American Journal of Botany最新文献

{"title":"Shaped by context: Evolutionary trajectories of desiccation tolerance in land plants.","authors":"Rose A Marks, R Shawn Abrahams, Jenna T B Ekwealor","doi":"10.1002/ajb2.70180","DOIUrl":"10.1002/ajb2.70180","url":null,"abstract":"<p><p>Desiccation tolerance (DT), the ability to survive near-complete cellular dehydration, is widespread in diaspores but rare in the vegetative tissues of land plants. The patchy and punctuated phylogenetic distribution of vegetative desiccation tolerance (VDT) suggests that the trait is both ancient and recurrent, yet the evolutionary trajectories remain unresolved. Here, we synthesize evidence across land plants to propose a framework for the evolution of VDT in embryophytes. We build on the current understanding of VDT as an ancestral trait, present in the gametophyte of early land plants. The transition to sporophyte dominance and resulting homiohydry in vascular plants coincides with the widespread loss of VDT, likely driven by relaxed selection for VDT, coupled with new structural constraints and anatomical innovations that facilitated water acquisition, transport, and retention. The core molecular modules of DT were retained in the diaspores of most land plants, where they served as evolutionary refugia for the essential building blocks of the trait. Some species later reestablished VDT by co-opting deeply conserved diaspore modules and evolving key anatomical innovations to support them. We argue that such reestablishments of VDT are dependent on both anatomical predispositions as well as exposure to key selective pressures and ecological filters. We conclude that VDT is not a simple presence-absence trait, but rather a modular system, subject to anatomical constraints and contingent on the ecological context. Ultimately, we suggest that VDT serves as an elegant example of how complex traits emerge, persist, and shift across time.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70180"},"PeriodicalIF":2.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13103618/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147508855","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":"Strong differentiation between ancestral populations from low and high elevation: Implications for invasion biology.","authors":"Özkan Eren, José L Hierro","doi":"10.1002/ajb2.70184","DOIUrl":"10.1002/ajb2.70184","url":null,"abstract":"<p><strong>Premise: </strong>The differentiation of native populations at regional scales may limit evolutionary inferences derived from comparisons between native and non-native populations in common gardens, but little is known about how native populations of invasive species vary along environmental gradients at a regional scale.</p><p><strong>Methods: </strong>We used a common garden to explore differentiation in several traits between ancestral populations of Centaurea solstitialis growing at low and high elevation in southwestern Anatolia, a region considered to be one of the sources that contributed to the global expansion of this species.</p><p><strong>Results: </strong>Population differentiation was strong for all studied traits. Populations from low elevation produced smaller seeds, emerged and grew faster, flowered earlier, produced smaller and more numerous capitula per plant, and had larger individuals than those from high elevation. However, seed production per individual in low-elevation populations was similar to that in high-elevation populations because the capitula in high-elevation populations produced more seeds. Most notably, the seed type bearing a pappus was more abundant in higher-elevation populations than lower, but the abundance of non-pappus seeds exhibited no differences between those populations (capitulum level) or decreased with elevation (individual level).</p><p><strong>Conclusions: </strong>Our findings highlight the need to consider intraspecific variation at regional scales within native ranges, when attempting to infer evolutionary consequences based on comparisons between native and non-native populations of invasive species. Furthermore, a strong inference of evolutionary change in non-native populations may require knowledge of interpopulation variation even within regions identified as donors of those populations.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70184"},"PeriodicalIF":2.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147618266","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":"Ectomycorrhizal fungal composition shows structured spatial variation around Sarcodes sanguinea and Corallorhiza striata.","authors":"Christopher P Bivins, Alija B Mujic","doi":"10.1002/ajb2.70183","DOIUrl":"10.1002/ajb2.70183","url":null,"abstract":"<p><strong>Premise: </strong>Fully mycoheterotrophic plants obtain carbon from ectomycorrhizal (ECM) fungi, but whether these interactions are strictly parasitic or more context-dependent remains unresolved. Previous work on Sarcodes sanguinea suggested its fungal symbiont, Rhizopogon ellenae, achieves local dominance near the plant, raising the possibility of reciprocal benefit. Here, we asked whether two unrelated mycoheterotrophs exhibit similar patterns of localized fungal dominance and shifts in ECM community composition.</p><p><strong>Methods: </strong>We sampled soils and pooled ECM root tips from S. sanguinea and Corallorhiza striata rootballs and along transects up to 500 cm away in Sierra Nevada forests (California, USA). Fungal communities were characterized with ITS metabarcoding and analyzed for proximity-related changes in symbiont abundance, ECM richness, and community turnover.</p><p><strong>Results: </strong>S. sanguinea rootballs were highly enriched with Rhizopogon ellenae sequences, but the enrichment declined steeply with distance. More than half of ECM operational taxonomic units (OTUs) present outside rootballs were absent inside. For C. striata, Tomentella fuscocinerea showed a weaker distance-related gradient in soil samples but was most abundant on root tips inside rootballs, with relative abundance declining outward. Both species were associated with reduced ECM richness inside rootballs compared to surrounding soils.</p><p><strong>Conclusions: </strong>These results replicate earlier findings for S. sanguinea and extend them to an orchid lineage using DNA metabarcoding. The co-occurrence of focal symbiont enrichment and reduced ECM richness suggests that mycoheterotrophs are not simply parasites but contribute to localized community restructuring. This work underscores the need for experimental approaches to test whether these interactions yield reciprocal benefits for fungal partners.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70183"},"PeriodicalIF":2.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147589448","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":"Flower color variation in Digitalis purpurea: Pollination and soil influences across native and introduced populations.","authors":"Sissi Lozada-Gobilard, Pamela Espinoza Peñaloza, Giovanni Pascucci, Zainab Aliwi, Emilia Larsson, Mikkel Brydegaard, Øystein H Opedal","doi":"10.1002/ajb2.70186","DOIUrl":"10.1002/ajb2.70186","url":null,"abstract":"<p><strong>Premise: </strong>Flower color, a key trait influencing plant-pollinator interactions, may be influenced by abiotic factors such as soil. We investigated association between pollinators, soil characteristics, and flower color variations in Digitalis purpurea across native populations in Sweden and introduced populations in Bolivia.</p><p><strong>Methods: </strong>We measured floral traits, reflectance of petals and nectar-guide spots, plant size, pollinator visitation, fruit set, seed production, germination, and soil characteristics.</p><p><strong>Results: </strong>Individuals were categorized into violet, pink, and white morphs, which were confirmed by spectral measurements and bee vision modelling. Reflectance of inner nectar-guide spots overlapped across morphs, potentially limiting pollinator discrimination. Bumblebees were the main pollinators in all populations. Although visitation varied among morphs, pollinator visits to different color morphs were population specific. In Bolivia, violet flowers were predominant (70-87%), with pink (13-17%) and white (0-13%) at lower frequencies. In Sweden, morph frequencies were more even (violet 20-43%, pink 38-69%, white 11-30%). Morph frequency was not associated with soil composition, despite differences between regions. Reproductive fitness varied across populations but not consistently among morphs: The largest Swedish population had the highest fruit set but the lowest seed set, while germination was lower in Bolivia. Phosphorus was lower in soil beneath violet individuals; other soil variables, plant size, and floral traits did not differ among color morphs.</p><p><strong>Conclusions: </strong>Floral color variation in D. purpurea was not significantly related to pollinator visitation or soil conditions at the spatial scale examined, suggesting maintenance by local environmental conditions, neutrality, or historical and demographic processes rather than selection.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70186"},"PeriodicalIF":2.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13103626/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147607801","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":"What we learn from weed genetics.","authors":"Acer VanWallendael","doi":"10.1002/ajb2.70190","DOIUrl":"10.1002/ajb2.70190","url":null,"abstract":"","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70190"},"PeriodicalIF":2.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13103617/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147632367","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":"Fungal endophytes of an endangered tree vary with stress and microenvironment in an ex situ conservation nursery.","authors":"Brooke E Sykes, François Lutzoni, Annabel Renwick, Shuzo Oita, Shannon M Skarha, A Elizabeth Arnold","doi":"10.1002/ajb2.70181","DOIUrl":"10.1002/ajb2.70181","url":null,"abstract":"<p><strong>Premise: </strong>Plants in ex situ conservation nurseries acquire diverse fungal associates that may be moved among nurseries or into the wild during outplanting, including fungal endophytes that contribute to a broad range of functions and occur in leaves, sometimes alongside pathogens. To improve understanding of fungal symbionts in a plant of high conservation concern, we characterized foliar fungal endophytes of Torreya taxifolia, one of the world's most threatened conifers, in an ex situ conservation nursery.</p><p><strong>Methods: </strong>We used culture-based and culture-free approaches to characterize fungal endophytes in leaves of T. taxifolia over 2 years and evaluated how endophytes varied spatially and as a function of environmental, plant-specific, and edaphic factors. We also contrasted them with fungi in other plants (local species and species cultivated at a regional scale) and with soil fungi.</p><p><strong>Results: </strong>Culture-free methods revealed species-rich and phylogenetically diverse foliar fungal endophytes of T. taxifolia that vary spatially, reflecting symbiont acquisition from nearby plants, environmental factors, and plant stress. Endophyte community composition is subject to both stochasticity and temporal turnover and differs markedly from fungal communities in soils and other plants in the area.</p><p><strong>Conclusions: </strong>Our study provides novel insights into factors that can shape fungal endophyte communities for a critically endangered tree species. In addition to identifying local determinants of endophytic symbioses, our work illustrates that plants in conservation nurseries host rich foliar fungal communities of potential importance in plant germplasm protection.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70181"},"PeriodicalIF":2.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147525354","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":"Drivers of insect herbivory resistance and tolerance to plant damage in the Brachypodium distachyon species complex.","authors":"Antonio J Manzaneda, Luisa M Martínez, Ana Fernández-Ocaña, Teresa Salido, Pedro J Rey","doi":"10.1002/ajb2.70176","DOIUrl":"10.1002/ajb2.70176","url":null,"abstract":"<p><strong>Premise: </strong>Insect herbivory is a major biotic factor shaping plant populations and driving the evolution of defensive traits. Polyploidy (whole-genome duplication) often induces substantial phenotypic and genotypic changes that may affect species interactions, including herbivory. However, natural variation in herbivory responses and the drivers of resistance and tolerance across heteroploid lineages remain poorly understood.</p><p><strong>Methods: </strong>We conducted a bioassay to quantify variation in plant damage and tolerance to locust herbivory across multiple diploid and allotetraploid populations of the Brachypodium distachyon species complex, a model system comprising two diploid species (B. distachyon and B. stacei) and their allotetraploid derivative (B. hybridum). For each species, we also examined which plant functional traits were associated with resistance and tolerance to herbivory.</p><p><strong>Results: </strong>Herbivory reduced maternal fitness across the species complex, although its magnitude depended on species and the fitness component considered. Our results do not support enhanced herbivory resistance or tolerance in the allotetraploid lineage: Levels of plant damage in B. hybridum were comparable to those of one diploid parent (B. distachyon), and diploid B. distachyon had higher tolerance than B. hybridum for two of three fitness estimators. Variation in resistance was associated with differences in plant traits, particularly C:N ratio and silica content. In B. distachyon, tolerance was negatively associated with silica and water content, suggesting allocation trade-offs between resistance- and tolerance-related traits.</p><p><strong>Conclusions: </strong>Overall, our findings indicate that variation in herbivory responses across Brachypodium populations is more closely linked to population history and trait differentiation than to polyploid formation per se.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70176"},"PeriodicalIF":2.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13103616/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147466661","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":"Comparing six nonlinear equations describing the 2-D profiles of apical meristems.","authors":"Peijian Shi, Xiaonan Liu, Johan Gielis, Bert Beirinckx, Karl J Niklas","doi":"10.1002/ajb2.70177","DOIUrl":"10.1002/ajb2.70177","url":null,"abstract":"<p><strong>Premise: </strong>Shoot and root apical meristems (SAMs and RAMs, respectively) drive primary vascular plant growth, yet their 2-D profile geometries remain poorly quantified. Shoot and root apical meristems differ in evolutionary origin, cellular organization, and developmental context, prompting investigation into whether their shapes differ within and across angiosperms, gymnosperms, and representative seedless vascular plants.</p><p><strong>Methods: </strong>SAM and RAM profiles from 11 representative taxa were extracted from histological images. Six nonlinear equations (the catenary, parabolic, hybrid catenary-parabolic, performance, superparabolic, and superellipse equations) were fitted to normalized profile coordinates. Model performance was evaluated using the Akaike information criterion (AIC).</p><p><strong>Results: </strong>The superparabolic equation provided the best fit for eight of 16 of the SAM and RAM profiles, as evidenced by the lowest AIC values, whereas the hybrid catenary-parabolic equation performed best for five profiles. These two equations outperformed the other four, though no single model was universally superior across all profiles. Although meristem shapes differed, SAM and RAM geometries showed no consistent differences across the three plant groupings.</p><p><strong>Conclusions: </strong>Both the superparabolic and hybrid catenary-parabolic equations provide robust descriptions of SAM and RAM profiles, perhaps reflecting a convergence in apical meristem geometry across otherwise divergent vascular plant lineages. This quantitative approach offers a potential tool for comparing meristem geometry and shape that can be extended to the study of nonvascular plants to increase our understanding of plant form, evolution, and meristem functionality.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70177"},"PeriodicalIF":2.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147479501","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":"Population genetics and phylogenomic insights into the origin of economically important black pepper (Piper nigrum).","authors":"Dominik Metschina, Luiz A Cauz-Santos, Maarten J M Christenhusz, Nilni A Wimalarathna, Tara D Silva, Andreas Berger, James W Byng, Harsha Dissanayake, Deepthi Yakandawala, Anushka M Wickramasuriya, Barbara Turner, Mark W Chase, Rosabelle Samuel","doi":"10.1002/ajb2.70187","DOIUrl":"10.1002/ajb2.70187","url":null,"abstract":"<p><strong>Premise: </strong>We conducted population genetic and phylogenomic analyses of several cultivated Piper nigrum varieties and closely related species. We sought to establish (1) the genetic constitution of P. nigrum and its putative status as an allotetraploid hybrid of Indian origin, and (2) its relationships to other species of Piper in South and Southeast Asia.</p><p><strong>Methods: </strong>We analyzed high-quality data comprising single nucleotide polymorphisms (SNPs) using RAxML, a phylogenetic network approach, and coancestry analyses to examine phylogenetic relationships. We included two putative parental species of the hypothesized allotetraploid P. nigrum (P. galeatum and P. trichyostachyon) and a set of Sri Lankan endemic species. We also determined genome sizes of several species.</p><p><strong>Results: </strong>A clade comprising Sri Lankan endemics is more closely related to cultivated P. nigrum than the two Indian species. Most cultivated varieties of P. nigrum are autotetraploids that can be distinguished genetically, but among them are some diploid accessions.</p><p><strong>Conclusions: </strong>Piper nigrum is a member of a clade of Sri Lankan endemics and did not originate via hybridization between the previously suggested parental species, P. galeatum and P. trichostachyon. Autotetraploid varieties of Piper nigrum are predominant in cultivation, probably due to their increased vigor and higher yields, although diploid varieties are also present, demonstrating that genome duplication probably occurred recently in cultivation.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70187"},"PeriodicalIF":2.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13103621/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147643678","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":"Phylotranscriptomics and genome size evolution in Leucaena (Fabaceae): Paleotetraploid genomic stability overshadows diploidization and environmental effects.","authors":"Alex Abair, Ashley N Egan, Brittany Bugg, Madhugiri Nageswara-Rao, Colin E Hughes, Kitti Denson, Mike Lopez, Hailey Sermersheim, Joshua T Trujillo, Shannon C K Straub, Jessica P Houston, Ya Yang, Susan R Strickler, Richard C Cronn, Aaron Liston, Carl E Hjelmen, C Donovan Bailey","doi":"10.1002/ajb2.70178","DOIUrl":"10.1002/ajb2.70178","url":null,"abstract":"<p><strong>Premise: </strong>Advances in transcriptomic and reduced representation genomic sequencing are deepening our understanding of how hybridization, reticulation, and environmental variation impact species diversification and genome size. Leucaena is a useful system for exploring the genomic basis of allopatric and allopolyploid speciation events and the effect of environmental pressures on genome size across 30° of latitude. We investigate phylogenetic relationships, the roles of polyploidy and hybridization in speciation, and genome size evolution in the genus.</p><p><strong>Methods: </strong>Using newly generated RNA-sequencing data for Leucaena, we applied reference-guided and de novo phylotranscriptomics to reconstruct nuclear and organellar phylogenies. We then used comparative genome sizes from 252 samples and phylogenetic methods to investigate genome size evolution broadly and the impacts of environmental variables specifically.</p><p><strong>Results: </strong>The phylogenetic results supported cladogenetic, rather than reticulate/hybrid, origins for most of the 19 paleotetraploid species. By contrast, gene tree data supported hybrid origins for octoploid Leucaena. The ancestral paleotetraploid genome size (1.52 pg/2 C) is relatively conserved among the paleotetraploids, rejecting our hypothesis associated with environmental variables significantly impacting genome sizes.</p><p><strong>Conclusions: </strong>The phylogenetic results illustrate the complex interplay of intrinsic and external factors that impact speciation, including ancient whole-genome duplication (WGD), cladogenesis, secondary contact, and allopolyploidy. A weak relationship between genome size and environmental variables suggests that other factors, including paleotetraploid genomic stability, have constrained genome size variation following a WGD 16+ million years ago. The findings are consistent with a small but growing number of studies identifying groups with ancient WGDs that resist diploidization associated with gene and DNA loss.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70178"},"PeriodicalIF":2.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147508826","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}