Review: Plant eco-evolutionary responses to climate change: Emerging directions

Herbivory and water availability interact to shape the adaptive landscape in the perennial forb, Boechera stricta

Abiotic and biotic factors interact to influence phenotypic evolution; however, identifying the causal agents of selection that drive the evolution and expression of traits remains challenging. In a field common garden, we manipulated water availability and herbivore abundance across 3 years, and evaluated clinal variation in functional traits and phenology, phenotypic plasticity, local adaptation, and selection using diverse accessions of the perennial forb, Boechera stricta. Consistent with expectations, drought stress exacerbated damage from herbivores. We found significant plasticity and genetic clines in foliar and phenological traits. Water availability and herbivory interacted to exert selection, even on traits like flowering duration, which showed no clinal variation. Furthermore, the direction of selection on specific leaf area in response to water availability mirrored the genetic cline and plasticity, suggesting that variation in water levels across the landscape influences the evolution of this trait. Finally, both herbivory and water availability likely contribute to local adaptation. This work emphasizes the additive and synergistic roles of abiotic and biotic factors in shaping phenotypic variation across environmental gradients.

Prickly Problems: Cylindropuntia's Low Genetic Diversity Despite Inbreeding Avoidance

Dioecy, the separation of sexes, is found in 6% of flowering plants. One widely known hypothesis suggests that it is an adaptation to mitigate inbreeding. A contrary hypothesis suggests that dioecy is an evolutionary dead end. However, contrasting patterns emerged from population genetic studies that compared the genetic diversity between dioecy versus hermaphroditic species. Specifically, in Silene, it was shown that dioecious species possess higher genetic diversity than hermaphroditic species, challenging the dead end hypothesis. To evaluate whether dioecy is indeed advantageous, further studies are needed in systems with diverse sexual systems such as the genus Cylindropuntia (Cactaceae). It encompasses species with sexual separation observed solely in polyploids. Notably, these polyploids (C. wolfii and C. chuckwallensis) share similar ploidy, flower colors, and geographic proximity, raising speculation about their shared ancestry. Moreover, C. wolfii has been reported to have a low seed production, highlighting the need to assess the reproductive strategies of the species. Our first goal was to compare the genetic diversity patterns among species with different sexual systems within the genus Cylindropuntia (Cactaceae). Our second goal was to investigate genetic shared ancestry among the polyploid species. As C. wolfii is struggling to sexually reproduce, our third objective was to investigate whether it is dominated by clonal reproduction, diversity parameters, and population structure. The clonality of C. wolfii was assessed using a combination of field survey and genetic analysis. The pattern of genetic diversity in species with diverse sexual systems did not support the dead end hypothesis. The field survey of C. wolfii revealed no seed recruitment, but the genetic analysis on the current adult plants showed low signs of clonality, suggesting that this species has recently shifted to clonal reproduction. Results showed that overall, this genus had low genetic diversity and high differentiation, implying that it is vulnerable to environmental threats.

Phenological sensitivity of Bromus tectorum genotypes depends on current and source environments

Plants respond to their environment with both short-term, within-generation trait plasticity, and long-term, between-generation evolutionary changes. However, the relative magnitude of plant responses to short- and long-term changes in the environment remains poorly understood. Shifts in phenological traits can serve as harbingers for responses to environmental change, and both a plant's current and source (i.e., genotype origin) environment can affect plant phenology via plasticity and local adaptation, respectively. To assess the role of current and source environments in explaining variation in flowering phenology of Bromus tectorum, an invasive annual grass, we conducted a replicated common garden experiment using 92 genotypes collected across western North America. Replicates of each genotype were planted in two densities (low = 100 seeds/1 m2, high = 100 seeds/0.04 m2) under two different temperature treatments (low = white gravel; high = black gravel; 2.1°C average difference) in a factorial design, replicated across four common garden locations in Idaho and Wyoming, USA. We tested for the effect of current environment (i.e., density treatment, temperature treatment, and common garden location), source environment (i.e., genotype source climate), and their interaction on each plant's flowering phenology. Flowering timing was strongly influenced by a plant's current environment, with plants that experienced warmer current climates and higher densities flowering earlier than those that experienced cooler current climates and lower densities. Genotypes from hot and dry source climates flowered consistently earlier than those from cool and wet source climates, even after accounting for genotype relatedness, suggesting that this genetically based climate cline is a product of natural selection. We found minimal evidence of interactions between current and source environments or genotype-by-environment interactions. Phenology was more sensitive to variation in the current climate than to variation in source climate. These results indicate that cheatgrass phenology reflects high levels of plasticity as well as rapid local adaptation. Both processes likely contribute to its current success as a biological invader and its capacity to respond to future environmental change.

The effect of global change on the expression and evolution of floral traits

BACKGROUND

Pollinators impose strong selection on floral traits, but other abiotic and biotic agents also drive the evolution of floral traits and influence plant reproduction. Global change is expected to have widespread effects on biotic and abiotic systems, resulting in novel selection on floral traits in future conditions.

SCOPE

Global change has depressed pollinator abundance and altered abiotic conditions, thereby exposing flowering plant species to novel suites of selective pressures. Here, we consider how biotic and abiotic factors interact to shape the expression and evolution of floral characteristics (the targets of selection), including floral size, colour, physiology, reward quantity and quality, and longevity, amongst other traits. We examine cases in which selection imposed by climatic factors conflicts with pollinator-mediated selection. Additionally, we explore how floral traits respond to environmental changes through phenotypic plasticity and how that can alter plant fecundity. Throughout this review, we evaluate how global change might shift the expression and evolution of floral phenotypes.

CONCLUSIONS

Floral traits evolve in response to multiple interacting agents of selection. Different agents can sometimes exert conflicting selection. For example, pollinators often prefer large flowers, but drought stress can favour the evolution of smaller flowers, and the size of floral organs can evolve as a trade-off between selection mediated by these opposing actors. Nevertheless, few studies have manipulated abiotic and biotic agents of selection factorially to disentangle their relative strengths and directions of selection. The literature has more often evaluated plastic responses of floral traits to stressors than it has considered how abiotic factors alter selection on these traits. Global change will likely alter the selective landscape through changes in the abundance and community composition of mutualists and antagonists and novel abiotic conditions. We encourage future work to consider the effects of abiotic and biotic agents of selection on floral evolution, which will enable more robust predictions about floral evolution and plant reproduction as global change progresses.

Arabidopsis CIRP1 E3 ligase modulates drought and oxidative stress tolerance and reactive oxygen species homeostasis by directly degrading catalases

Reactive oxygen species (ROS) plays critical roles in modulating plant growth and stress response and its homeostasis is fine tuned using multiple peroxidases. H2O2, a major kind of ROS, is removed rapidly and directly using three catalases, CAT1, CAT2, and CAT3, in Arabidopsis. Although the activity regulations of catalases have been well studied, their degradation pathway is less clear. Here, we report that CAT2 and CAT3 protein abundance was partially controlled using the 26S proteasome. To further identify candidate proteins that modulate the stability of CAT2, we performed yeast-two-hybrid screening and recovered several clones encoding a protein with RING and vWA domains, CIRP1 (CAT2 Interacting RING Protein 1). Drought and oxidative stress downregulated CIRP1 transcripts. CIRP1 harbored E3 ubiquitination activity and accelerated the degradation of CAT2 and CAT3 by direct interaction and ubiquitination. The cirp1 mutants exhibited stronger drought and oxidative stress tolerance, which was opposite to the cat2 and cat3 mutants. Genetic analysis revealed that CIRP1 acts upstream of CAT2 and CAT3 to negatively regulate drought and oxidative stress tolerance. The increased drought and oxidative stress tolerance of the cirp1 mutants was due to enhanced catalase (CAT) activities and alleviated ROS levels. Our data revealed that the CIRP1-CAT2/CAT3 module plays a vital role in alleviating ROS levels and balancing growth and stress responses in Arabidopsis.

Dressed Up to the Nines: The Interplay of Phytohormones Signaling and Redox Metabolism During Plant Response to Drought

Plants must effectively respond to various environmental stimuli to achieve optimal growth. This is especially relevant in the context of climate change, where drought emerges as a major factor globally impacting crops and limiting overall yield potential. Throughout evolution, plants have developed adaptative strategies for environmental stimuli, with plant hormones and reactive oxygen species (ROS) playing essential roles in their development. Hormonal signaling and the maintenance of ROS homeostasis are interconnected, playing indispensable roles in growth, development, and stress responses and orchestrating diverse molecular responses during environmental adversities. Nine principal classes of phytohormones have been categorized: auxins, brassinosteroids, cytokinins, and gibberellins primarily oversee developmental growth regulation, while abscisic acid, ethylene, jasmonic acid, salicylic acid, and strigolactones are the main orchestrators of environmental stress responses. Coordination between phytohormones and transcriptional regulation is crucial for effective plant responses, especially in drought stress. Understanding the interplay of ROS and phytohormones is pivotal for elucidating the molecular mechanisms involved in plant stress responses. This review provides an overview of the intricate relationship between ROS, redox metabolism, and the nine different phytohormones signaling in plants, shedding light on potential strategies for enhancing drought tolerance for sustainable crop production.

Heat waves induce milkweed resistance to a specialist herbivore via increased toxicity and reduced nutrient content

Over the last decade, a large effort has been made to understand how extreme climate events disrupt species interactions. Yet, it is unclear how these events affect plants and herbivores directly, via metabolic changes, and indirectly, via their subsequent altered interaction. We exposed common milkweed (Asclepias syriaca) and monarch caterpillars (Danaus plexippus) to control (26:14°C, day:night) or heat wave (HW) conditions (36:24°C, day:night) for 4 days and then moved each organism to a new control or HW partner to disentangle the direct and indirect effects of heat exposure on each organism. We found that the HW directly benefited plants in terms of growth and defence expression (increased latex exudation and total cardenolides) and insect her'bivores through faster larval development. Conversely, indirect HW effects caused both plant latex and total cardenolides to decrease after subsequent herbivory. Nonetheless, increasing trends of more toxic cardenolides and lower leaf nutritional quality after herbivory by HW caterpillars likely led to reduced plant damage compared to controls. Our findings reveal that indirect impacts of HWs may play a greater role in shaping plant-herbivore interactions via changes in key physiological traits, providing valuable understanding of how ecological interactions may proceed in a changing world.

Germination responses to changing rainfall timing reveal potential climate vulnerability in a clade of wildflowers

The seasonal timing of life history transitions is often critical to fitness, and many organisms rely upon environmental cues to match life cycle events with favorable conditions. In plants, the timing of seed germination is mediated by seasonal cues such as rainfall and temperature. Variation in cue responses among species can reflect evolutionary processes and adaptation to local climate and can affect vulnerability to changing conditions. Indeed, climate change is altering the timing of precipitation, and germination responses to such change can have consequences for individual fitness, population dynamics, and species distributions. Here, we assessed responses to the seasonal timing of germination-triggering rains for eleven species spanning the Streptanthus/Caulanthus clade (Brassicaceae). To do so, we experimentally manipulated the onset date of rainfall events, measured effects on germination fraction, and evaluated whether responses were constrained by evolutionary relationships across the phylogeny. We then explored the possible consequences of these responses to contemporary shifts in precipitation timing. Germination fractions decreased with later onset of rains and cooler temperatures for all but three Caulanthus species. Species' germination responses to the timing of rainfall and seasonal temperatures were phylogenetically constrained, with Caulanthus species appearing less responsive. Further, four species are likely already experiencing significant decreases in germination fractions with observed climate change, which has shifted the timing of rainfall towards the cooler, winter months in California. Overall, our findings emphasize the sensitivity of germination to seasonal conditions, underscore the importance of interacting environmental cues, and highlight vulnerability to shifting precipitation patterns with climate change, particularly in more northern, mesic species.

Climate change favors expansion of three Eucalyptus species in China

Eucalyptus has become one of the most widely planted species in tropical and subtropical regions in China, with important economic, ecological, and social values. However, it is currently unclear how climate change will affect different Eucalyptus species. Therefore, it is urgent to investigate the potential distribution and dynamics of Eucalyptus under current and future climate scenarios. In this study, we analyzed the potential distribution patterns of the three main Eucalyptus species (Eucalyptus grandis, Eucalyptus urophylla, and Eucalyptus tereticornis) under current and future climatic conditions (2041-2060 and 2061-2080) using the optimized MaxEnt model, which integrates a variety of environmental data including climate, topography, soil, and human influence. We also identified the main factors affecting the potential distributions of the three main Eucalyptus species. The model indicated that E. grandis exhibited heightened sensitivity to the mean temperature of the coldest quarter (7.0-20.0 °C) and annual mean temperature (11.9-24.2 °C), whereas E. urophylla displayed heightened sensitivity to precipitation of the warmest quarter (272-1694 mm) and annual precipitation (812-2624 mm). Conversely, E. tereticornis demonstrated heightened sensitivity to annual mean temperature (12.7-24.5 °C) and temperature seasonality (63.8-598.9). Under the current climate, E. tereticornis had the widest suitable distribution area (124.91 × 104 km²), followed by E. grandis (124.89 × 104 km²) and E. urophylla (119.81 × 104 km²). Under future climate change scenarios, the suitable ranges of E. grandis, E. urophylla and E. tereticornis will continue to expand. This study highlights the importance of climate change in Eucalyptus distribution and provides quantified potential distribution maps for three Eucalyptus species under current and future climate conditions in China. This research offers valuable scientific insights pertinent to the management and rational site selection for Eucalyptus plantations.

Unveiling the secrets of abiotic stress tolerance in plants through molecular and hormonal insights

Phytohormones are signaling substances that control essential elements of growth, development, and reactions to environmental stress. Drought, salt, heat, cold, and floods are a few examples of abiotic factors that have a significant impact on plant development and survival. Complex sensing, signaling, and stress response systems are needed for adaptation and tolerance to such pressures. Abscisic acid (ABA) is a key phytohormone that regulates stress responses. It interacts with the jasmonic acid (JA) and salicylic acid (SA) signaling pathways to direct resources toward reducing the impacts of abiotic stressors rather than fighting against pathogens. Under exposure to nanoparticles, the plant growth hormones also function as molecules that regulate stress and are known to be involved in a variety of signaling cascades. Reactive oxygen species (ROS) are detected in excess while under stress, and nanoparticles can control their formation. Understanding the way these many signaling pathways interact in plants will tremendously help breeders create food crops that can survive in deteriorating environmental circumstances brought on by climate change and that can sustain or even improve crop production. Recent studies have demonstrated that phytohormones, such as the traditional auxins, cytokinins, ethylene, and gibberellins, as well as more recent members like brassinosteroids, jasmonates, and strigolactones, may prove to be significant metabolic engineering targets for creating crop plants that are resistant to abiotic stress. In this review, we address recent developments in current understanding regarding the way various plant hormones regulate plant responses to abiotic stress and highlight instances of hormonal communication between plants during abiotic stress signaling. We also discuss new insights into plant gene and growth regulation mechanisms during stress, phytohormone engineering, nanotechnological crosstalk of phytohormones, and Plant Growth-Promoting Rhizobacteria's Regulatory Powers (PGPR) via the involvement of phytohormones.

Testing the evolutionary potential of an alpine plant: phenotypic plasticity in response to growth temperature outweighs parental environmental effects and other genetic causes of variation

Phenotypic plasticity and rapid evolution are fundamental processes by which organisms can maintain their function and fitness in the face of environmental changes. Here we quantified the plasticity and evolutionary potential of an alpine herb Wahlenbergia ceracea. Utilizing its mixed-mating system, we generated outcrossed and self-pollinated families that were grown in either cool or warm environments, and that had parents that had also been grown in either cool or warm environments. We then analysed the contribution of environmental and genetic factors to variation in a range of phenotypic traits including phenology, leaf mass per area, photosynthetic function, thermal tolerance, and reproductive fitness. The strongest effect was that of current growth temperature, indicating strong phenotypic plasticity. All traits except thermal tolerance were plastic, whereby warm-grown plants flowered earlier, grew larger, and produced more reproductive stems compared with cool-grown plants. Flowering onset and biomass were heritable and under selection, with early flowering and larger plants having higher relative fitness. There was little evidence for transgenerational plasticity, maternal effects, or genotype×environment interactions. Inbreeding delayed flowering and reduced reproductive fitness and biomass. Overall, we found that W. ceracea has the capacity to respond rapidly to climate warming via plasticity, and the potential for evolutionary change.

Selection on genome-wide gene expression plasticity of rice in wet and dry field environments

Gene expression can be highly plastic in response to environmental variation. However, we know little about how expression plasticity is shaped by natural selection and evolves in wild and domesticated species. We used genotypic selection analysis to characterize selection on drought-induced plasticity of over 7,500 leaf transcripts of 118 rice accessions (genotypes) from different environmental conditions grown in a field experiment. Gene expression plasticity was neutral for most gradually plastic transcripts, but transcripts with discrete patterns of expression showed stronger selection on expression plasticity. Whether plasticity was adaptive and co-gradient or maladaptive and counter-gradient varied among varietal groups. No transcripts that experienced selection for plasticity across environments showed selection against plasticity within environments, indicating a lack of evidence for costs of adaptive plasticity that may constrain its evolution. Selection on expression plasticity was influenced by degree of plasticity, transcript length and gene body methylation. We observed positive selection on plasticity of co-expression modules containing transcripts involved in photosynthesis, translation and responsiveness to abiotic stress. Taken together, these results indicate that patterns of selection on expression plasticity were context-dependent and likely associated with environmental conditions of varietal groups, but that the evolution of adaptive plasticity would likely not be constrained by opposing patterns of selection on plasticity within compared to across environments. These results offer a genome-wide view of patterns of selection and ecological constraints on gene expression plasticity and provide insights into the interplay between plastic and evolutionary responses to drought at the molecular level.

Plant adaptation to ionizing radiation: Mechanisms and patterns

Adaptation to environmental stressors is an essential property of plants that allows them, despite an immobile lifestyle, to survive in a changeable environment. The chain of successive events culminating in the final radiobiological reaction begins with the absorption of energy of ionizing radiation in the cell. Starting from stochastic acts of molecular injury formation, radiation damage gradually acquires deterministic features, which are expressed in a limited number of phenomena that complete plant radiation damage. As plants undergo specialization, the differences between plants and animals become more pronounced, leading to distinct responses to radiation. Chronic radiation exposure may activate biological mechanisms resulting in increased radioresistance of the population. The higher the level of radiation exposure and the sensitivity of plants to radiation, the more intensive the selection. Depending on the circumstances, enhanced radioresistance of a population can be achieved in different ways or has not evolved at all. High dose rates of chronic irradiation leаd to selection for the efficiency of repair systems, while low dose rates activate epigenetic mechanisms that lead to the maintenance of oxidative balance, additional synthesis of chaperones, and control of TEs transposition. Due to huge differences in the radiosensitivity of organisms that make up the ecosystem, irradiation can result in disruption of connections between components of ecosystems which may lead to consequences that can differ drastically from those expected at the organismal and population levels. Therefore, the use of ecological knowledge is essential for understanding the responses of populations and ecosystems to radiation exposure.

Genomics for monitoring and understanding species responses to global climate change

All life forms across the globe are experiencing drastic changes in environmental conditions as a result of global climate change. These environmental changes are happening rapidly, incur substantial socioeconomic costs, pose threats to biodiversity and diminish a species' potential to adapt to future environments. Understanding and monitoring how organisms respond to human-driven climate change is therefore a major priority for the conservation of biodiversity in a rapidly changing environment. Recent developments in genomic, transcriptomic and epigenomic technologies are enabling unprecedented insights into the evolutionary processes and molecular bases of adaptation. This Review summarizes methods that apply and integrate omics tools to experimentally investigate, monitor and predict how species and communities in the wild cope with global climate change, which is by genetically adapting to new environmental conditions, through range shifts or through phenotypic plasticity. We identify advantages and limitations of each method and discuss future research avenues that would improve our understanding of species' evolutionary responses to global climate change, highlighting the need for holistic, multi-omics approaches to ecosystem monitoring during global climate change.

The impact of multifactorial stress combination on plants, crops, and ecosystems: how should we prepare for what comes next?

The complexity of environmental conditions encountered by plants in the field, or in nature, is gradually increasing due to anthropogenic activities that promote global warming, climate change, and increased levels of pollutants. While in the past it seemed sufficient to study how plants acclimate to one or even two different stresses affecting them simultaneously, the complex conditions developing on our planet necessitate a new approach of studying stress in plants: Acclimation to multiple stress conditions occurring concurrently or consecutively (termed, multifactorial stress combination [MFSC]). In an initial study of the plant response to MFSC, conducted with Arabidopsis thaliana seedlings subjected to an MFSC of six different abiotic stresses, it was found that with the increase in the number and complexity of different stresses simultaneously impacting a plant, plant growth and survival declined, even if the effects of each stress involved in such MFSC on the plant was minimal or insignificant. In three recent studies, conducted with different crop plants, MFSC was found to have similar effects on a commercial rice cultivar, a maize hybrid, tomato, and soybean, causing significant reductions in growth, biomass, physiological parameters, and/or yield traits. As the environmental conditions on our planet are gradually worsening, as well as becoming more complex, addressing MFSC and its effects on agriculture and ecosystems worldwide becomes a high priority. In this review, we address the effects of MFSC on plants, crops, agriculture, and different ecosystems worldwide, and highlight potential avenues to enhance the resilience of crops to MFSC.

Feedback regulation of the isoprenoid pathway by SsdTPS overexpression has the potential to enhance plant tolerance to drought stress

In order to maintain the dynamic physiological balance, plants are compelled to adjust their energy metabolism and signal transduction to cope with the abiotic stresses caused by complex and changeable environments. The diterpenoid natural compound and secondary metabolites, sclareol, derived from Salvia sclarea, has gained significant attention owing to its economic value as a spice material and diverse physiological activities. Here, we focused on the roles and regulatory mechanisms of the sclareol diterpene synthase gene SsdTPS in the resistance of S. sclarea to abiotic stresses. Our results suggested that abiotic stresses could induce the response and upregulation of SsdTPS expression and isoprenoid pathway in S. sclarea. Ectopic expression of SsdTPS conferred drought tolerance in transgenic Arabidopsis, compared with wild-type. Overexpression of SsdTPS enhanced the transcription of ABA signal transduction synthetic regulators and induced the positive feedback upregulating key regulatory genes in the MEP pathway, thereby promoting the increase of ABA content and improving drought tolerance in transgenic plants. In addition, SsdTPS-overexpressed transgenic Arabidopsis improved the responses of stomatal regulatory genes and ROS scavenging enzyme activities and gene expression to drought stress. This promoted the stomatal closure and ROS reduction, thus enhancing water retention capacity and reducing oxidative stress damage. These findings unveil the potentially positive role of SsdTPS in orchestrating multiple regulatory mechanisms and maintaining homeostasis for improved abiotic stress resistance in S. sclarea, providing a novel insight into strategies for promoting drought resistance and cultivating highly tolerant plants.

Resurrected seeds from herbarium specimens reveal rapid evolution of drought resistance in a selfing annual

PREMISE

Increased aridity and drought associated with climate change are exerting unprecedented selection pressures on plant populations. Whether populations can rapidly adapt, and which life history traits might confer increased fitness under drought, remain outstanding questions.

METHODS

We utilized a resurrection ecology approach, leveraging dormant seeds from herbarium collections to assess whether populations of Plantago patagonica from the semi-arid Colorado Plateau have rapidly evolved in response to approximately ten years of intense drought in the region. We quantified multiple traits associated with drought escape and drought resistance and assessed the survival of ancestors and descendants under simulated drought.

RESULTS

Descendant populations displayed a significant shift in resource allocation, in which they invested less in reproductive tissues and relatively more in both above- and below-ground vegetative tissues. Plants with greater leaf biomass survived longer under terminal drought; moreover, even after accounting for the effect of increased leaf biomass, descendant seedlings survived drought longer than their ancestors.

CONCLUSIONS

Our results document rapid adaptive evolution in response to climate change in a selfing annual and suggest that shifts in tissue allocation strategies may underlie adaptive responses to drought in arid or semi-arid environments. This work also illustrates a novel approach, documenting that under specific circumstances, seeds from herbarium specimens may provide an untapped source of dormant propagules for future resurrection experiments.

Auxin and abiotic stress responses

Plants are exposed to a variety of abiotic stresses; these stresses have profound effects on plant growth, survival, and productivity. Tolerance and adaptation to stress require sophisticated stress sensing, signaling, and various regulatory mechanisms. The plant hormone auxin is a key regulator of plant growth and development, playing pivotal roles in the integration of abiotic stress signals and control of downstream stress responses. In this review, we summarize and discuss recent advances in understanding the intersection of auxin and abiotic stress in plants, with a focus on temperature, salt, and drought stresses. We also explore the roles of auxin in stress tolerance and opportunities arising for agricultural applications.

Genome-Wide Identification and Expression Analysis of Cysteine-Rich Polycomb-like Protein (CPP) Gene Family in Tomato

The cysteine-rich polycomb-like protein (CPP) gene family is a class of transcription factors containing conserved cysteine-rich CRC structural domains that is involved in the regulation of plant growth and stress tolerance to adversity. Relative to other gene families, the CPP gene family has not received sufficient attention. In this study, six SlCPPs were identified for the first time using the most recent genome-wide identification data of tomato. Subsequently, a phylogenetic analysis classified SlCPPs into four subfamilies. The analysis of cis-acting elements in the promoter indicates that SlCPPs are involved in plant growth and development and also stress response. We present for the first time the prediction of the tertiary structure of these SlCPPs proteins using the AlphaFold2 artificial intelligence system developed by the DeepMind team. Transcriptome data analysis showed that SlCPPs were differentially expressed in different tissues. Gene expression profiling showed that all SlCPPs except SlCPP5 were up-regulated under drought stress; SlCPP2, SlCPP3 and SlCPP4 were up-regulated under cold stress; SlCPP2 and SlCPP5 were up-regulated under salt stress; all SlCPPs were up-regulated under inoculation with Cladosporium fulvum; and SlCPP1, SlCPP3, and SlCPP4 were up-regulated under inoculation with Stemphylium lycopersici. We performed a virus-induced gene silencing experiment on SlCPP3, and the results indicated that SlCPP3 was involved in the response to drought stress. Finally, we predicted the interaction network of the key gene SlCPP3, and there was an interaction relationship between SlCPP3 and 10 genes, such as RBR1 and MSI1. The positive outcome showed that SlCPPs responded to environmental stress. This study provides a theoretical and empirical basis for the response mechanisms of tomato in abiotic stresses.

Facilitated Adaptation as A Conservation Tool in the Present Climate Change Context: A Methodological Guide

Climate change poses a novel threat to biodiversity that urgently requires the development of adequate conservation strategies. Living organisms respond to environmental change by migrating to locations where their ecological niche is preserved or by adapting to the new environment. While the first response has been used to develop, discuss and implement the strategy of assisted migration, facilitated adaptation is only beginning to be considered as a potential approach. Here, we present a review of the conceptual framework for facilitated adaptation, integrating advances and methodologies from different disciplines. Briefly, facilitated adaptation involves a population reinforcement that introduces beneficial alleles to enable the evolutionary adaptation of a focal population to pressing environmental conditions. To this purpose, we propose two methodological approaches. The first one (called pre-existing adaptation approach) is based on using pre-adapted genotypes existing in the focal population, in other populations, or even in closely related species. The second approach (called de novo adaptation approach) aims to generate new pre-adapted genotypes from the diversity present in the species through artificial selection. For each approach, we present a stage-by-stage procedure, with some techniques that can be used for its implementation. The associated risks and difficulties of each approach are also discussed.

Plant Species' Capacity for Range Shifts at the Habitat and Geographic Scales: A Trade-Off-Based Framework

Climate change is causing rapid shifts in the abiotic and biotic environmental conditions experienced by plant populations, but we lack generalizable frameworks for predicting the consequences for species. These changes may cause individuals to become poorly matched to their environments, potentially inducing shifts in the distributions of populations and altering species' habitat and geographic ranges. We present a trade-off-based framework for understanding and predicting whether plant species may undergo range shifts, based on ecological strategies defined by functional trait variation. We define a species' capacity for undergoing range shifts as the product of its colonization ability and the ability to express a phenotype well-suited to the environment across life stages (phenotype-environment matching), which are both strongly influenced by a species' ecological strategy and unavoidable trade-offs in function. While numerous strategies may be successful in an environment, severe phenotype-environment mismatches result in habitat filtering: propagules reach a site but cannot establish there. Operating within individuals and populations, these processes will affect species' habitat ranges at small scales, and aggregated across populations, will determine whether species track climatic changes and undergo geographic range shifts. This trade-off-based framework can provide a conceptual basis for species distribution models that are generalizable across plant species, aiding in the prediction of shifts in plant species' ranges in response to climate change.

Establishment of mountain birch (Betula pubescens ssp. tortuosa) on a glacial outwash plain: Spatial patterns and decadal processes

Most of the Earth's surface has now been modified by humans. In many countries, natural and semi-natural ecosystems mostly occur as islands, isolated by land converted for agriculture and a variety of other land-uses. In this fragmented state, long-distance dispersal may be the only option for species to adapt their ranges in response to changing climate. The order of arrival of species may leave a lasting imprint on community assembly. Although mostly studied at and above the species level, such priority effects also apply at the intraspecific level. We suggest that this may be particularly important in subarctic and arctic ecosystems. Mountain birch (Betula pubescens ssp. tortuosa) is characterized by great intraspecific variation. We explored spatio-temporal patterns of the first two mountain birch generations on a homogeneous, early successional glacial outwash plain in SE Iceland that was the recipient of spatially extensive long-distance dispersal ca. 30 years ago. We evaluated the decadal progress of the young population by remeasuring in 2018, tree density and growth form, plant size, and reproductive effort on 30 transects (150 m2) established in 2008 at four sites on the plain and two adjacent sites ca. 10 km away. All measured variables showed positive increases, but contrary to our predictions of converging dynamics among sites, they had significantly diverged. Thus, two of the sites (only 500 m apart) could not be distinguished in 2008, but by 2018, one of them had much faster growth rates than the other, a higher growth form index reflecting more upright tree stature, greater reproductive effort, and much greater second-generation seedling recruitment. We discuss two hypotheses that may explain the diverging dynamics, site-scale environmental heterogeneity, and legacies of intraspecific priority effects.

Is There Spatial and Temporal Variability in the Response of Plant Canopy and Trunk Growth to Climate Change in a Typical River Basin of Arid Areas

The response of plants to climate change has become a topical issue. However, there is no consensus on the synergistic processes of the canopy and trunk growth within different vegetation types, or on the consistency of the response of the canopy and trunk to climate change. This paper is based on Normalized Difference Vegetation Index (NDVI), tree-ring width index (TRW) and climate data from the Irtysh River basin, a sensitive area for climate change in Central Asia. Spatial statistical methods and correlation analysis were used to analyze the spatial and temporal trends of plants and climate, and to reveal the differences in the canopy and trunk response mechanisms to climate within different vegetation types. The results show a warming and humidifying trend between 1982 and 2015 in the study area, and NDVI and TRW increases in different vegetation type zones. On an interannual scale, temperature is the main driver of the canopy growth in alpine areas and precipitation is the main limiting factor for the canopy growth in lower altitude valley and desert areas. The degree of response of the trunk to climatic factors decreases with increasing altitude, and TRW is significantly correlated with mean annual temperature, precipitation and SPEI in desert areas. On a monthly scale, the earlier and longer growing season due to the accumulation of temperature and precipitation in the early spring and late autumn periods contributes to two highly significant trends of increase in the canopy from March to May and August to October. Climatic conditions during the growing season are the main limiting factor for the growth of the trunk, but there is considerable variation in the driving of the trunk in different vegetation type zones. The canopy growth is mainly influenced by climatic factors in the current month, while there is a 1–2-month lag effect in the response of the trunk to climatic factors. In addition, the synergy between the canopy and the trunk is gradually weakened with increasing altitude (correlation coefficient is 0.371 in alpine areas, 0.413 in valley areas and 0.583 in desert areas). These findings help to enrich the understanding of the response mechanisms to climate change in different vegetation type zones and provide a scientific basis for the development of climate change response measures in Central Asia.

Plant hormone regulation of abiotic stress responses

Plant hormones are signalling compounds that regulate crucial aspects of growth, development and environmental stress responses. Abiotic stresses, such as drought, salinity, heat, cold and flooding, have profound effects on plant growth and survival. Adaptation and tolerance to such stresses require sophisticated sensing, signalling and stress response mechanisms. In this Review, we discuss recent advances in understanding how diverse plant hormones control abiotic stress responses in plants and highlight points of hormonal crosstalk during abiotic stress signalling. Control mechanisms and stress responses mediated by plant hormones including abscisic acid, auxin, brassinosteroids, cytokinins, ethylene and gibberellins are discussed. We discuss new insights into osmotic stress sensing and signalling mechanisms, hormonal control of gene regulation and plant development during stress, hormone-regulated submergence tolerance and stomatal movements. We further explore how innovative imaging approaches are providing insights into single-cell and tissue hormone dynamics. Understanding stress tolerance mechanisms opens new opportunities for agricultural applications.

Influence of Climate Change on Metabolism and Biological Characteristics in Perennial Woody Fruit Crops in the Mediterranean Environment

The changes in the state of the climate have a high impact on perennial fruit crops thus threatening food availability. Indeed, climatic factors affect several plant aspects, such as phenological stages, physiological processes, disease-pest frequency, yield, and qualitative composition of the plant tissues and derived products. To mitigate the effects of climatic parameters variability, plants implement several strategies of defense, by changing phenological trends, altering physiology, increasing carbon sequestration, and metabolites synthesis. This review was divided into two sections. The first provides data on climate change in the last years and a general consideration on their impact, mitigation, and resilience in the production of food crops. The second section reviews the consequences of climate change on the industry of two woody fruit crops models (evergreen and deciduous trees). The research focused on, citrus, olive, and loquat as evergreen trees examples; while grape, apple, pear, cherry, apricot, almond, peach, kiwi, fig, and persimmon as deciduous species. Perennial fruit crops originated by a complex of decisions valuable in a long period and involving economic and technical problems that farmers may quickly change in the case of annual crops. However, the low flexibility of woody crops is balanced by resilience in the long-life cycle.

The macroecology of plant populations from local to global scales

Population ecologists develop theoretical and pragmatic knowledge of how and why populations change or remain stable, how life histories evolve and devise management strategies for populations of concern. However, forecasting the effects of global change or recommending management strategies is often urgent, requiring ecologists to work without detailed local evidence while using data and models from outside the focal location or species. Here we explore how the comparative ecology of populations, population macroecology, can be used to develop generalisations within and between species across different scales, using available demographic, environmental, life history, occurrence and trait data. We outline the strengths and weaknesses of using broad climatic variables and suitability inferred from probability of occupancy models to represent environmental variation in comparative analyses. We evaluate the contributions of traits, environment and their interaction as drivers of life history strategy. We propose that insights from life history theory, together with the adaptive capacity of populations and individuals, can inform on 'persist in place' vs 'shift in space' responses to changing conditions. As demographic data accumulate at landscape and regional scales for single species, and throughout plant phylogenies, we will have new opportunities for testing macroecological generalities within and across species.

Rapid, parallel evolution of field mustard (Brassica rapa) under experimental drought

Climate change is driving evolutionary and plastic responses in populations, but predicting these responses remains challenging. Studies that combine experimental evolution with ancestor-descendant comparisons allow assessment of the causes, parallelism, and adaptive nature of evolutionary responses, although such studies remain rare, particularly in a climate change context. Here, we created experimental populations of Brassica rapa derived from the same natural population and exposed these replicated populations to experimental drought or watered conditions for four generations. We then grew ancestors and descendants concurrently, following the resurrection approach. Experimental populations under drought showed rapid evolution of earlier flowering time and increased specific leaf area, consistent with a drought escape strategy and observations in natural populations. Evolutionary shifts followed the direction of selection and increased fitness under drought, indicative of adaptive evolution. Evolution to drought also occurred largely in parallel among replicate populations. Further, traits showed phenotypic plasticity to drought, but the direction and effect size of plasticity varied. Our results demonstrate parallel evolution to experimental drought, suggesting that evolution to strong, consistent selection may be predictable. Broadly, our study demonstrates the utility of combining experimental evolution with the resurrection approach to investigate responses to climate change.

Photosynthesis and chloroplast redox signaling in the age of global warming: stress tolerance, acclimation, and developmental plasticity

Contemporary climate change is characterized by the increased intensity and frequency of environmental stress events such as floods, droughts, and heatwaves, which have a debilitating impact on photosynthesis and growth, compromising the production of food, feed, and biofuels for an expanding population. The need to increase crop productivity in the context of global warming has fueled attempts to improve several key plant features such as photosynthetic performance, assimilate partitioning, and tolerance to environmental stresses. Chloroplast redox metabolism, including photosynthetic electron transport and CO2 reductive assimilation, are primary targets of most stress conditions, leading to excessive excitation pressure, photodamage, and propagation of reactive oxygen species. Alterations in chloroplast redox poise, in turn, provide signals that exit the plastid and modulate plant responses to the environmental conditions. Understanding the molecular mechanisms involved in these processes could provide novel tools to increase crop yield in suboptimal environments. We describe herein various interventions into chloroplast redox networks that resulted in increased tolerance to multiple sources of environmental stress. They included manipulation of endogenous components and introduction of electron carriers from other organisms, which affected not only stress endurance but also leaf size and longevity. The resulting scenario indicates that chloroplast redox pathways have an important impact on plant growth, development, and defense that goes beyond their roles in primary metabolism. Manipulation of these processes provides additional strategies for the design of crops with improved performance under destabilized climate conditions as foreseen for the future.

Protective Role of Ice Barriers: How Reproductive Organs of Early Flowering and Mountain Plants Escape Frost Injuries

In the temperate zone of Europe, plants flowering in early spring or at high elevation risk that their reproductive organs are harmed by episodic frosts. Focusing on flowers of two mountain and three early-flowering colline to montane distributed species, vulnerability to ice formation and ice management strategies using infrared video thermography were investigated. Three species had ice susceptible flowers and structural ice barriers, between the vegetative and reproductive organs, that prevent ice entrance from the frozen stems. Structural ice barriers as found in Anemona nemorosa and Muscari sp. have not yet been described for herbaceous species that of Jasminum nudiflorum corroborates findings for woody species. Flowers of Galanthus nivalis and Scilla forbesii were ice tolerant. For all herbs, it became clear that the soil acts as a thermal insulator for frost susceptible below ground organs and as a thermal barrier against the spread of ice between individual flowers and leaves. Both ice barrier types presumably promote that the reproductive organs can remain supercooled, and can at least for a certain time-period escape from effects of ice formation. Both effects of ice barriers appear significant in the habitat of the tested species, where episodic freezing events potentially curtail the reproductive success.

The Challenge in the Management of Historic Trees in Urban Environments during Climate Change: The Case of Corso Trieste (Rome, Italy)

This study carries out a quantitative analysis of the impact on microclimate (air temperature and thermal comfort) of a row of 165 historical Pinus pinea L. located in a central neighbourhood of Rome (Italy). The analysis starts from a qualitative general analysis on the stressful conditions leading to tree decline in the urban environment especially during extreme climate change phenomena. Subsequently, the effects of planting new types of trees are assessed using ENVI-met, a 3D prognostic non-hydrostatic model for the simulation of surface-plant-air interactions. Results, obtained by simulating three different scenarios in which the trees are first removed and then modified, show that a gradual renewal of the existing trees, based on priority criteria of maturity or senescence, vegetative and phytosanitary conditions, efficiency of ecosystem services and safety for citizens, has positive effects on thermal comfort. By integrating current results and scientific literature, the final aim of this work is to provide stakeholders with a strategic and systemic planning methodology, which, based on the innovative integrated use of tree management and modelling tools, may (i) enhance the benefits of greening in a scenario of climate change and (ii) lead to intervention strategies based on complementarity between conservation of existing trees and tree renewal.