Multiple Plant Species Research Articles

Fusion of AI Techniques: A Hybrid Approach for Precise Plant Leaf Disease Classification

Classification of plant leaf diseases is an important step in protecting the world's food supply and agricultural yields. There has been encouraging progress in improving the efficiency and accuracy of plant leaf disease diagnosis via the combination of deep learning methods with artificial intelligence (AI) in recent years. This research introduces a new hybrid strategy, CNN+SVM and CNN+RF, that uses deep learning techniques like Convolutional Neural Networks (CNN) in conjunction with more traditional machine learning algorithms like Random Forest (RF) and Support Vector Machine (SVM). Moreover, two hybrid variants, CNN + RF and CNN + SVM, are proposed to exploit the strengths of both paradigms synergistically. To further improve classification accuracy, the study employs Particle Swarm Optimization (PSO) as a feature selection technique. PSO optimizes the feature subset for each classification model, facilitating the extraction of the most informative features, which leads to better discrimination between healthy and diseased plants. The dataset used for experimentation consists of a comprehensive collection of plant leaf images representing various diseases across multiple plant species. Experimental results demonstrate the efficacy of the proposed hybrid approach compared to individual classification methods. The hybrid models achieve higher accuracy rates and improved generalization performance, showcasing the synergistic benefits of combining AI and deep learning techniques. Furthermore, the feature selection process through PSO contributes significantly to enhancing the classification outcomes, providing insights into the discriminative power of selected features. This research contributes to the advancement of plant leaf disease classification methodologies by offering an innovative hybrid approach that leverages the complementary strengths of AI, deep learning, and feature selection techniques. The study's findings underscore the potential for improving plant leaf disease management strategies, ultimately leading to enhanced crop productivity and sustainable agriculture. The proposed hybrid framework can serve as a blueprint for similar classification tasks in other domains, demonstrating the broader impact of synergizing different AI techniques for improved accuracy and performance. CNN+RF gives 95% accuracy, 93% precision, 96% recall and 94% F1 score, whereas CNN+SVM gives 93% accuracy, 91% precision, 94% recall and 92% F1 score.

Alternative pathways leading to ascorbate biosynthesis in plants: lessons from the last 25 years.

l-Ascorbic acid (AsA) is an antioxidant with important roles in plant stress physiology, growth, and development. AsA also plays an essential role in human health, preventing scurvy. Humans do not synthesize AsA, which needs to be supplied via a diet rich in fresh produce. Research efforts have provided progress in the elucidation of a complex metabolic network with at least four routes leading to AsA formation in plants. In this review, three alternative pathways, namely the d-galacturonate, the l-gulose, and the myo-inositol pathways, are presented with the supporting evidence of their operation in multiple plant species. We critically discuss feeding studies using precursors and their conversion to AsA in plant organs, and research where the expression of key genes encoding enzymes involved in the alternative pathways showed >100% AsA content increase in the transgenics and in many cases accompanied by enhanced tolerance to multiple stresses. We propose that the alternative pathways are vital in AsA production in response to stressful conditions and to compensate in cases where the flux through the d-mannose/l-galactose pathway is reduced. The genes and enzymes that have been characterized so far in these alternative pathways represent important tools that are being used to develop more climate-tolerant crops.

Air pollution biomonitoring in an urban-industrial setting (Taranto, Italy) using Mediterranean plant species

This study presents the first report on the elemental composition of five Mediterranean plant species (Pinus pinaster, Eucalyptus camaldulensis, Nerium oleander, Olea europaea and Pittosporum heterophyllum) to trace industrial emissions in Taranto, Italy, a mixed-use industrial and urban setting. Potential metal sources include vehicular traffic, steel and cement plants, and a petrochemical refinery. Samples were collected from 29 sites covering the Tamburi-Lido Azzurro neighbourhood and the historical quarter Città Vecchia-Borgo. High concentrations of toxic metals were observed in all samples, with marked inter-species variability. Model based clustering identified two distinct groups, one dominated by pine needles with higher metal concentrations than the other group composed of the other four plant species. The contamination factor (CF) and pollution load index (PLI) indices which use background samples to standardise the level of pollution, were used to remove species effect allowing for direct site comparison. Spatial analysis of CF and PLI data identified pollution hotspots near industrial areas and major roads, with areas of little to no air pollution near green spaces. Statistical analysis of the CFs revealed the contribution of different sources to element emissions. Ni and Cr were primarily emitted from the steel plant and petrochemical refinery, while Fe and Al were associated with road traffic emissions, and geogenic elements Ca, Mg, K, and Na were linked to marine spray and Saharan dust. This study demonstrates that combining multiple plant species with pollution indices can be a cost-effective biomonitoring approach for assessing air pollution and creating a high-density spatial monitoring network.

IPMCNet: A Lightweight Algorithm for Invasive Plant Multiclassification

Invasive plant species pose significant biodiversity and ecosystem threats. Real-time identification of invasive plants is a crucial prerequisite for early and timely prevention. While deep learning has shown promising results in plant recognition, the use of deep learning models often involve a large number of parameters and high data requirements for training. Unfortunately, the available data for various invasive plant species are often limited. To address this challenge, this study proposes a lightweight deep learning model called IPMCNet for the identification of multiple invasive plant species. IPMCNet attains high recognition accuracy even with limited data and exhibits strong generalizability. Simultaneously, by employing depth-wise separable convolutional kernels, splitting channels, and eliminating fully connected layer, the model’s parameter count is lower than that of some existing lightweight models. Additionally, the study explores the impact of different loss functions, and the insertion of various attention modules on the model’s accuracy. The experimental results reveal that, compared with eight other existing neural network models, IPMCNet achieves the highest classification accuracy of 94.52%. Furthermore, the findings suggest that focal loss is the most effective loss function. The performance of the six attention modules is suboptimal, and their insertion leads to a decrease in model accuracy.

C2-methyladenosine in tRNA promotes protein translation by facilitating the decoding of tandem m2A-tRNA-dependent codons

RNA modification C2-methyladenosine (m2A) exists in both rRNA and tRNA of Escherichia coli (E. coli), installed by the methyltransferase RlmN using a radical-S-adenosylmethionine (SAM) mechanism. However, the precise function of m2A in tRNA and its ubiquity in plants have remained unclear. Here we discover the presence of m2A in chloroplast rRNA and tRNA, as well as cytosolic tRNA, in multiple plant species. We identify six m2A-modified chloroplast tRNAs and two m2A-modified cytosolic tRNAs across different plants. Furthermore, we characterize three Arabidopsis m2A methyltransferases—RLMNL1, RLMNL2, and RLMNL3—which methylate chloroplast rRNA, chloroplast tRNA, and cytosolic tRNA, respectively. Our findings demonstrate that m2A37 promotes a relaxed conformation of tRNA, enhancing translation efficiency in chloroplast and cytosol by facilitating decoding of tandem m2A-tRNA-dependent codons. This study provides insights into the molecular function and biological significance of m2A, uncovering a layer of translation regulation in plants.

A robust and light-weight transfer learning-based architecture for accurate detection of leaf diseases across multiple plants using less amount of images.

Leaf diseases are a global threat to crop production and food preservation. Detecting these diseases is crucial for effective management. We introduce LeafDoc-Net, a robust, lightweight transfer-learning architecture for accurately detecting leaf diseases across multiple plant species, even with limited image data. Our approach concatenates two pre-trained image classification deep learning-based models, DenseNet121 and MobileNetV2. We enhance DenseNet121 with an attention-based transition mechanism and global average pooling layers, while MobileNetV2 benefits from adding an attention module and global average pooling layers. We deepen the architecture with extra-dense layers featuring swish activation and batch normalization layers, resulting in a more robust and accurate model for diagnosing leaf-related plant diseases. LeafDoc-Net is evaluated on two distinct datasets, focused on cassava and wheat leaf diseases, demonstrating superior performance compared to existing models in accuracy, precision, recall, and AUC metrics. To gain deeper insights into the model's performance, we utilize Grad-CAM++.

Formulation and effectivity of consortia of potential plant growth promoting endophytic bacteria from chickpea (Cicer arietinum)

A variety of bacterial genera coexists in natural environments and engages in mutualistic relationships that aid in their development and survival. The objective of this study was to prepare effective microbial consortia comprising potential endophytic bacteria that promote the growth of multiple plant species. These bacteria were isolated from the nodules and roots of Cicer arietinum. Five isolates, namely, CPJN13, CPSN8, CPHN4, CPHN2, and CPReR11, were selected to form the consortia. Compatibility tests were conducted to ensure the suitability of all isolates for consortia formation. Growth profile analyses indicated that the isolates exhibited rapid growth and were compatible. The consortia produced substantial amounts of indole-3-acetic acid, siderophores, and solubilized inorganic phosphate. In the pot experiment, there was significant enhancement in various plant growth parameters, including shoot and root length, as well as fresh and dry weight upon coinoculation of these cultures.

Mutualisms impact species' range expansion speeds and spatial distributions.

Species engage in mutually beneficial interspecific interactions (mutualisms) that shape their population dynamics in ecological communities. Species engaged in mutualisms vary greatly in their degree of dependence on their partner from complete dependence (e.g., yucca and yucca moth mutualism) to low dependence (e.g., generalist bee with multiple plant species). While current empirical studies show that, in mutualisms, partner dependence can alter the speed of a species' range expansion, there is no theory that provides conditions when expansion is sped up or slowed down. To address this, we built a spatially explicit model incorporating the population dynamics of two dispersing species interacting mutualistically. We explored how mutualisms impacted range expansion across a gradient of dependence (from complete independence to obligacy) between the two species. We then studied the conditions in which the magnitude of the mutualistic benefits could hinder versus enhance the speed of range expansion. We showed that either complete dependence, no dependence, or intermediate degree of dependence on a mutualist partner can lead to the greatest speeds of a focal species' range expansion based on the magnitude of benefits exchanged between partner species in the mutualism. We then showed how different degrees of dependence between species could alter the spatial distribution of the range expanding populations. Finally, we identified the conditions under which mutualistic interactions can turn exploitative across space, leading to the formation of a species' range limits. Our work highlights how couching mutualisms and mutualist dependence in a spatial context can provide insights about species range expansions, limits, and ultimately their distributions.

Transcriptome-Wide Identification of TCP Transcription Factor Family Members in Pinus massoniana and Their Expression in Regulation of Development and in Response to Stress

Pinus massoniana is an important coniferous tree species for barren mountain afforestation with enormous ecological and economic significance. It has strong adaptability to the environment. TEOSINTE BRANCHED 1/CYCLOIDEA/PCF (TCP) transcription factors (TFs) play crucial roles in plant stress response, hormone signal transduction, and development processes. At present, TCP TFs have been widely studied in multiple plant species, but research in P. massoniana has not been carried out. In this study, 13 PmTCP TFs were identified from the transcriptomes of P. massoniana. The phylogenetic results revealed that these PmTCP members were divided into two categories: Class I and Class II. Each PmTCP TF contained a conserved TCP domain, and the conserved motif types and numbers were similar in the same subgroup. According to the transcriptional profiling analysis under drought stress conditions, it was found that seven PmTCP genes responded to drought treatment to varying degrees. The qRT-PCR results showed that the majority of PmTCP genes were significantly expressed in the needles and may play a role in the developmental stage. Meanwhile, the PmTCPs could respond to several stresses and hormone treatments at different levels, which may be important for stress resistance. In addition, PmTCP7 and PmTCP12 were nuclear localization proteins, and PmTCP7 was a transcriptional suppressor. These results will help to explore the regulatory factors related to the growth and development of P. massoniana, enhance its stress resistance, and lay the foundation for further exploration of the physiological effects on PmTCPs.

Molecular evolution and interaction of 14-3-3 proteins with H+-ATPases in plant abiotic stresses.

Environmental stresses severely affect plant growth and crop productivity. Regulated by 14-3-3 proteins (14-3-3s), H+-ATPases (AHAs) are important proton pumps that can induce diverse secondary transport via channels and co-transporters for the abiotic stress response of plants. Many studies demonstrated the roles of 14-3-3s and AHAs in coordinating the processes of plant growth, phytohormone signaling, and stress responses. However, the molecular evolution of 14-3-3s and AHAs has not been summarized in parallel with evolutionary insights across multiple plant species. Here, we comprehensively review the roles of 14-3-3s and AHAs in cell signaling to enhance plant responses to diverse environmental stresses. We analyzed the molecular evolution of key proteins and functional domains that are associated with 14-3-3s and AHAs in plant growth and hormone signaling. The results revealed evolution, duplication, contraction, and expansion of 14-3-3s and AHAs in green plants. We also discussed the stress-specific expression of those 14-3-3and AHA genes in a eudicotyledon (Arabidopsis thaliana), a monocotyledon (Hordeum vulgare), and a moss (Physcomitrium patens) under abiotic stresses. We propose that 14-3-3s and AHAs respond to abiotic stresses through many important targets and signaling components of phytohormones, which could be promising to improve plant tolerance to single or multiple environmental stresses.

Tracking succession by means of 3D scans of plant communities in a glacier forefield to infer assembly processes

In primary successions, assembling plant communities are key for ecosystem functioning and stability. Often, plant successions are described on a taxonomic, functional and/or phylogenetic level, where species' identities, traits or evolutionary histories are considered. In this study, we exploited community features characterizing whole plant assemblages to capture emerging properties only available at the community level. Next to features aggregating over multiple plant species, we used a customized multispectral 3D plant scanner extracting digital community features as proxies for the frequency distribution of traits, productivity, prevalence of plant competition, and plant strategies and functions. Using these community features, we provide a comprehensive description of plant successions along glacier forefield. Additionally, we used a community feature‐based framework assessing the covariance of community feature dissimilarities and environmental dissimilarity to explore the mechanisms underlying plant community assemblies. Our data indicate a shift from fast‐growing and acquisitive, to slow‐growing and conservative plant strategies; increased productivity; higher competition between plant species; and an increasing contribution to the biogeomorphic stability along the successional gradient. Our results further indicate that stochastic processes dominate in early succession, whereas communities are mainly shaped by deterministic processes including environmental filtering and species interactions at late succession. We conclude that assessments of plant community features, facilitated by the use of field‐ready 3D scanners, provide complementary information to trait‐based approaches on the species level with implications for ecological processes.

Fluorescein staining of chloroplast starch granules in living plants.

Chloroplast starch granules (cpSGs) store energy harvested through photosynthesis in plants, and cpSG dynamics have important roles in plant energy metabolism and stress responses. To date, cpSGs have been visualized using several methods, such as iodine staining; however, no method can be used to specifically visualize cpSGs in living cells from various plant species. Here, we report a simple method to visualize cpSGs in living plant cells in various species by staining with fluorescein, a commonly used fluorescent dye. We show that fluorescein is taken up into chloroplasts and interacts with cpSGs similarly to iodine. Fluorescein also interacts with refined starch in vitro. Using a fluorescein derivative for ultrabright cpSG imaging, we produced high-quality 3D reconstructions of cpSGs and evaluated their accumulation in multiple plant species. As fluorescein is well known and readily purchasable, our fluorescein-based staining method should contribute to all research regarding starch.

Genome-Wide Identification of BrCAX Genes and Functional Analysis of BrCAX1 Involved in Ca2+ Transport and Ca2+ Deficiency-Induced Tip-Burn in Chinese Cabbage (Brassica rapa L. ssp. pekinensis).

Calcium (Ca2+) plays essential roles in plant growth and development. Ca2+ deficiency causes a physiological disorder of tip-burn in Brassiceae crops and is involved in the regulation of cellular Ca2+ homeostasis. Although the functions of Ca2+/H+ exchanger antiporters (CAXs) in mediating transmembrane transport of Ca2+ have been extensively characterized in multiple plant species, the potential roles of BrCAX genes remain unclear in Chinese cabbage. In this study, eight genes of the BrCAX family were genome-widely identified in Chinese cabbage. These BrCAX proteins contained conserved Na_Ca_ex domain and belonged to five members of the CAX family. Molecular evolutionary analysis and sequence alignment revealed the evolutionary conservation of BrCAX family genes. Expression profiling demonstrated that eight BrCAX genes exhibited differential expression in different tissues and under heat stress. Furthermore, Ca2+ deficiency treatment induced the typical symptoms of tip-burn in Chinese cabbage seedlings and a significant decrease in total Ca2+ content in both roots and leaves. The expression changes in BrCAX genes were related to the response to Ca2+ deficiency-induced tip-burn of Chinese cabbage. Specially, BrCAX1-1 and BrCAX1-2 genes were highly expressed gene members of the BrCAX family in the leaves and were significantly differentially expressed under Ca2+ deficiency stress. Moreover, overexpression of BrCAX1-1 and BrCAX1-2 genes in yeast and Chinese cabbage cotyledons exhibited a higher Ca2+ tolerance, indicating the Ca2+ transport capacity of BrCAX1-1 and BrCAX1-2. In addition, suppression expression of BrCAX1-1 and BrCAX1-2 genes reduced cytosolic Ca2+ levels in the root tips of Chinese cabbage. These results provide references for functional studies of BrCAX genes and to investigate the regulatory mechanisms underlying Ca2+ deficiency disorder in Brassiceae vegetables.

Exotic success following disturbance explained by weak native resilience and ruderal exotic bias

Abstract Disturbance is a primary driver of exotic plant invasions, but why disturbance commonly favours exotics over natives is unresolved. To address this question, we conducted the first biogeographic study of disturbance across multiple plant species. We experimentally disturbed grasslands and added seeds of 34 plant species to plots in their native range and in two introduced ranges that differed in invasibility (susceptibility to invasion) to evaluate recruitment while examining potential influences of resource availability, native community recovery from disturbance (resilience) and life‐history traits in local species pools. Species pools in the native (donor) range were more strongly skewed towards ruderal taxa than species pools in the introduced ranges. This bias in the donor pool was exacerbated by introduction filters that further selected for ruderal traits, strongly skewing exotic species pools in the introduced ranges towards ruderals. Sown species, which reflected these trait patterns, benefited from disturbance universally, but their disturbance response was 10‐fold greater in the more invasible introduced range. This result was not explained by nutrient availability, which responded similar to disturbance across ranges. Nor was it driven by background propagule pressure, which was minimal. Rather, the exaggerated disturbance effect in the more invasible introduced range appeared to be driven by weak recovery of the native plant community that allowed ruderal‐biased exotics to proliferate. Overall, disturbance appeared to favoured exotics because they were much more likely than natives to be ruderal. However, this trait bias only corresponded with an invader advantage in the more invasible range where weak community resilience was linked to slow‐growing, stress‐tolerant natives that failed to rapidly recover space and resources. In contrast, in the less invasible introduced range, highly competitive native perennials quickly filled the disturbance gap, demonstrating high community resilience that appeared to limit invader recruitment. Synthesis: Biogeographic influences on local species pools can facilitate invader success following disturbance, but final invasion outcomes are conditioned by native community resilience.

Genome Identification and Evolutionary Analysis of LBD Genes and Response to Environmental Factors in Phoebe bournei.

Phoebe bournei is nationally conserved in China due to its high economic value and positive effect on the ecological environment. P. bournei has an excellent wood structure, making it useful for industrial and domestic applications. Despite its importance, there are only a few studies on the lateral organ boundary domain (LBD) genes in P. bournei. The LBD gene family contributes to prompting rooting in multiple plant species and therefore supports their survival directly. To understand the LBD family in P. bournei, we verified its characteristics in this article. By comparing the sequences of Arabidopsis and identifying conserved domains and motifs, we found that there were 38 members of the LBD family in P. bournei, which were named PbLBD1 to PbLBD38. Through evolutionary analysis, we found that they were divided into two different populations and five subfamilies in total. The LBD gene family in P. bournei (Hemsl.) Yang species had two subfamilies, including 32 genes in Class I and 6 genes in Class II. It mainly consists of a Lateral Organ Boundary (LOB) conservative domain, and the protein structure is mostly "Y"-shaped. The gene expression pattern of the LBD gene family showed that the LBD genes were mainly expressed in lateral organs of plants, such as flowers and fruits. The response of LBD transcription factors to red and blue light was summarized, and several models of optogenetic expression regulation were proposed. The effect of regulatory mechanisms on plant rooting was also predicted. Moreover, quantitative real-time PCR (qRT-PCR) revealed that most PbLBDs were differentially expressed under cold, heat, drought, and salt stresses, indicating that PbLBDs might play different functions depending on the type of abiotic stress. This study provides the foundation for further research on the function of LBD in this tree species in the future.

Comparative Analysis of the PYL Gene Family in Three Ipomoea Species and the Expression Profiling of IbPYL Genes during Abiotic Stress Response in Sweetpotato.

Abscisic acid (ABA), a critical phytohormone that regulates plant development and stress response, is sensed by the ABA receptors PYR/PYL/RCAR (PYLs). The PYL genes have been widely studied in multiple plant species, while a systematic analysis of PYL genes in the genus Ipomoea remains unperformed. Here, a total of 13, 14, and 14 PYLs were identified in Ipomoea batatas, Ipomoea trifida, and Ipomoea triloba, respectively. Fragment duplication was speculated to play prominent roles in Ipomoea PYL gene expansions. These Ipomoea PYLs were classified into three subfamilies via phylogenetic analysis, which was supported by exon-intron structures and conserved motif analyses. Additionally, the interspecies collinearity analysis further depicted a potential evolutionary relationship between them. Moreover, qRT-PCR analysis showed that multiple IbPYLs are highly and differentially responsive to abiotic stress treatments, suggesting their potential roles in sweetpotato stress responses. Taken together, these data provide valuable insights into the PYLs in the genus Ipomoea, which may be useful for their further functional analysis of their defense against environmental changes.

PSW1, an LRR receptor kinase, regulates pod size in peanut.

Pod size is a key agronomic trait that greatly determines peanut yield, the regulatory genes and molecular mechanisms that controlling peanut pod size are still unclear. Here, we used quantitative trait locus analysis to identify a peanut pod size regulator, POD SIZE/WEIGHT1 (PSW1), and characterized the associated gene and protein. PSW1 encoded leucine-rich repeat receptor-like kinase (LRR-RLK) and positively regulated pod stemness. Mechanistically, this allele harbouring a 12-bp insertion in the promoter and a point mutation in the coding region of PSW1 causing a serine-to-isoleucine (S618I) substitution substantially increased mRNA abundance and the binding affinity of PSW1 for BRASSINOSTEROID INSENSITIVE1-ASSOCIATED RECEPTOR KINASE 1 (BAK1). Notably, PSW1HapII (super-large pod allele of PSW1) expression led to up-regulation of a positive regulator of pod stemness PLETHORA 1 (PLT1), thereby resulting in larger pod size. Moreover, overexpression of PSW1HapII increased seed/fruit size in multiple plant species. Our work thus discovers a conserved function of PSW1 that controls pod size and provides a valuable genetic resource for breeding high-yield crops.

Rice stripe virus nonstructural protein 3 suppresses plant defence responses mediated by the MEL-SHMT1 module.

Our previous study identified an evolutionarily conserved C4HC3-type E3 ligase, named microtubule-associated E3 ligase (MEL), that regulates broad-spectrum plant resistance against viral, fungal and bacterial pathogens in multiple plant species by mediating serine hydroxymethyltransferase (SHMT1) degradation via the 26S proteasome pathway. In the present study, we found that NS3 protein encoded by rice stripe virus could competitively bind to the MEL substrate recognition site, thereby inhibiting MEL interacting with and ubiquitinating SHMT1. This, in turn, leads to the accumulation of SHMT1 and the repression of downstream plant defence responses, including reactive oxygen species accumulation, mitogen-activated protein kinase pathway activation, and the up-regulation of disease-related gene expression. Our findings shed light on the ongoing arms race between pathogens and demonstrate how a plant virus can counteract the plant defence response.

A single MYB transcription factor with multiple functions during flower development.

Members of the R2R3-MYB transcription factor subgroup 19 (SG19) have been extensively studied in multiple plant species using different silenced or mutated lines. Some studies have proposed a function in flower opening, others in floral organ development/maturation, or specialized metabolism production. While SG19 members are clearly key players during flower development and maturation, the resulting picture is complex, confusing our understanding in how SG19 genes function. To clarify the function of the SG19 transcription factors, we used a single system, Petunia axillaris, and targeted its two SG19 members (EOB1 and EOB2) by CRISPR-Cas9. Although EOB1 and EOB2 are highly similar, they display radically different mutant phenotypes. EOB1 has a specific role in scent emission while EOB2 has pleiotropic functions during flower development. The eob2 knockout mutants reveal that EOB2 is a repressor of flower bud senescence by inhibiting ethylene production. Moreover, partial loss-of-function mutants (transcriptional activation domain missing) show that EOB2 is also involved in both petal and pistil maturation through regulation of primary and secondary metabolism. Here, we provide new insights into the genetic regulation of flower maturation and senescence. It also emphasizes the function of EOB2 in the adaptation of plants to specific guilds of pollinators.

Recent evolution of flowering time across multiple European plant species correlates with changes in aridity

Ongoing global warming and increasing drought frequencies impact plant populations and potentially drive rapid evolutionary adaptations. Historical comparisons, where plants grown from seeds collected in the past are compared to plants grown from freshly collected seeds from populations of the same sites, are a powerful method to investigate recent evolutionary changes across many taxa. We used 21–38 years old seeds of 13 European plant species, stored in seed banks and originating from Mediterranean and temperate regions, together with recently collected seeds from the same sites for a greenhouse experiment to investigate shifts in flowering phenology as a potential result of adaptive evolution to changes in drought intensities over the last decades. We further used single nucleotide polymorphism (SNP) markers to quantify relatedness and levels of genetic variation. We found that, across species, current populations grew faster and advanced their flowering. These shifts were correlated with changes in aridity at the population origins, suggesting that increased drought induced evolution of earlier flowering, whereas decreased drought lead to weak or inverse shifts in flowering phenology. In five out of the 13 species, however, the SNP markers detected strong differences in genetic variation and relatedness between the past and current populations collected, indicating that other evolutionary processes may have contributed to changes in phenotypes. Our results suggest that changes in aridity may have influenced the evolutionary trajectories of many plant species in different regions of Europe, and that flowering phenology may be one of the key traits that is rapidly evolving.