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Summary: Drought is intensifying globally with climate change, creating an urgency to understand ecosystem response to drought both during and after these events end to limit loss of ecosystem functioning. The literature is replete with studies of how ecosystems respond during drought, yet there are far fewer studies focused on ecosystem dynamics after drought ends. Furthermore, while the terms used to describe drought can be variable and inconsistent, so can those that describe ecosystem responses following drought. With this review, we sought to evaluate and create clear definitions of the terms that ecologists use to describe post‐drought responses. We found that legacy effects, resilience and recovery were used most commonly with respect to post‐drought ecosystem responses, but the definitions used to describe these terms were variable. Based on our review of the literature, we propose a framework for generalizing ecosystem responses after drought ends, which we refer to as 'the post‐drought period'. We suggest that future papers need to clearly describe characteristics of the imposed drought, and we encourage authors to use the term post‐drought period as a general term that encompasses responses after drought ends and use other terms as more specific descriptors of responses during the post‐drought period. [ABSTRACT FROM AUTHOR]

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Yoselin Benitez Alfonso, a professor in interdisciplinary plant sciences at the University of Leeds, shares her journey and passion for plant science. Growing up in Cuba, she developed a love for nature and later pursued a degree in chemistry in Spain. Despite not having a biology background, she taught herself plant biology and became interested in plasmodesmata research. She is motivated by her love for research, the success of her students, and the impact of her contributions to teaching and diversity. She considers her father and various mentors as role models and enjoys reading papers on plasmodesmata research and plant symbiosis. Her favorite plant is the olive tree due to its symbolism, climate resilience, and economic significance. Yoselin is also involved in the Black in Plant Science Network and has received recognition for her leadership and academic achievements. [Extracted from the article]

The Holocene history of the forest-alpine tundra ecotone in Central Sweden (Scandes Mountains) is inferred from radiocarbon analyses of subfossil wood remains. Pinus sylvestris was the dominant subalpine tree species during the early Holocene, when it ascended almost 200 m higher than currently. A short climatic episode (less than 100 years) is postulated to have triggered erosional processes around 6300 B.P., and extinguished the upper part of the subalpine pine woodland. Subsequently, a subalpine belt of Betula pubescens ssp. tortuosa and Alnus incana developed. A Holocene thermal optimum occurred around 6100 B.p., when the birch/alder belt flourished and the tree-limits probably reached their highest levels during the Holocene. Shortly after 6000 B.P., a long-term pine forest retrogression started and the birch/alder belt was disrupted by expanding snow-beds. Pine receded slightly at its tree-limit, but the uppermost belt of closed pine forest (presently dominated by birch) remained intact until c. 3300 B.p., when a severe climatic deterioration occurred. The present-day subalpine belt of pure birch forest developed successively and increased in vertical extent after c. 5300 B.P., when summer temperature declined. The evolution of the birch belt is postulated to have been ultimately a response to decreased seasonality, which favoured birch at the expense of pine. Because of the 'inertia' characterizing the highest pine forest, the birch belt was relatively narrow until a major thermal decline c. 3300 B.P., when it made a massive downslope expansion. The latest phase of pine recession was during the Little Ice Age, 800-300B.P. [ABSTRACT FROM AUTHOR]

The article comments on the prominence of papers featured in the "New Phytologist" journal that consider various aspects of plant interactions with the environment. The author believes that the relative change in scope can be traced back over more than a century that the journal has been published. The coordinated efforts of scientists are needed to respond to the challenges posed by atmospheric and climactic change.

Summary: Climate change has advanced plant phenology globally 4–6 d °C−1 on average. Such shifts are some of the most reported and predictable biological impacts of rising temperatures. Yet as climate change has marched on, phenological shifts have appeared muted over recent decades – failing to match simple predictions of an advancing spring with continued warming. The main hypothesis for these changing trends is that interactions between spring phenological cues – long‐documented in laboratory environments – are playing a greater role in natural environments due to climate change. Here, we argue that accurately linking shifts observed in long‐term data to underlying phenological cues is slowed by biases in observational studies and limited integration of insights from laboratory studies. We synthesize seven decades of laboratory experiments to quantify how phenological cue‐space has been studied and how treatments compare with shifts caused by climate change. Most studies focus on one cue, limiting our ability to make accurate predictions, but some well‐studied forest species offer opportunities to advance forecasting. We outline how greater integration of controlled‐environment studies with long‐term data could drive a new generation of laboratory experiments, built on physiological insights, that would transform our fundamental understanding of phenology and improve predictions. [ABSTRACT FROM AUTHOR]

The Postglacial history of Alnus is of particular relevance to the palaeoecology of wetlands and floodplains. The ecological histories of floodplain sites differ from those on dry-land or from hydroseres. This paper uses pollen percentage and influx data to investigate floodplain succession and woodland development on floodplains in the West Midlands, the primary site being Wilden Marsh near Stourport, Worcestershire. The floodplain at Wilden probably underwent a three-phase succession during the early Postglacial; Betula was replaced by Salix spp. which were out-competed by Alnus. Alnus was present prior to its expansion, which is seen as the result of increasing soil stability, pedogenesis and decreased free drainage related to floodplain development and not necessarily to climatic change or anthropogenic disturbance. During the late Postglacial Alnus declines and Salix frequently increases again due to floodplain deforestation and utilisation, which was partly facilitated by altered soil conditions caused by hydrological change. The advantages of small floodplain sites for the differentiation of vegetation pattern is illustrated by the identification of a non-floodplain pollen component dominated by Tilia. [ABSTRACT FROM AUTHOR]

The authors discuss the paper of Qi and colleagues which focuses on the response of relict genus Cercidiphyllum to climatic or geological changes using genetic information from chloroplast (cp) and nuclear DNAs. They mention that Qi and colleagues who used ecological niche modelling (ENM) estimated that the specie split from its sister lineage during late Cretaceous period based on cpDNA evidence. They state that the paper draws detailed pictured o the evolutionary history of Cercidiphyllum.

Biogeography, climate change, early career researcher, ecophysiology, functional traits, intraspecific variation, trees, Tansley Medal Keywords: biogeography; climate change; early career researcher; ecophysiology; functional traits; intraspecific variation; Tansley Medal; trees EN biogeography climate change early career researcher ecophysiology functional traits intraspecific variation Tansley Medal trees 1962 1963 2 02/21/23 20230315 NES 230315 What inspired your interest in plant science? The answer - that hot droughts are especially hard on trees, and that climate change was super-charging the frequency and severity of hot droughts - drove home to me that climate change is happening now. [Extracted from the article]

As a result of the late Quaternary megafaunal extinctions (50 000-10 000 before present ( BP)), most continents today are depauperate of megaherbivores. These extinctions were time-transgressive, size- and taxonomically selective, and were caused by climate change, human hunting, or both. The surviving megaherbivores often act as ecological keystones, which was likely true in the past. In spite of this and extensive research on the causes of the Late Quaternary Extinctions, the long-term ecological consequences of the loss of the Pleistocene megafauna remained unknown until recently, due to difficulties in linking changes in flora and fauna in paleorecords. The quantification of Sporormiella and other dung fungi have recently allowed for explicit tests of the ecological consequences of megafaunal extirpations in the fossil pollen record. In this paper, I review the impacts of the loss of keystone megaherbivores on vegetation in several paleorecords. A growing number of studies support the hypothesis that the loss of the Pleistocene megafauna resulted in cascading effects on plant community composition, vegetation structure and ecosystem function, including increased fire activity, novel communities and shifts in biomes. Holocene biota thus exist outside the broader evolutionary context of the Cenozoic, and the Late Quaternary Extinctions represent a regime shift for surviving plant and animal species. [ABSTRACT FROM AUTHOR]

Information about several papers discussed at a meeting held August 2011 sponsored by the Ecological Society of America on experiments which examine the effects of global change on carbon storage and exchange is presented. Topics include the comparison between autotrophic and heterotrophic respiration, temporal variation and non-linear responses, and the complexity of changes in the environment. The meeting featured several researchers including Vidya Suseela of Purdue University in the U.S.

•The rich ecology of tropical forests is intimately tied to their moisture status. Multi-site syntheses can provide a macro-scale view of these linkages and their susceptibility to changing climates. Here, we report pan-tropical and regional-scale analyses of tree vulnerability to drought. •We assembled available data on tropical forest tree stem mortality before, during, and after recent drought events, from 119 monitoring plots in 10 countries concentrated in Amazonia and Borneo. •In most sites, larger trees are disproportionately at risk. At least within Amazonia, low wood density trees are also at greater risk of drought-associated mortality, independent of size. For comparable drought intensities, trees in Borneo are more vulnerable than trees in the Amazon. There is some evidence for lagged impacts of drought, with mortality rates remaining elevated 2 yr after the meteorological event is over. •These findings indicate that repeated droughts would shift the functional composition of tropical forests toward smaller, denser-wooded trees. At very high drought intensities, the linear relationship between tree mortality and moisture stress apparently breaks down, suggesting the existence of moisture stress thresholds beyond which some tropical forests would suffer catastrophic tree mortality. [ABSTRACT FROM AUTHOR]

Agricultural weeds evolve in response to crop cultivation. Nevertheless, the central importance of evolutionary ecology for understanding weed invasion, persistence and management in agroecosystems is not widely acknowledged. This paper calls for more evolutionarily-enlightened weed management, in which management principles are informed by evolutionary biology to prevent or minimize weed adaptation and spread. As a first step, a greater knowledge of the extent, structure and significance of genetic variation within and between weed populations is required to fully assess the potential for weed adaptation. The evolution of resistance to herbicides is a classic example of weed adaptation. Even here, most research focuses on describing the physiological and molecular basis of resistance, rather than conducting studies to better understand the evolutionary dynamics of selection for resistance. We suggest approaches to increase the application of evolutionary-thinking to herbicide resistance research. Weed population dynamics models are increasingly important tools in weed management, yet these models often ignore intrapopulation and interpopulation variability, neglecting the potential for weed adaptation in response to management. Future agricultural weed management can benefit from greater integration of ecological and evolutionary principles to predict the long-term responses of weed populations to changing weed management, agricultural environments and global climate. [ABSTRACT FROM AUTHOR]

• This paper presents the results of 2 yr of CO2 flux measurements on grassland communities of varying species richness, exposed to either the current or a warmer climate. • We grew experimental plant communities containing one, three or nine grassland species in 12 sunlit, climate-controlled chambers. Half of these chambers were exposed to ambient air temperatures, while the other half were warmed by 3°C. Equal amounts of water were added to heated and unheated communities, implying drier soils if warming increased evapotranspiration. Three main CO2 fluxes (gross photosynthesis, above-ground and below-ground respiration) were measured multiple times per year and reconstructed hourly or half-hourly by relating them to their most important environmental driver. • While CO2 outputs through respiration were largely unchanged under warming, CO2 inputs through photosynthesis were lowered, especially in summer, when heat and drought stress were higher. Above-ground CO2 fluxes were significantly increased in multispecies communities, as more complementary resource use stimulated productivity. Finally, effects of warming appeared to be smallest in monocultures. • This study shows that in a future warmer climate the CO2 sink capacity of temperate grasslands could decline, and that such adverse effects are not likely to be mitigated by efforts to maintain or increase species richness. [ABSTRACT FROM AUTHOR]

Presents a study on the use of leaf form to reconstruct climates of the past. Background on the leaf margin analysis; Important elements in determining leaf form; Globally consistent patterns shown by leaf form and climate relationships.

Summary: To what degree plant ecosystems thermoregulate their canopy temperature (Tc) is critical to assess ecosystems' metabolisms and resilience with climate change, but remains controversial, with opinions from no to moderate thermoregulation capability.With global datasets of Tc, air temperature (Ta), and other environmental and biotic variables from FLUXNET and satellites, we tested the 'limited homeothermy' hypothesis (indicated by Tc & Ta regression slope < 1 or Tc < Ta around midday) across global extratropics, including temporal and spatial dimensions.Across daily to weekly and monthly timescales, over 80% of sites/ecosystems have slopes ≥1 or Tc > Ta around midday, rejecting the above hypothesis. For those sites unsupporting the hypothesis, their Tc–Ta difference (ΔT) exhibits considerable seasonality that shows negative, partial correlations with leaf area index, implying a certain degree of thermoregulation capability. Spatially, site‐mean ΔT exhibits larger variations than the slope indicator, suggesting ΔT is a more sensitive indicator for detecting thermoregulatory differences across biomes. Furthermore, this large spatial‐wide ΔT variation (0–6°C) is primarily explained by environmental variables (38%) and secondarily by biotic factors (15%).These results demonstrate diverse thermoregulation patterns across global extratropics, with most ecosystems negating the 'limited homeothermy' hypothesis, but their thermoregulation still occurs, implying that slope < 1 or Tc < Ta are not necessary conditions for plant thermoregulation. See also the Commentary on this article by Drake, 238: 921–923. [ABSTRACT FROM AUTHOR]

Summary: A warming climate coupled with reductions in water availability and rising salinity are increasingly affecting rice (Oryza sativa) yields. Elevated temperatures combined with vapour pressure deficit (VPD) rises are causing stomatal closure, further reducing plant productivity and cooling. It is unclear what stomatal size (SS) and stomatal density (SD) will best suit all these environmental extremes.To understand how stomatal differences contribute to rice abiotic stress resilience, we screened the stomatal characteristics of 72 traditionally bred varieties. We found significant variation in SS, SD and calculated anatomical maximal stomatal conductance (gsmax) but did not identify any varieties with SD and gsmax as low as transgenic OsEPF1oe plants.Traditionally bred varieties with high SD and small SS (resulting in higher gsmax) typically had lower biomasses, and these plants were more resilient to drought than low SD and large SS plants, which were physically larger. None of the varieties assessed were as resilient to drought or salinity as low SD OsEPF1oe transgenic plants. High SD and small SS rice displayed faster stomatal closure during increasing temperature and VPD, but photosynthesis and plant cooling were reduced.Compromises will be required when choosing rice SS and SD to tackle multiple future environmental stresses. [ABSTRACT FROM AUTHOR]

Summary: Intrinsic water‐use efficiency (iWUE), a key index for carbon and water balance, has been widely estimated from tree‐ring δ13C at annual resolution, but rarely at high‐resolution intraseasonal scale.We estimated high‐resolution iWUE from laser‐ablation δ13C analysis of tree‐rings (iWUEiso) and compared it with iWUE derived from gas exchange (iWUEgas) and eddy covariance (iWUEEC) data for two Pinus sylvestris forests from 2002 to 2019.By carefully timing iWUEiso via modeled tree‐ring growth, iWUEiso aligned well with iWUEgas and iWUEEC at intraseasonal scale. However, year‐to‐year patterns of iWUEgas, iWUEiso, and iWUEEC were different, possibly due to distinct environmental drivers on iWUE across leaf, tree, and ecosystem scales. We quantified the modification of iWUEiso by postphotosynthetic δ13C enrichment from leaf sucrose to tree rings and by nonexplicit inclusion of mesophyll and photorespiration terms in photosynthetic discrimination model, which resulted in overestimation of iWUEiso by up to 11% and 14%, respectively.We thus extended the application of tree‐ring δ13C for iWUE estimates to high‐resolution intraseasonal scale. The comparison of iWUEgas, iWUEiso, and iWUEEC provides important insights into physiological acclimation of trees across leaf, tree, and ecosystem scales under climate change and improves the upscaling of ecological models. [ABSTRACT FROM AUTHOR]

This Virtual Issue "The biology of wood", highlights the central role of wood biology in basic plant science, as well as critical ecological, environmental, economic and societal issues. It seems as though the plastid and mitochondrial carbon metabolism pathway genes show a coordinated expression with their nuclear gene counterparts, and with specific stages of wood development. The functional characterization of a poplar Class I KNOX gene, I KNAT2/6b i , concluded that this gene is important for the regulation of cell differentiation, in part through its influence on the expression of NAC transcription factors (Zhao I et al i ., [14], in this issue of I New Phytologist i , pp. 1531-1543). Integration of these data showed an enrichment of specific epigenetic markers with genes expressed during wood formation, and together represent an important advancement in our global understanding of gene regulation during wood formation. [Extracted from the article]

Because of their prominent role in the global carbon balance and their possible carbon sequestration, trees are very important organisms in relation to global climatic changes. Knowledge of these processes is the key to understanding the functioning of the whole forest ecosystem which can be modelled and predicted based on the physiological process information. This paper reviews the major methods and techniques used to examine the likely effects of elevated CO2 on woody plants, as well as the major physiological responses of trees to elevated CO2. The available exposure techniques and approaches are described. An overview table with all relevant literature data over the period 1989-93 summarizes the percent changes in biomass. root/shoot ratio, photosynthesis, leaf area and water use efficiency under elevated CO2. Interaction between growth, photosynthesis and nutrition is discussed with a special emphasis on downward regulation of photosynthesis. The stimulation or reduction found in the respiratory processes of woody plants are reviewed, as well as the effect of elevated CO2 on stomatal density, conductance and water use efficiency. Changes in plant quality and their consequences are examined. Changes in underground processes under elevated CO2 are especially emphasized and related to the functioning of the ecosystem. Some directions for future research arc put forward. [ABSTRACT FROM AUTHOR]

An interview with Mark G. Tjoelker, Professor at the Hawkesbury Institute for the Environment at Western Sydney University is presented. He was motivated to do research in the human-driven environmental change on ecosystem. Tjoelker talks about his favorite plant which is the Pinus banksiana species, a jack pine that is distributed throughout North America.

Summary: Optimal stomatal theory predicts that stomata operate to maximise photosynthesis (Anet) and minimise transpirational water loss to achieve optimal intrinsic water‐use efficiency (iWUE). We tested whether this theory can predict stomatal responses to elevated atmospheric CO2 (eCO2), and whether it can capture differences in responsiveness among woody plant functional types (PFTs).We conducted a meta‐analysis of tree studies of the effect of eCO2 on iWUE and its components Anet and stomatal conductance (gs). We compared three PFTs, using the unified stomatal optimisation (USO) model to account for confounding effects of leaf–air vapour pressure difference (D). We expected smaller gs, but greater Anet, responses to eCO2 in gymnosperms compared with angiosperm PFTs.We found that iWUE increased in proportion to increasing eCO2 in all PFTs, and that increases in Anet had stronger effects than reductions in gs. The USO model correctly captured stomatal behaviour with eCO2 across most datasets. The chief difference among PFTs was a lower stomatal slope parameter (g1) for the gymnosperm, compared with angiosperm, species.Land surface models can use the USO model to describe stomatal behaviour under changing atmospheric CO2 conditions. [ABSTRACT FROM AUTHOR]

Summary: Plants produce a wide diversity of metabolites. Yet, our understanding of how shifts in plant metabolites as a response to climate change feedback on ecosystem processes remains scarce. Here, we test to what extent climate warming shifts the seasonality of metabolites produced by Sphagnum mosses, and what are the consequences of these shifts for peatland C uptake.We used a reciprocal transplant experiment along a climate gradient in Europe to simulate climate change. We evaluated the responses of primary and secondary metabolites in five Sphagnum species and related their responses to gross ecosystem productivity (GEP).When transplanted to a warmer climate, Sphagnum species showed consistent responses to warming, with an upregulation of either their primary or secondary metabolite according to seasons. Moreover, these shifts were correlated to changes in GEP, especially in spring and autumn.Our results indicate that the Sphagnum metabolome is very plastic and sensitive to warming. We also show that warming‐induced changes in the seasonality of Sphagnum metabolites have consequences on peatland GEP. Our findings demonstrate the capacity for plant metabolic plasticity to impact ecosystem C processes and reveal a further mechanism through which Sphagnum could shape peatland responses to climate change. [ABSTRACT FROM AUTHOR]

Summary: The considerable drought tolerance of wild cereal crop progenitors has diminished during domestication in the pursuit of higher productivity. Regaining this trait in cereal crops is essential for global food security but requires novel genetic insight.Here, we assessed the molecular evidence for natural variation of drought tolerance in wild barley (Hordeum spontaneum), wild emmer wheat (Triticum dicoccoides), and Brachypodium species collected from dry and moist habitats at Evolution Canyon, Israel (ECI).We report that prevailing moist vs dry conditions have differentially shaped the stomatal and photosynthetic traits of these wild cereals in their respective habitats. We present the genomic and transcriptomic evidence accounting for differences, including co‐expression gene modules, correlated with physiological traits, and selective sweeps, driven by the xeric site conditions on the African Slope (AS) at ECI. Co‐expression gene module 'circadian rhythm' was linked to significant drought‐induced delay in flowering time in Brachypodium stacei genotypes. African Slope‐specific differentially expressed genes are important in barley drought tolerance, verified by silencing Disease‐Related Nonspecific Lipid Transfer 1 (DRN1), Nonphotochemical Quenching 4 (NPQ4), and Brassinosteroid‐Responsive Ring‐H1 (BRH1).Our results provide new genetic information for the breeding of resilient wheat and barley in a changing global climate with increasingly frequent drought events. [ABSTRACT FROM AUTHOR]

No gas source, no problem: proximity to pre-existing embolism and segmentation affect embolism spreading in angiosperm xylem by gas diffusion. However, our micro-CT images showed heterogeneity of embolism along the branch sample under given dehydration stages (See Methods S2), and the embolism level did not consistently decrease from the cut end to the distal end (Fig. However, vessels in proximity to air sources (e.g. pre-existing embolism, cut-open vessels) are reported to be more prone to embolism (Brodersen I et al i ., [2]; Guan I et al i ., [6]). Keywords: climate change; drought resistance; embolism; micro-CT; plant hydraulics; vulnerability curves EN climate change drought resistance embolism micro-CT plant hydraulics vulnerability curves 384 391 8 12/22/22 20230115 NES 230115 A reply to Brum et al. (2023) 'Reconciling discrepancies in measurements of vulnerability to... The integrity of the plant water transport system is crucial for plant performance and survival (Rowland I et al i ., [14]). [Extracted from the article]

Summary: Vast population movements induced by recurrent climatic cycles have shaped the genetic structure of plant species. During glacial periods species were confined to low‐latitude refugia from which they recolonized higher latitudes as the climate improved. This multipronged recolonization led to many lineages that later met and formed large contact zones.We utilize genomic data from 5000 Picea abies trees to test for the presence of natural selection during recolonization and establishment of a contact zone in Scandinavia.Scandinavian P. abies is today made up of a southern genetic cluster originating from the Baltics, and a northern one originating from Northern Russia. The contact zone delineating them closely matches the limit between two major climatic regions. We show that natural selection contributed to its establishment and maintenance. First, an isolation‐with‐migration model with genome‐wide linked selection fits the data better than a purely neutral one. Second, many loci show signatures of selection or are associated with environmental variables. These loci, regrouped in clusters on chromosomes, are often related to phenology.Altogether, our results illustrate how climatic cycles, recolonization and selection can establish strong local adaptation along contact zones and affect the genetic architecture of adaptive traits. [ABSTRACT FROM AUTHOR]

An interview with biologist and ecologist Teresa Rosas is presented. Topics covered include the inspiration behind her interest in plant science, reasons for her decision to pursue a career in research, why the olive tree is her favorite plant and recent research on plant hydraulic framework that have encouraged her daily research.

The article presents an interview with plant scientist Belinda E. Medlyn. Topics discussed include her inspirations behind choosing plant science as a career, her research which interfaces between experiments and models to use experimental data to develop evidence-based models of ecosystem function, and her works to predict drought mortality risk for Australian tree species.

Summary: Shifts in flowering phenology are important indicators of climate change. However, the role of precipitation in driving phenology is far less understood compared with other environmental cues, such as temperature.We use a precipitation reduction gradient to test the direction and magnitude of effects on reproductive phenology and reproduction across 11 plant species in a temperate grassland, a moisture‐limited ecosystem. Our experiment was conducted in a single, relatively wet year. We examine the effects of precipitation for species, functional types, and the community.Our results provide evidence that reduced precipitation shifts phenology, alters flower and fruit production, and that the magnitude and direction of the responses depend on functional type and species. For example, early‐blooming species shift toward earlier flowering, whereas later‐blooming species shift toward later flowering. Because of opposing species‐level shifts, there is no overall shift in community‐level phenology.This study provides experimental evidence that changes in rainfall can drive phenological shifts. Our results additionally highlight the importance of understanding how plant functional types govern responses to changing climate conditions, which is relevant for forecasting phenology and community‐level changes. Specifically, the implications of divergent phenological shifts between early‑ and late‐flowering species include resource scarcity for pollinators and seed dispersers and new temporal windows for invasion. [ABSTRACT FROM AUTHOR]

Summary: Genetic signature of climate adaptation has been widely recognized across the genome of many organisms; however, the eco‐physiological basis for linking genomic polymorphisms with local adaptations remains largely unexplored.Using a panel of 218 world‐wide Arabidopsis accessions, we characterized the natural variation in root suberization by quantifying 16 suberin monomers. We explored the associations between suberization traits and 126 climate variables. We conducted genome‐wide association analysis and integrated previous genotype–environment association (GEA) to identify the genetic bases underlying suberization variation and their involvements in climate adaptation.Root suberin content displays extensive variation across Arabidopsis populations and significantly correlates with local moisture gradients and soil characteristics. Specifically, enhanced suberization is associated with drier environments, higher soil cation‐exchange capacity, and lower soil pH; higher proportional levels of very‐long‐chain suberin is negatively correlated with moisture availability, lower soil gravel content, and higher soil silt fraction. We identified 94 putative causal loci and experimentally proved that GPAT6 is involved in C16 suberin biosynthesis. Highly significant associations between the putative genes and environmental variables were observed.Roots appear highly responsive to environmental heterogeneity via regulation of suberization, especially the suberin composition. The patterns of suberization–environment correlation and the suberin‐related GEA fit the expectations of local adaptation for the polygenic suberization trait. [ABSTRACT FROM AUTHOR]

Summary: Climate change and pathogen outbreaks are the two major causes of decline in Mediterranean holm oak trees (Quercus ilex L. subsp. ballota (Desf.) Samp.). Crown‐level changes in response to these stressful conditions have been widely documented but the responses of the root systems remain unexplored. The effects of environmental stress over roots and its potential role during the declining process need to be evaluated.We aimed to study how key morphological and architectural root parameters and nonstructural carbohydrates of roots are affected along a holm oak health gradient (i.e. within healthy, susceptible and declining trees).Holm oaks with different health statuses had different soil resource‐uptake strategies. While healthy and susceptible trees showed a conservative resource‐uptake strategy independently of soil nutrient availability, declining trees optimized soil resource acquisition by increasing the phenotypic plasticity of their fine root system.This increase in fine root phenotypic plasticity in declining holm oaks represents an energy‐consuming strategy promoted to cope with the stress and at the expense of foliage maintenance. Our study describes a potential feedback loop resulting from strong unprecedented belowground stress that ultimately may lead to poor adaptation and tree death in the Spanish dehesa. [ABSTRACT FROM AUTHOR]

Summary: The length of time a flower remains open and functional – floral longevity – governs important reproductive processes influencing pollination and mating and varies considerably among angiosperm species. However, little is known about large‐scale biogeographic patterns and the correlates of floral longevity.Using published data on floral longevity from 818 angiosperm species in 134 families and 472 locations world‐wide, we present the first global quantification of the latitudinal pattern of floral longevity and the relationships between floral longevity and a range of biotic and abiotic factors.Floral longevity exhibited a significant phylogenetic signal and was longer at higher latitudes in both northern and southern hemispheres, even after accounting for elevation. This latitudinal variation was associated with several biotic and abiotic variables. The mean temperature of the flowering season had the highest predictive power for floral longevity, followed by pollen number per flower. Surprisingly, compatibility status, flower size, pollination mode, and growth form had no significant effects on flower longevity.Our results suggest that physiological processes associated with floral maintenance play a key role in explaining latitudinal variation in floral longevity across global ecosystems, with potential implications for floral longevity under global climate change and species distributions. [ABSTRACT FROM AUTHOR]

This article is a Commentary on Guo et al. (2023), 238: 1004–1018. [ABSTRACT FROM AUTHOR]

Summary: Heat waves occurring during droughts can have a devastating impact on yield, especially if they happen during the flowering and seed set stages of the crop cycle. Global warming and climate change are driving an alarming increase in the frequency and intensity of combined drought and heat stress episodes, critically threatening global food security.Because high temperature is detrimental to reproductive processes, essential for plant yield, we measured the inner temperature, transpiration, sepal stomatal aperture, hormone concentrations and transcriptomic response of closed soybean flowers developing on plants subjected to a combination of drought and heat stress.Here, we report that, during a combination of drought and heat stress, soybean plants prioritize transpiration through flowers over transpiration through leaves by opening their flower stomata, while keeping their leaf stomata closed. This acclimation strategy, termed 'differential transpiration', lowers flower inner temperature by about 2–3°C, protecting reproductive processes at the expense of vegetative tissues.Manipulating stomatal regulation, stomatal size and/or stomatal density of flowers could serve as a viable strategy to enhance the yield of different crops and mitigate some of the current and future impacts of global warming and climate change on agriculture. [ABSTRACT FROM AUTHOR]

Summary: Today plants often flower earlier due to climate warming. Herbarium specimens are excellent witnesses of such long‐term changes. However, the magnitude of phenological shifts may vary geographically, and the data are often clustered. Therefore, large‐scale analyses of herbarium data are prone to pseudoreplication and geographical biases.We studied over 6000 herbarium specimens of 20 spring‐flowering forest understory herbs from Europe to understand how their phenology had changed during the last century. We estimated phenology trends with or without taking spatial autocorrelation into account.On average plants now flowered over 6 d earlier than at the beginning of the last century. These changes were strongly associated with warmer spring temperatures. Flowering time advanced 3.6 d per 1°C warming. Spatial modelling showed that, in some parts of Europe, plants flowered earlier or later than expected. Without accounting for this, the estimates of phenological shifts were biased and model fits were poor.Our study indicates that forest wildflowers in Europe strongly advanced their phenology in response to climate change. However, these phenological shifts differ geographically. This shows that it is crucial to combine the analysis of herbarium data with spatial modelling when testing for long‐term phenology trends across large spatial scales. [ABSTRACT FROM AUTHOR]

Summary: Climate change is increasing global temperatures and the frequency and severity of droughts in many regions. These anthropogenic stresses pose a significant threat to plant performance and crop production. The plant‐associated microbiome modulates the impacts of biotic and abiotic stresses on plant fitness. However, climate change‐induced alteration in composition and activities of plant microbiomes can affect host functions. Here, we highlight recent advancements in our understanding of the impact of climate change (warming and drought) on plant–microbiome interactions and on their ecological functions from genome to ecosystem scales. We identify knowledge gaps, propose new concepts and make recommendations for future research directions. It is proposed that in the short term (years to decades), the adaptation of plants to climate change is mainly driven by the plant microbiome, whereas in the long term (century to millennia), the adaptation of plants will be driven equally by eco‐evolutionary interactions between the plant microbiome and its host. A better understanding of the response of the plant and its microbiome interactions to climate change and the ways in which microbiomes can mitigate the negative impacts will better inform predictions of climate change impacts on primary productivity and aid in developing management and policy tools to improve the resilience of plant systems. [ABSTRACT FROM AUTHOR]

Summary: Plants form complex interaction networks with diverse microbiomes in the environment, and the intricate interplay between plants and their associated microbiomes can greatly influence ecosystem processes and functions. The phyllosphere, the aerial part of the plant, provides a unique habitat for diverse microbes, and in return the phyllosphere microbiome greatly affects plant performance. As an open system, the phyllosphere is subjected to environmental perturbations, including global change, which will impact the crosstalk between plants and their microbiomes. In this review, we aim to provide a synthesis of current knowledge of the complex interactions between plants and the phyllosphere microbiome under global changes and to identify future priority areas of research on this topic. [ABSTRACT FROM AUTHOR]

Summary: Bacterial communities form the basis of biogeochemical processes and determine plant growth and health. Mosses harbour diverse bacterial communities that are involved in nitrogen fixation and carbon cycling. Global climate change is causing changes in aboveground plant biomass and shifting species composition in the Arctic, but little is known about the response of moss microbiomes in these environments.Here, we studied the total and potentially active bacterial communities associated with Racomitrium lanuginosum in response to a 20‐yr in situ warming in an Icelandic heathland. We evaluated the effect of warming and warming‐induced shrub expansion on the moss bacterial community composition and diversity, and nifH gene abundance.Warming changed both the total and the potentially active bacterial community structure, while litter abundance only affected the total bacterial community structure. The abundance of nifH genes was negatively affected by litter abundance. We also found shifts in the potentially nitrogen‐fixing community, with Nostoc decreasing and noncyanobacterial diazotrophs increasing in relative abundance.Our data suggest that the moss microbial community and potentially nitrogen fixing taxa will be sensitive to future warming, partly via changes in litter and shrub abundance. [ABSTRACT FROM AUTHOR]

Summary: Human activity is causing a global change in plant environment that includes a significant increase in the number and intensity of different stress factors. These include combinations of multiple abiotic and biotic stressors that simultaneously or sequentially impact plants and microbiomes, causing a significant decrease in plant growth, yield and overall health. It was recently found that with the increasing number and complexity of stressors simultaneously impacting a plant, plant growth and survival decline dramatically, even if the level of each individual stress, involved in such 'multifactorial stress combination', is low enough not to have a significant effect. Here we highlight this new concept of multifactorial stress combination and discuss its importance for our efforts to develop climate change‐resilient crops. [ABSTRACT FROM AUTHOR]

Summary: Plants have evolved to time their leafing, flowering and fruiting in appropriate seasons for growth, reproduction and resting. As a consequence of their adaptation to geographically different environments, there is a rich diversity in plant phenology from temperate and tropical climates. Recent progress in genetic and molecular studies will provide numerous opportunities to study the genetic basis of phenological traits and the history of adaptation of phenological traits to seasonal and aseasonal environments. Integrating molecular data with long‐term phenology and climate data into predictive models will be a powerful tool to forecast future phenological changes in the face of global environmental change. Here, we review the cross‐scale approach from genes to plant communities from three aspects: the latitudinal gradient of plant phenology at the community level, the environmental and genetic factors underlying the diversity of plant phenology, and an integrated approach to forecast future plant phenology based on genetically informed knowledge. Synthesizing the latest knowledge about plant phenology from molecular, ecological and mathematical perspectives will help us understand how natural selection can lead to the further evolution of the gene regulatory mechanisms in phenological traits in future forest ecosystems. [ABSTRACT FROM AUTHOR]

Summary: Primary production in the Southern Ocean is dominated by diatom‐rich phytoplankton assemblages, whose individual physiological characteristics and community composition are strongly shaped by the environment, yet knowledge on how diatoms allocate cellular energy in response to ocean acidification (OA) is limited. Understanding such changes in allocation is integral to determining the nutritional quality of diatoms and the subsequent impacts on the trophic transfer of energy and nutrients.Using synchrotron‐based Fourier transform infrared microspectroscopy, we analysed the macromolecular content of selected individual diatom taxa from a natural Antarctic phytoplankton community exposed to a gradient of fCO2 levels (288–1263 µatm).Strong species‐specific differences in macromolecular partitioning were observed under OA. Large taxa showed preferential energy allocation towards proteins, while smaller taxa increased both lipid and protein stores at high fCO2.If these changes are representative of future Antarctic diatom physiology, we may expect a shift away from lipid‐rich large diatoms towards a community dominated by smaller taxa, but with higher lipid and protein stores than their present‐day contemporaries, a response that could have cascading effects on food web dynamics in the Antarctic marine ecosystem. [ABSTRACT FROM AUTHOR]

This article is a Commentary on Oduor (2022), 233: 983–994. [ABSTRACT FROM AUTHOR]

Summary: A group of MADS transcription factors (TFs) are believed to control temperature‐mediated bud dormancy. These TFs, called DORMANCY‐ASSOCIATED MADS‐BOX (DAM), are encoded by genes similar to SHORT VEGETATIVE PHASE (SVP) from Arabidopsis. MADS proteins form transcriptional complexes whose combinatory composition defines their molecular function. However, how MADS multimeric complexes control the dormancy cycle in trees is unclear.Apple MdDAM and other dormancy‐related MADS proteins form complexes with MdSVPa, which is essential for the ability of transcriptional complexes to bind to DNA. Sequential DNA‐affinity purification sequencing (seq‐DAP‐seq) was performed to identify the genome‐wide binding sites of apple MADS TF complexes. Target genes associated with the binding sites were identified by combining seq‐DAP‐seq data with transcriptomics datasets obtained using a glucocorticoid receptor fusion system, and RNA‐seq data related to apple dormancy.We describe a gene regulatory network (GRN) formed by MdSVPa‐containing complexes, which regulate the dormancy cycle in response to environmental cues and hormonal signaling pathways. Additionally, novel molecular evidence regarding the evolutionary functional segregation between DAM and SVP proteins in the Rosaceae is presented.MdSVPa sequentially forms complexes with the MADS TFs that predominate at each dormancy phase, altering its DNA‐binding specificity and, therefore, the transcriptional regulation of its target genes. [ABSTRACT FROM AUTHOR]

Information about several papers discussed at the 29th New Phytologist Symposium: Stomata in Manchester, England in July 2012 on the global impact of stomatic pores and guard cells is presented. Topics include stomatal development and evolution, climate models and improved crop production. Its logo is also provided which shows the role of such cells in regulating worldwide issues such as climate change and breeding of sustainable crop.

Summary: The frequency and severity of heatwave events are increasing, exposing species to conditions beyond their physiological limits. Species respond to heatwaves in different ways, however it remains unclear if plants have the adaptive capacity to successfully respond to hotter and more frequent heatwaves.We exposed eight tree populations from two climate regions grown under cool and warm temperatures to repeated heatwave events of moderate (40°C) and extreme (46°C) severity to assess adaptive capacity to heatwaves.Leaf damage and maximum quantum efficiency of photosystem II (Fv/Fm) were significantly impacted by heatwave severity and growth temperatures, respectively; populations from a warm‐origin avoided damage under moderate heatwaves compared to those from a cool‐origin, indicating a degree of local adaptation. We found that plasticity to heatwave severity and repeated heatwaves contributed to enhanced thermal tolerance and lower leaf temperatures, leading to greater thermal safety margins (thermal tolerance minus leaf temperature) in a second heatwave.Notably, while we show that adaptation and physiological plasticity are important factors affecting plant adaptive capacity to thermal stress, plasticity of thermal tolerances and thermal safety margins provides the opportunity for trees to persist among fluctuating heatwave exposures. [ABSTRACT FROM AUTHOR]

Summary: Nocturnal stomatal conductance (gsn) represents a significant source of water loss, with implications for metabolism, thermal regulation and water‐use efficiency. With increasing nocturnal temperatures due to climate change, it is vital to identify and understand variation in the magnitude and responses of gsn in major crops.We assessed interspecific variation in gsn and daytime stomatal conductance (gs) in a wild relative and modern spring wheat genotype. To investigate intraspecific variation, we grew six modern wheat genotypes and two landraces under well watered, simulated field conditions.For the diurnal data, higher gsn in the wild relative was associated with significantly lower nocturnal respiration and higher daytime CO2 assimilation while both species exhibited declines in gsn post‐dusk and pre‐dawn. Lifetime gsn achieved rates of 5.7–18.9% of gs. Magnitude of gsn was genotype specific 'and positively correlated with gs. gsn and gs were significantly higher on the adaxial surface. No relationship was determined between harvest characteristics, stomatal morphology and gsn, while cuticular conductance was genotype specific. Finally, for the majority of genotypes, gsn declined with age.Here we present the discovery that variation in gsn occurs across developmental, morphological and temporal scales in nonstressed wheat, presenting opportunities for exploiting intrinsic variation under heat or water stressed conditions. [ABSTRACT FROM AUTHOR]

Summary: Spring phenology is advancing with warming but late spring freezes may not advance at the same rate, potentially leading to an increase in freezes after trees initiate budburst. Research suggests warming winters may delay budburst through reduced chilling, which may cause plants to leafout more slowly, thus decreasing spring freeze tolerance.Here, we assessed the effects of late spring freezes and reduced over‐winter chilling on sapling phenology, growth and tissue traits, across eight temperate tree and shrub species in a laboratory experiment.We found that spring freezes delayed leafout – extending the period of greatest risk for freeze damage – increased damage to the shoot apical meristem, and decreased leaf toughness and leaf thickness. Longer chilling accelerated budburst and leafout, even under spring freeze conditions. Thus, chilling compensated for the adverse effects of late spring freezes on phenology. Despite the effects of spring freezes and chilling on phenology, we did not see any major reordering in the sequence of species leafout.Our results suggest climate change may impact forest communities not through temporal reassembly, but rather through impacts on phenology and growth from the coupled effects of late spring freezes and decreased over‐winter chilling under climate change. [ABSTRACT FROM AUTHOR]

Summary: Botanical gardens make unique contributions to climate change research, conservation, and public engagement. They host unique resources, including diverse collections of plant species growing in natural conditions, historical records, and expert staff, and attract large numbers of visitors and volunteers. Networks of botanical gardens spanning biomes and continents can expand the value of these resources. Over the past decade, research at botanical gardens has advanced our understanding of climate change impacts on plant phenology, physiology, anatomy, and conservation. For example, researchers have utilized botanical garden networks to assess anatomical and functional traits associated with phenological responses to climate change. New methods have enhanced the pace and impact of this research, including phylogenetic and comparative methods, and online databases of herbarium specimens and photographs that allow studies to expand geographically, temporally, and taxonomically in scope. Botanical gardens have grown their community and citizen science programs, informing the public about climate change and monitoring plants more intensively than is possible with garden staff alone. Despite these advances, botanical gardens are still underutilized in climate change research. To address this, we review recent progress and describe promising future directions for research and public engagement at botanical gardens. [ABSTRACT FROM AUTHOR]

Summary: Knowledge regarding mechanisms moderating methane (CH4) sink/source behaviour along the soil–tree stem–atmosphere continuum remains incomplete. Here, we applied stable isotope analysis (δ13C‐CH4) to gain insights into axial CH4 transport and oxidation in two globally distributed subtropical lowland species (Melaleuca quinquenervia and Casuarina glauca).We found consistent trends in CH4 flux (decreasing with height) and δ13C‐CH4 enrichment (increasing with height) in relation to stem height from ground. The average lower tree stem δ13C‐CH4 (0–40 cm) of Melaleuca and Casuarina (−53.96‰ and −65.89‰) were similar to adjacent flooded soil CH4 ebullition (−52.87‰ and −62.98‰), suggesting that stem CH4 is derived mainly by soil sources. Upper stems (81–200 cm) displayed distinct δ13C‐CH4 enrichment (Melaleuca −44.6‰ and Casuarina −46.5‰, respectively).Coupled 3D‐photogrammetry with novel 3D‐stem measurements revealed distinct hotspots of CH4 flux and isotopic fractionation on Melaleuca, which were likely due to bark anomalies in which preferential pathways of gas efflux were enhanced. Diel experiments revealed greater δ13C‐CH4 enrichment and higher oxidation rates in the afternoon, compared with the morning.Overall, we estimated that c. 33% of the methane was oxidised between lower and upper stems during axial transport, therefore potentially representing a globally significant, yet previously unaccounted for, methane sink. [ABSTRACT FROM AUTHOR]