation treatment) increased the biomass of five Quercus species (growth-promoting species (GPS) exhibiting a significant increase in biomass under mycorrhizal inoculation treatment than under the uninoculated treatment during drought stress, characterized by a resource-use acquisitive strategy) and had no effect on the other three Quercus species (non-growth-promoting species (NGPS) exhibiting no significant difference in biomass between mycorrhizal inoculation and uninoculated treatments during drought stress, characterized by a resource-use conservative strategy). The leaf traits of the two species groups (GPS and NGPS) varied little among the three treatments. The values of most root traits (e.g., specific root length and root length) of GPS increased significantly under drought and drought + mycorrhizal inoculation treatments compared with those in the control, whereas relatively minor variations were observed in NGPS among the three treatments. The fungal community composition and functional groups (primary trophic modes) in the drought treatment were altered for NGPS but not for GPS; additionally, they changed in the drought + mycorrhizal inoculation treatment for GPS but not for NGPS when compared with those in the drought treatment. Furthermore, the drought tolerance of GPS was improved directly by fungal functional groups (i.e., Pathotroph-Saprotroph- Symbiotrophs proliferation) and indirectly by root traits (e.g., increased specific root length), whereas NGPS may adapt to drought stress through other pathways (e.g., physiological and biochemical regulation). Overall, drought and mycorrhizal inoculation affected the root traits and fungal community structure of Quercus seedlings, which rely on plant resource-use strategies. Our results provide new insights into the relationship between plant resource-use strategies and soil microbes for improving plant performance under drought stress.

Morphological Traits and Biomass Allocation of Leymus secalinus along Habitat Gradient in a Floodplain Wetland of the Heihe River, China

Plant organ biomass allocation and morphological characteristics are important functional traits. The responses of plant root, stem, and leaf traits to heterogeneous habitats in floodplain wetlands are highly important for understanding the ecological adaptation strategies of riparian plants. However, the patterns of these responses remain unclear. In a floodplain wetland in the middle reaches of the Heihe River, we studied the responses of the root, stem, and leaf morphological traits and biomass allocation of Leymus secalinus to varying habitat conditions. We measured these traits in three sample plots, delineated based on distance from the riverbank: plot I (near the riparian zone, 50–150 m from the riverbank), plot II (middle riparian zone, 200–300 m from the riverbank), and plot III (far riparian zone, 350–450 m from the riverbank). The results showed that in plot I, L. secalinus tended to have slender roots and stems and small leaves, with a biomass allocation strategy that maximized the root–shoot ratio (RSR). In plot II, L. secalinus had thick stems and moderate leaf and root patterns, and the RSR values were between those of plot I and plot III. In plot III, L. secalinus had thin and short stems and large leaves; furthermore, among the root morphological structures, plot III had the shortest Rhizome length (RL) and longest Rhizome diameter (RD), and the RSR was the lowest. Moreover, there was a significant correlation between organ biomass and leaf thickness, stem length, RD, and RL in the three habitats (p < 0.05). By balancing the biomass allocation among organs, wetland plants in floodplains balance changes in root, stem, and leaf morphological characteristics to improve their environmental adaptation.

Specific leaf area and its within-individual variation in understory evergreen and deciduous woody species in New Zealand

Specific leaf area (SLA) plays a critical role in carbon assimilation and nutrient cycling. While leaf habit (deciduous vs. evergreen) has often been recognized as a reliable predictor of SLA—with deciduous species typically having higher mean SLA values due to lower concentration of structural components compared to evergreens—high variation in SLA among evergreen species suggests further investigation of variation for species with this leaf habit could improve predictions of SLA effects on community and ecosystem processes. Furthermore, the presence of leaves of different ages in evergreen plants, emerging over multiple years, could amplify the within-individual variation in SLA, which remains underexplored. Here we report variations of SLA measured from c. 2000 leaves collected from 36 individuals across 19 woody species in an understory environment in New Zealand (NZ). We found that while most deciduous species, predominantly non-native, clustered towards higher SLA values, evergreen species presented a wide SLA spectrum. Moreover, we found that while being deciduous, having a smaller leaf size, and younger leaves, collected from lateral branches, correlated with elevated SLA values, the leaf habit did not primarily drive the within-individual SLA variation. Instead, smaller leaf size emerged as a significant predictor of within-individual SLA variation. The branch-order effect on SLA underscores a methodological consideration: accurate estimation of total leaf area in evergreen trees requires representative sampling across all branch orders. Our study also highlights the need for integrating leaf traits such as leaf size and branch order into functional trait analyses. Further research is vital to understand the underlying mechanisms of these trait variations and their impacts on ecosystem functioning.

Leaf trait networks shift toward high modularity during the succession of a subtropical forest, in southwest China

During the process of forest succession, coexisting plant species fulfill diverse functions by modifying the interrelationships among functional traits. Examining the interrelationships of functional traits across multiple dimensions would enable a comprehensive understanding of the plants’ adaptive strategies during forest succession. Plant trait networks (PTNs) comprehensively capture and visualize these intricate relationships among functional traits. Nonetheless, the changes in PTNs during forest secondary succession remain unclear. In this study, we measured 24 functional traits related to leaf resource acquisition, photosynthesis, hydraulics, and physical defense across tree species at three successional stages: young forest (YF), intermediate forest (IF), and old-growth forest (OF) in the Ailao Mountains, Southwest China. We established leaf trait networks (LTNs) to investigate the interrelationships among functional traits during forest succession. Our results revealed a decrease in the Edge Density decreased and an increase in the Modularity as succession advanced. In the YF stage, leaf nitrogen, photosynthetic rate, and force to punch were the hub traits; whereas, canopy exposure and leaf dry mass were highly connected traits in the IF and OF stages, respectively. The connectivity of highly connected traits was related to the plant’s life-history strategies and environmental adaptations at different successional stages. In terms of the importance of the four trait dimensions, resource acquisition and photosynthetic traits consistently demonstrated strong connectivity within LTNs throughout the succession. We concluded that co-occurring tree species adapted to the changing environmental conditions by adjusting trait modules through alternative strategies during secondary succession. Specifically, resource acquisition and trait coordination were more advantageous in the YF stage, while higher modularity offered greater opportunities for niche differentiation in the OF stage. This study provides new insights into exploring the mechanisms of forest succession through the analysis of trait correlation networks.

Plant economics spectrum governs leaf nitrogen and phosphorus resorption in subtropical transitional forests

BackgroundLeaf nitrogen (N) and phosphorus (P) resorption is a fundamental adaptation strategy for plant nutrient conservation. However, the relative roles that environmental factors and plant functional traits play in regulating N and P resorption remain largely unclear, and little is known about the underlying mechanism of plant functional traits affecting nutrient resorption. Here, we measured leaf N and P resorption and 13 plant functional traits of leaf, petiole, and twig for 101 representative broad-leaved tree species in our target subtropical transitional forests. We integrated these multiple functional traits into the plant economics spectrum (PES). We further explored whether and how elevation-related environmental factors and these functional traits collectively control leaf N and P resorption.ResultsWe found that deciduous and evergreen trees exhibited highly diversified PES strategies, tending to be acquisitive and conservative, respectively. The effects of PES, rather than of environmental factors, dominated leaf N and P resorption patterns along the elevational gradient. Specifically, the photosynthesis and nutrient recourse utilization axis positively affected N and P resorption for both deciduous and evergreen trees, whereas the structural and functional investment axis positively affected leaf N and P resorption for evergreen species only. Specific leaf area and green leaf nutrient concentrations were the most influential traits driving leaf N and P resorption.ConclusionsOur study simultaneously elucidated the relative contributions of environmental factors and plant functional traits to leaf N and P resorption by including more representative tree species than previous studies, expanding our understanding beyond the relatively well-studied tropical and temperate forests. We highlight that prioritizing the fundamental role of traits related to leaf resource capture and defense contributes to the monitoring and modeling of leaf nutrient resorption. Therefore, we need to integrate PES effects on leaf nutrient resorption into the current nutrient cycling model framework to better advance our general understanding of the consequences of shifting tree species composition for nutrient cycles across diverse forests.

Diversity-enhanced canopy space occupation and leaf functional diversity jointly promote overyielding in tropical tree communities

Understanding the mechanisms that drive biodiversity-productivity relationships is critical for guiding forest restoration. Although complementarity among trees in the canopy space has been suggested as a key mechanism for greater productivity in mixed-species tree communities, empirical evidence remains limited. Here, we used data from a tropical tree diversity experiment to disentangle the effects of tree species richness and community functional characteristics (community-weighted mean and functional diversity of leaf traits) on canopy space filling, and how these effects are related to overyielding. We found that canopy space filling was largely explained by species identity effects rather than tree diversity effects. Communities with a high abundance of species with a conservative resource-use strategy were those with most densely packed canopies. Across monocultures and mixtures, a higher canopy space filling translated into an enhanced wood productivity. Importantly, most communities (83 %) produced more wood volume than the average of their constituent species in monoculture (i.e. most communities overyielded). Our results show that overyielding increased with leaf functional diversity and positive net biodiversity effects on canopy space filling, which mainly arose due to a high taxonomic diversity. These findings suggest that both taxonomic diversity-enhanced canopy space filling and canopy leaf diversity are important drivers for overyielding in mixed-species forests. Consequently, restoration initiatives should promote stands with functionally diverse canopies by selecting tree species with large interspecific differences in leaf nutrition, as well as leaf and branch morphology to optimize carbon capture in young forest stands.

3D Morphological Feature Quantification and Analysis of Corn Leaves.

Marked variations in the 3-dimensional (3D) shape of corn leaves can be discerned as a function of various influences, including genetics, environmental factors, and the management of cultivation processes. However, the causes of these variations remain unclear, primarily due to the absence of quantitative methods to describe the 3D spatial morphology of leaves. To address this issue, this study acquired 3D digitized data of ear-position leaves from 478 corn inbred lines during the grain-filling stage. We propose quantitative calculation methods for 13 3D leaf shape features, such as the leaf length, 3D leaf area, leaf inclination angle, blade-included angle, blade self-twisting, blade planarity, and margin amplitude. Correlation analysis, cluster analysis, and heritability analysis were conducted among the 13 leaf traits. Leaf morphology differences among subpopulations of the inbred lines were also analyzed. The results revealed that the 3D leaf traits are capable of revealing the morphological differences among different leaf surfaces, and the genetic analysis revealed that 84.62% of the 3D phenotypic traits of ear-position leaves had a heritability greater than 0.3. However, the majority of 3D leaf shape traits were strongly affected by environmental conditions. Overall, this study quantitatively investigated 3D leaf shape in corn, providing a reliable basis for further research on the genetic regulation of corn leaf morphology and advancing the understanding of the complex interplay among crop genetics, phenotypes, and the environment.

Unfolding the leaf economics spectrum for wheat: Trait analysis and genomic associations across cultivars

The leaf economics spectrum (LES) is an ecophysiological concept that describes the trade-offs between leaf structural and physiological traits. It has been extensively studied across various scales. However, the coordination hypothesis has rarely been tested at the intraspecific scale, especially in crops, for understanding yield increases or predicting evolutionary trajectories. Here, we first tested the relationships among leaf traits and examined the genetic coordination among 209 wheat genotypes. Compared to non-crop grass species, wheat is a fast-growing species, and tends to have a higher value of photosynthetic rate, leaf nitrogen concentration and leaf respiration rate at a given leaf mass per area, although it does align with the predicted direction of the “fast-slow” spectrum. We conducted a principal component analysis (PCA) to compare different traits within wheat. The first axis from PCA (ranging from slow to fast of plant economic investment) is significantly positively associated with the agronomic traits, especially grain yield (R2=0.11, P<0.001). Partially independent changes in leaf nitrogen content and leaf mass per area may allow crops to maximize photosynthetic rates without sacrificing leaf lifespan. The results reveal that some loci are simultaneously associated with different traits, which may be the genetic basis for the formation of trait-trait relationships. The current study deepens the understanding of LES traits in wheat at the intraspecific and genetic levels, supporting the trait-based adaptation strategies to improve wheat productivity and resource-use efficiency.

Plant traits mediate foliar uptake of deposited nitrogen by mature woody plants.

Increased atmospheric nitrogen (N) deposition significantly disturbs ecosystem N cycle. Although foliar interception and uptake of N deposition can provide an important alternative N supply to forest ecosystems, the mechanisms regulating foliar N uptake from wet deposition are not fully understood. Here, we selected 19 woody species with a wide range of plant traits from different functional groups and conducted a 15N isotope labelling experiment through brushing 15NH4 + and 15NO3 - solution on canopy leaves. Our findings demonstrate that leaves can directly absorb N from wet deposition within a few hours. The average leaf 15N recoveries were 10% and 28% under 15NH4 + and 15NO3 - treatments across species, respectively, while twig N recoveries were only 1%-7% of leaf N recoveries. Differences in foliar N uptake efficiency among species were closely associated with leaf traits but were little influenced by meteorological conditions or soil nutrient status. Specifically, plants with higher leaf N concentration, larger specific leaf area and lower wax concentration exhibited higher leaf N recovery. Our results indicated that tree canopies could directly absorb N from atmospheric deposition. We highlight the critical role of leaf traits in determining canopy foliar N uptake, which may consequently influence plant competition under elevated N deposition.

Variation in Phenology and Morphological Traits of Seed-Propagated Laggera alata and Laggera crispata Forms

The phenological and morphological variation studies among forms of Laggera Sch. Bip. Ex. Benth. and Hook species are limited, despite the medicinal use of the genus. Therefore, this study aimed to document phenology and morphological variation in cultivated populations of Laggera alata and Laggera crispata forms from seedling to maturity. The forms were categorized as Laggera alata with a small capitulum (LA-SC), Laggera alata with a large capitulum (LA-BC), Laggera crispata from South Africa (LC-SA), and Laggera crispata from Zimbabwe (LC-ZIM). Seeds were germinated in Petri dishes, transplanted to plug trays, and later to field plots at 60 days. Phenological events were recorded when observed in at least one plant. Twelve qualitative and four morphometric traits were measured monthly on five plants per Laggera form. Analysis of variance and Tukey’s Honestly Significant Difference test (p &lt; 0.05) were used for data analysis. Results indicated significant variation in phenology, qualitative traits, leaf traits, plant height, and stem diameter both within and between L. crispata and L. alata forms. Morphometric traits, such as leaf size and the number of leaves per plant, were identified as key descriptors for differentiating L. alata forms. These findings provide a foundation for the introduction of Laggera forms into farming systems for medicinal and commercial purposes.

The introgression of BjMYB113 from Brassica juncea leads to purple leaf trait in Brassica napus

The purple leaves of Brassica napus are abundant in anthocyanins, which are renowned for their role in conferring distinct colors, stress tolerance, and health benefits, however the genetic basis of this trait in B. napus remains largely unelucidated. Herein, the purple leaf B. napus (PL) exhibited purple pigments in the upper epidermis and a substantial increase in anthocyanin accumulation, particularly of cyanidin, compared to green leaf B. napus (GL). The genetic control of the purple leaf trait was attributed to a semi-dominant gene, pl, which was mapped to the end of chromosome A03. However, sequencing of the fragments amplified by the markers linked to pl indicated that they were all mapped to chromosome B05 from B. juncea. Within this B05 chromosomal segment, the BjMYB113 gene-specific marker showed perfect co-segregation with the purple leaf trait in the F2 population, suggesting that the BjMYB113 introgression from B. juncea was the candidate gene for the purple leaf trait in B. napus. To further verify the function of candidate gene, CRISPR/Cas9 was performed to knock out the BjMYB113 gene in PL. The three myb113 mutants exhibited evident green leaf phenotype, absence of purple pigments in the adaxial epidermis, and a significantly reduced accumulation of anthocyanin compared to PL. Additionally, the genes involved in positive regulatory (TT8), late anthocyanin biosynthesis (DFR, ANS, UFGT), as well as transport genes (TT19) were significantly suppressed in the myb113 mutants, further confirming that BjMYB113 was response for the anthocyanin accumulation in purple leaf B. napus. This study contributes to an advanced understanding of the regulation mechanism of anthocyanin accumulation in B. napus.

Leaf functional traits of Parrotia subaequalis from different environments in eastern China.

Functional traits are important in understanding how plants respond and adapt to their immediate environment. Parrotia subaequalis is a highly endangered arbor species found throughout eastern China, primarily inhabiting hillsides and valleys, yet, little is known about the variation in leaf traits across these environments. In the present study, we tested this by comparing leaf surface area, leaf weight, leaf length, leaf symmetry and leaf mass per unit area, as well as the relationship between leaf traits and environmental factors and the scaling relationship between leaf surface area versus leaf dry mass. We observed significant differences in leaf surface area, weight, and length among the population sites, and these variables were strongly affected by environmental factors, especially high mean annual temperatures in hillside habitats and high mean annual precipitation in valley habitats. The scaling exponents remained numerically variant among the 10 populations, with different slopes greater than 1.0, and the scaling exponents increased significantly with hillside habitats. These metrics correlated with soil thickness associated with different habitat types. The areal ratio (AR) values in all populations deviated from 1, indicating that the two lamina sides were asymmetrical. The standardized symmetry index (SI) values displayed significant variation, especially in leaves from hillside habitats with a high degree of asymmetry. Collectively, our findings demonstrated that leaf functional traits exhibit considerable variability in response to different environmental contexts and provide valuable reference data that could be useful for conserving this endangered species.

Integrative analysis of transcriptome and metabolome provides insights into the mechanisms of leaf variegation in Heliopsis helianthoides

BackgroundIn the field of ornamental horticulture, phenotypic mutations, particularly in leaf color, are of great interest due to their potential in developing new plant varieties. The introduction of variegated leaf traits in plants like Heliopsis helianthoides, a perennial herbaceous species with ecological adaptability, provides a rich resource for molecular breeding and research on pigment metabolism and photosynthesis. We aimed to explore the mechanism of leaf variegation of Heliopsis helianthoides (using HY2021F1-0915 variegated mutant named HY, and green-leaf control check named CK in 2020 April, May and June) by analyzing the transcriptome and metabolome.ResultsLeaf color and physiological parameters were found to be significantly different between HY and CK types. Chlorophyll content of HY was lower than that of CK samples. Combined with the result of Weighted Gene Co-expression Network Analysis (WGCNA), 26 consistently downregulated differentially expressed genes (DEGs) were screened in HY compared to CK subtypes. Among the DEGs, 9 genes were verified to be downregulated in HY than CK by qRT-PCR. The reduction of chlorophyll content in HY might be due to the downregulation of FSD2. Low expression level of PFE2, annotated as ferritin-4, might also contribute to the interveinal chlorosis of HY. Based on metabolome data, differential metabolites (DEMs) between HY and CK samples were significantly enriched on ABC transporters in three months. By integrating DEGs and DEMs, they were enriched on carotenoids pathway. Downregulation of four carotenoid pigments might be one of the reasons for HY’s light color.ConclusionFSD2 and PFE2 (ferritin-4) were identified as key genes which likely contribute to the reduced chlorophyll content and interveinal chlorosis observed in HY. The differential metabolites were significantly enriched in ABC transporters. Carotenoid biosynthesis pathway was highlighted with decreased pigments in HY individuals. These findings not only enhance our understanding of leaf variegation mechanisms but also offer valuable insights for future plant breeding strategies aimed at preserving and enhancing variegated-leaf traits in ornamental plants.

Phenotypic plasticity as the main driver of alien plant trait variation in urban versus rural microclimate for the model species Veronica persica.

Urban environments are warmer than the rural surroundings, impacting plant phenotypic traits. When plants are present over areas with contrasted conditions such as along urbanization gradients, their phenotypes may differ, and these differencesdepend on different processes, including phenotypic plasticity, maternal environmental effects and genetic differentiation (local adaptation and/or genetic drift). Successful establishment of alien species along environmental gradients has been linked to high phenotypic plasticity and rapid evolutionary responses, which are easier to track for species with a known residence time. The mechanisms explaining trait variation in plants in urban versus rural microclimatic conditions have received little attention. Using the alien Veronica persica as model species, we measured leaf traits in urban and rural populations and performed a reciprocal common-garden experiment to study how germination, leaf, growth, and flowering traits varied in response to experimental microclimate (rural or urban) and population origin environment (rural or urban). Veronica persica displayed phenotypic plasticity in all measured traits, with reduced germination, development, and flowering under urban microclimate which suggests more stressful growing conditions in the urban than in the rural microclimate. No significant effect of the rural or urban origin environment was detected, providing no evidence for local adaptation to urban or rural environments. Additionally, we found limited signs of maternal environmental effects. We noted the importance of the mother plant and the population identities suggesting genetically based differences. Our results indicate that urban environments are more hostile than rural ones, and that V. persica does not show any adaptation to urban environments despite genetic differences between populations.