American Journal of Botany最新文献

{"title":"Phylogenetic relationships versus environmental impacts on the distribution and traits of Laureae (Lauraceae) species within and outside karst tiankengs","authors":"Yuxin Dai,&nbsp;Yu Song,&nbsp;Jiaojiao Zhang,&nbsp;Bing Zhao,&nbsp;Liwen Li,&nbsp;Zhenyang Huang,&nbsp;Hao Yang","doi":"10.1002/ajb2.70032","DOIUrl":"10.1002/ajb2.70032","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>A karst tiankeng, a unique sinkhole-like terrain with a rare and distinctive habitat, is often likened to an isolated island because of its limited contact with the external environment. This distinctive landscape potentially shapes the evolution and distribution of the associated plant species. However, the relative contributions of environmental impacts versus phylogenetic relationships in shaping plant adaptations to the tiankeng environment remain unclear. We analyzed trait divergence within Laureae, a dominant group in a tiankeng forest, to discern whether trait variations among Laureae populations within and outside the tiankeng were shaped predominantly by environmental influences or phylogenetic heritage.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We reconstructed a phylogenetic tree for Laureae within and beyond the Baise Tiankengs using plastid genomes to estimate dispersal times, trace ancestral distributions, and model distributional shifts under various climatic scenarios. We also compared leaf and fruit traits of plants within and outside the tiankeng.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The uplift of the Qinghai-Tibet Plateau affected the climate in South China, shaping Laureae traits. A discernible phylogenetic signal indicated environmental factors significantly drive trait variations in Laureae in the tiankeng. A markedly smaller leaf length/width ratio endows the Laureae populations in the tiankeng with enhanced resilience to colder microclimates compared to populations in surrounding areas. Maximum and minimum leaf length/width ratios were also significantly lower in the tiankeng.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>These findings advance our understanding on biodiversity and plant trait divergence inside tiankengs, underscoring the importance of preserving unique habitats and restoring vegetation in these terrains.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 5","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143952550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phylogenetics and population structure of the western North American endemic Pacific Laurasian clade of Isoëtes","authors":"Forrest D. Freund,&nbsp;Daniel Gates,&nbsp;Matthew G. Johnson,&nbsp;Carl J. Rothfels","doi":"10.1002/ajb2.70030","DOIUrl":"https://doi.org/10.1002/ajb2.70030","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p><i>Isoëtes</i> is a genus of small, semi-woody, hydrophilic, heterosporous lycophytes with a cosmopolitan, global distribution. However, local populations tend to be found in narrow, patchy, and highly fragmented mesic to aquatic habitats, many of which are currently under threat. In this study, we sought to uncover how this patchy distribution has affected the evolutionary history of one of the two lineages of <i>Isoëtes</i> found on the West Coast of North America—the Pacific Laurasian clade (PLC).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We used a combination of population genetic and multilocus molecular phylogenetic approaches to infer the relationships among the three described species in this clade and to determine the degree of isolation among the sampled populations.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>We discovered that the populations studied are highly structured and that two of the species, as currently circumscribed, are not monophyletic. Instead, our phylogenetic results suggest that there are at least eight distinct “species-level” clades within the PLC. Of these eight, five appear to have been the result of a rapid radiation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Our results suggest that the existing taxonomy does not reflect the actual diversity in the PLC and warrants further investigation.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143857095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-resolution time-course observations of pollination drop withdrawal in Chinese fir (Cunninghamia lanceolata)","authors":"Houyin Deng,&nbsp;Rong Huang,&nbsp;Ruping Wei,&nbsp;Runhui Wang,&nbsp;Shu Yan,&nbsp;Yuhan Sun,&nbsp;Yun Li,&nbsp;Huiquan Zheng","doi":"10.1002/ajb2.70031","DOIUrl":"https://doi.org/10.1002/ajb2.70031","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Gymnosperms have few mechanisms for shaping the mating pool between the time of pollen reception on a pollination drop (PD) and fertilization. The duration of the PD on the ovule may be one mechanism if it changes depending on relatedness of the pollen source and the recipient. Here, we timed the duration of the PD after pollination with pollen from different clones of the outcrossing conifer <i>Cunninghamia lanceolata</i>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We collected unpollinated strobili from <i>C. lanceolata</i> in the field and grew them hydroponically in a controlled chamber to induce PD production. Using high-resolution imaging, we monitored PD dynamics in real time after selfed, inbred backcross, and outcross pollination. Interparental genetic distances (GD) were determined for each cross using 21 polymorphic microsatellite loci.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The high-resolution imaging revealed that PDs in nonpollinated ovules were exposed for an average of 10.63 ± 1.31 h, whereas PDs in ovules after outcrossing and selfing were withdrawn within 0.46 ± 0.06 h and 3.43 ± 0.84 h, respectively. The three inbred backcrosses were intermediate between selfing and outcrossing. High-resolution videos further confirmed the withdrawal was rapid and abrupt after outcrossing and slower after most inbred crosses, especially selfing. There was a strong negative correlation between genetic distance and PD withdrawal time (<i>r</i> = −0.92, <i>P</i> &lt; 0.0001), implying a regulatory mechanism sensitive to the degree of relatedness.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>These novel findings suggest that the longevity of the PD is a mechanism for post-pollination mate recognition.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143857014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Community phylogenetics of North American conifers through the lens of fire-adapted traits.","authors":"Daniel F Turck, Aaron M Sparks, Jack Sullivan, David C Tank","doi":"10.1002/ajb2.70029","DOIUrl":"https://doi.org/10.1002/ajb2.70029","url":null,"abstract":"<p><strong>Premise: </strong>In the face of novel fire regimes driven by anthropogenic changes to climate, ignitions, and fuels, understanding the evolution and present distribution of fire-adapted traits is critical. Four common fire adaptations in conifers are thick bark, serotinous cones, seedling grass stage, and resprouting.</p><p><strong>Methods: </strong>We focused on these fire-adapted traits and their abundance in North American conifers within a community phylogenetic context. Using ranges derived from numerous sources, we divided the continent into 20 conifer regions. We assessed regions for species richness, number of fire adaptations, number of taxa with each fire adaptation, and the percent composition of species with fire adaptations. We calculated regional phylogenetic dispersion metrics for each fire adaptation as well.</p><p><strong>Results: </strong>For almost every analysis, a north-south trend was evident and had strong spatial correspondence with fire intensity and frequency metrics of contemporary fire regimes. Species richness and nearly every measure of fire adaptation abundance, increases with decreasing latitude. Northern latitudes also lack resprouting and the grass stage. We identified three fire-prone regions: California, Mexico and Central America, and the Gulf Coast. In terms of community composition, northern and mid-latitude regions trend toward neutral assembly, while southern regions are phylogenetically clustered. In most regions, fire adaptations are phylogenetically clustered, indicating that even in neutrally assembled ecosystems, fire adaptations are restricted to a few clades.</p><p><strong>Conclusions: </strong>Given this information, we advocate tailoring management strategies toward present fire adaptations (or lack thereof), emphasizing strengthening fire resilience in fire-adapted ecosystems and maintaining the integrity of fire refugia.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70029"},"PeriodicalIF":2.4,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143794410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The self-replicating cellular organization of shoot apical meristems","authors":"Étienne Couturier,&nbsp;Paula Llanos,&nbsp;Antoine Lizée,&nbsp;Sébastien Besson,&nbsp;Jacques Dumais","doi":"10.1002/ajb2.70027","DOIUrl":"10.1002/ajb2.70027","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Apical meristems of land plants have played a fundamental role in the evolution of complex shoot architectures. The most common structure of shoot apical meristems in bryophytes, lycophytes, and ferns is characterized by a single apical cell surrounded by a spiral of apical derivatives. Despite the importance of this type of meristem organization, it remains unclear how it is maintained at the apex.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We analyzed the distribution of different meristem organizations within a data set of 205 images of shoot apical meristems representing 91 species of bryophytes, lycophytes, and ferns. In parallel, we developed a mathematical and computational model to determine whether the meristem structural types observed empirically are predicted from Sachs's division rules; namely, cells divide symmetrically while positioning their new wall at a right angle to the parental walls.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>According to our data set, only four meristem structural types are observed in nature, corresponding to apical cells dividing along one, two, three, or four faces. In addition, the prevalence of the structural types in diverse plant lineages correlates with the shape of the meristems on which they are found. Our model based on Sachs's division rules indicates that as much as six meristem structural types are geometrically possible, but only the four types observed empirically are dynamically stable for realistic meristem geometries.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Simple division rules, which we interpret as biophysical constraints on the assembly of the preprophase band, may therefore explain the cellular organization of the shoot apical meristem in three major groups of land plants.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143778753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From the Shenzhen Code to the Madrid Code: New rules and recommendations for naming algae, fungi, and plants","authors":"Nicholas J. Turland","doi":"10.1002/ajb2.70026","DOIUrl":"10.1002/ajb2.70026","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>A universally understood, precise, and stable system of naming organisms is essential for effective scientific communication. The <i>International Code of Nomenclature for algae, fungi, and plants</i>, of which the most recently published edition is the <i>Shenzhen Code</i> of 2018, provides this system for algae, fungi, and plants. This <i>Code</i> is regularly revised at an International Botanical Congress (IBC), usually held every 6 years, most recently in Madrid, Spain, in July 2024. The Madrid IBC amended the <i>Shenzhen Code</i>, and the changes took effect on 27 July 2024, when the closing plenary session of the IBC approved the decisions of the Nomenclature Section. It is important to promptly publicize this information because the new edition of the <i>Code</i> resulting from these amendments, the <i>Madrid Code</i>, will not be published until mid-2025.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>I selected some of the more important of the 433 published proposals to amend the <i>Code</i> at the Madrid IBC. I sourced details from the proposals themselves, the “Synopsis of Proposals” and the “Report of Congress Action” (all published in the journal <i>Taxon</i>) and from the records made during the Nomenclature Section in Madrid.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>For a general botanical audience, I discuss the background, outcomes (acceptance or rejection), and consequences of acceptance of the proposals.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This commentary supplements the technical reports already published and provides an overview of some of the new or amended rules and recommendations in the upcoming <i>Madrid Code</i>.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.70026","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143787521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interaction network of Phoradendron and its hosts and the influence of phylogenetic, geographic, and environmental factors on the probability of interaction","authors":"Eurídice Tinoco-Domínguez,&nbsp;Guadalupe Amancio,&nbsp;Ángel L. Robles-Fernández,&nbsp;Andrés Lira-Noriega","doi":"10.1002/ajb2.70025","DOIUrl":"10.1002/ajb2.70025","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p><i>Phoradendron</i> (Santalaceae) mistletoes consist of approximately 230 hemiparasitic species across the Americas. As obligate hemiparasites, their distribution depends partly on the distribution of their hosts, reflecting a shared evolutionary history.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Using network analysis and statistical modeling, we explored the bipartite host–parasite network, focusing on species organization and the likelihood of hosts sharing a <i>Phoradendron</i> species based on phylogenetic, geographic, and environmental factors.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Our analysis suggests a modular and highly specialized interaction network influenced by evolutionary and biogeographical factors. <i>Phoradendron</i> parasitized hosts in genera from various families and orders, primarily Fabales, Malpighiales, and Sapindales. The network exhibited modularity and connectivity, with hosts sharing a higher likelihood of being parasitized by the same <i>Phoradendron</i> species when they were closer in phylogeny, geography, and environment, while phylogenetic distance emerged as the most relevant determinant. Moreover, we established a link between <i>Phoradendron</i> within-module connectivity and host phylogenetic distance, providing an evolutionary framework for understanding ecological patterns and network connectance.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The network of <i>Phoradendron</i>–host interactions is highly specialized, and the structure of this network depends mainly on the phylogenetic distance of the hosts.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143771049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phylogenomics, historical biogeography, and diversification of leaf traits in the Malagasy-endemic genus Uncarina (Pedaliaceae)","authors":"Jeffrey P. Rose,&nbsp;John G. Zaborsky,&nbsp;Nisa Karimi,&nbsp;Kenneth J. Sytsma","doi":"10.1002/ajb2.70028","DOIUrl":"10.1002/ajb2.70028","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p><i>Uncarina</i> contains 14 species of woody plants endemic to Madagascar. Its occurrence across dryland biomes on the island make it an interesting system to study the diversification of the flora.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Using samples of all species and 512 nuclear loci, we reconstructed phylogenetic trees to examine species relationships and assess their monophyly. We also studied the historical biogeography of the genus and combined leaf trait data derived from SEM photography of trichomes and geometric morphometric analysis of leaf shape to better understand its diversification across dryland biomes.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p><i>Uncarina</i> is monophyletic, and major clades showed a clear biogeographical signal. Leaf traits also corroborated relationships among major clades. Although most species are monophyletic, at least one cryptic species exists. <i>Uncarina</i>, like many arid-adapted plant lineages in Madagascar originated in the Miocene or Pleistocene. Geographic movement has been primarily along a south–north axis, with river basins apparently acting as barriers to gene flow. The evolution of leaf traits corroborated movement from the spiny thicket to the dry forest biome.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>As with Malagasy lemurs and other animals, riverine barriers may have been involved in the diversification of <i>Uncarina</i> and may apply more broadly to epizoochorous angiosperms of Madagascar. Leaf traits suggest either a loss of adaptations to extremely arid, high irradiance environments or a release from herbivores. As is likely needed in other Malagasy lineages, more thorough population-level sampling and specimen collecting is needed to fully understand the taxonomic and morphological diversity in the genus.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.70028","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143771050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extreme cold reduces seedling establishment, but native species appear more susceptible than non-native species","authors":"Peter W. Guiden,&nbsp;Barbara Roca","doi":"10.1002/ajb2.70023","DOIUrl":"10.1002/ajb2.70023","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Extreme-cold events are increasingly recognized as one of the most damaging aspects of climate change in northern temperate ecosystems. However, little data exists describing how native and non-native species may respond to these extreme events, especially as seeds. We used a greenhouse experiment to test how extreme cold reduces seedling establishment in seven woody species common to eastern North America. We hypothesized that the effects of extreme cold depend on provenance (native vs. non-native) and chilling period.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Following chilling periods of 80, 100, or 120 days, seeds experienced a false-spring with temperatures at 15°C for one week; half of the seeds in each dormancy treatment group experienced a two-day extreme-cold event (–13.9°C) while the rest returned to mild winter temperatures (4°C).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Extreme-cold events universally decreased seedling establishment, but non-native species had four times greater survival in the extreme-cold treatment (mean ± s.e.: 0.108 ± 0.024) compared to native species (0.024 ± 0.018). Furthermore, native seeds were increasingly susceptible to extreme-cold damage following a 120-day chilling period, whereas non-native seeds were able to resist extreme cold equally following all chilling periods.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>These results suggest that in eastern North America, cold resistance could be a trait facilitating the success of non-native species. The introduction of non-native species may synergize with climate change to alter community composition, which could have important consequences for forest biodiversity in the Anthropocene.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143717884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Viewing the ecological consequences of synthetic auxin herbicides from the ground up","authors":"Veronica Iriart,&nbsp;Tia-Lynn Ashman","doi":"10.1002/ajb2.70024","DOIUrl":"10.1002/ajb2.70024","url":null,"abstract":"&lt;p&gt;Herbicides, although often less emphasized than other pesticides like insecticides, pose a significant risk to wild plant communities (Iriart et al., &lt;span&gt;2021&lt;/span&gt;). Synthetic auxin or “auxinic” herbicides such as 2,4-D and dicamba have recently surged in use due to the commercialization of transgenic crops tolerant to auxinic herbicides (Johnson et al., &lt;span&gt;2023&lt;/span&gt;). These chemicals act by mimicking the natural phytohormone auxin (indole-3-acetic acid [IAA]) to cause abnormal growth and death in target weeds, but are also linked to a long-standing issue known as herbicide drift, i.e., when herbicide particles (i.e., ~0.1–5% of application rate) move through the atmosphere and away from target sites, that can impair nontarget plants (Johnson et al., &lt;span&gt;2023&lt;/span&gt;). More insidious, however, are the potential consequences beneath the soil. For example, in the symbiotic mutualism between leguminous plants (legumes) and nitrogen-fixing soil rhizobial bacteria (hereafter rhizobia), plants exchange carbohydrates for rhizobia-fixed nitrogen (N) from the atmosphere, contributing to the N cycle and soil fertility (Ahemad and Khan, &lt;span&gt;2013&lt;/span&gt;). However, studies have shown that auxinic herbicides can be especially damaging to legumes (Blanchett et al., &lt;span&gt;2015&lt;/span&gt;; Jones et al., &lt;span&gt;2019&lt;/span&gt;; Iriart et al., &lt;span&gt;2022&lt;/span&gt;), and under certain conditions can directly reduce the growth of free-living rhizobia (Fabra et al., &lt;span&gt;1997&lt;/span&gt;). Moreover, because legume–rhizobia interactions are partly regulated by IAA, symbiotic interactions can be disrupted by synthetic auxins (Ahemad and Khan, &lt;span&gt;2013&lt;/span&gt;; Iriart et al., &lt;span&gt;2024&lt;/span&gt;; Iriart et al., unpublished manuscript)—yet, studies on the effects of auxinic herbicide drift on legume–rhizobia interactions or other phytohormone-regulated symbioses such as the mutualism between a plant and arbuscular mycorrhizal fungi (AMF), are limited. Here, we identify the major gaps in our knowledge of the impacts of low-dose exposures to auxinic herbicides on plant–microbe symbioses in the rhizosphere and the pathways and mechanisms that mediate them. We highlight research areas that will shed light on this issue, including some of the overlooked broader ecological consequences, potentially contributing to the footprint of disruption caused by auxinic herbicides.&lt;/p&gt;&lt;p&gt;Research has largely focused on the direct effects of synthetic auxin exposures on plants and some plant-associated rhizospheric microbes (i.e., Paths 1 and 2, Figure 1; Iriart et al., &lt;span&gt;2021&lt;/span&gt;; Ruuskanen et al., &lt;span&gt;2023&lt;/span&gt;), but rarely on the ecological interactions between them which could likewise be affected via indirect pathways (i.e., Path 3 and 4, Figure 1). For instance, genotypes of plants or of microbes can differ in their physiological or biochemical responses to synthetic auxins (Ahemad and Khan, &lt;span&gt;2013&lt;/span&gt;; Hage-Ahmed et al., &lt;span&gt;2019&lt;/span&gt;; Iriart et al., &lt;span&gt;2022&lt;/","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.70024","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143707918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}