Plant Clades Research Articles

Convergent evidence for the temperature-dependent emergence of silicification in terrestrial plants

Research on silicon (Si) biogeochemistry and its beneficial effects for plants has received significant attention over several decades, but the reasons for the emergence of high-Si plants remain unclear. Here, we combine experimentation, field studies and analysis of existing databases to test the role of temperature on the expression and emergence of silicification in terrestrial plants. We first show that Si is beneficial for rice under high temperature (40 °C), but harmful under low temperature (0 °C), whilst a 2 °C increase results in a 37% increase in leaf Si concentrations. We then find that, globally, the average distribution temperature of high-Si plant clades is 1.2 °C higher than that of low-Si clades. Across China, leaf Si concentrations increase with temperature in high-Si plants (wheat and rice), but not in low-Si plants (weeping willow and winter jasmine). From an evolutionary perspective, 77% of high-Si families (>10 mg Si g−1 DW) originate during warming episodes, while 86% of low-Si families (<1 mg Si g−1 DW) originate during cooling episodes. On average, Earth’s temperature during the emergence of high-Si families is 3 °C higher than that of low-Si families. Taken together, our evidence suggests that plant Si variation is closely related to global and long-term climate change.

Rocksitter Flies (Lauxaniidae: Cestrotus) are Key‐Pollinators of Ceropegia pulchellior—A Threatened and Localised South African Endemic With Foetid‐Scented Flowers

ABSTRACTShort‐tongued saprophilous flies are a diverse but under‐appreciated group of pollinators, which are particularly important for flowers in the subtribe Stapeliinae (Apocynaceae‐Asclepiadoideae‐Ceropegieae). This clade of plants is characterised by repeated shifts between tubular kettle‐trap and open non‐trap flowers and chemical mimicry (of decomposing substrates or dying insects) to attract specific fly pollinators. The biology of most Stapeliinae, particularly those with non‐trap flowers, remains poorly studied, hampering our understanding of the mechanisms driving diversification in this plant group. We examined the pollination biology and floral traits of Ceropegia pulchellior, a South African endemic with non‐trap flowers confined to Natal Group Sandstone on the Durban escarpment. Observations showed that flowers are visited exclusively by flies which forage on small amounts of nectar in the corona cavities. Flowers were pollinated primarily by lauxaniid flies in the genus Cestrotus, although several muscid fly species also contribute. Pollinator exclusion experiments confirmed that the plants depend on these flies for reproduction. Reproductive success was low (fruit set never exceeding 8% of flowers). Pollen transfer efficiency was relatively high but variable across the flowering period. GC–MS analysis of floral scent revealed that the foetid odour is dominated by aliphatic acids and p‐cresol with small amounts of indole, supporting the assumption that C. pulchellior mimics decaying substrates to selectively attract detritus‐feeding (saprophagous) flies as pollinators. Analysis of spectral reflectance of flowers indicates that flower colours, when viewed by the fly pollinators, are not chromatically distinct from the habitat background, suggesting that flowers rely on olfactory rather than visual signals to attract pollinators. This study contributes to the growing awareness of the complexity of pollination systems in the Stapeliinae, in terms of the wide diversity of fly taxa involved, the intricate pollen transfer mechanisms, and the unusual floral scent chemistry associated with mimicry of oviposition substrates and food sources.

Macroevolutionary inference of complex modes of chromosomal speciation in a cosmopolitan plant lineage.

The effects of single chromosome number change-dysploidy - mediating diversification remain poorly understood. Dysploidy modifies recombination rates, linkage, or reproductive isolation, especially for one-fifth of all eukaryote lineages with holocentric chromosomes. Dysploidy effects on diversification have not been estimated because modeling chromosome numbers linked to diversification with heterogeneity along phylogenies is quantitatively challenging. We propose a new state-dependent diversification model of chromosome evolution that links diversification rates to dysploidy rates considering heterogeneity and differentiates between anagenetic and cladogenetic changes. We apply this model to Carex (Cyperaceae), a cosmopolitan flowering plant clade with holocentric chromosomes. We recover two distinct modes of chromosomal evolution and speciation in Carex. In one diversification mode, dysploidy occurs frequently and drives faster diversification rates. In the other mode, dysploidy is rare, and diversification is driven by hidden, unmeasured factors. When we use a model that excludes hidden states, we mistakenly infer a strong, uniformly positive effect of dysploidy on diversification, showing that standard models may lead to confident but incorrect conclusions about diversification. This study demonstrates that dysploidy can have a significant role in speciation in a large plant clade despite the presence of other unmeasured factors that simultaneously affect diversification.

Nutrient availability explains distinct soil fungal colonization of angiosperm versus gymnosperm wood

Abstract Soil fungi play an essential role in the fungal colonization of deadwood, with consequences for multiple ecosystem functions such as wood decomposition. Nutrient deposition can substantially affect fungal activity, but it is unclear how external nutrient inputs and host plant nutrient content interact to influence soil fungal colonization of deadwood. To advance understanding of fungal dynamics during deadwood decomposition, we conducted a field experiment with eight tree species (four angiosperms and four gymnosperms) under four nutrient additions (no nutrient addition, nitrogen (N)‐addition, phosphorus (P)‐addition and combined N‐ and P‐addition), to investigate fungal colonization and communities in different host plant clades (angiosperms and gymnosperms) over 3 years. The study revealed that host plant clade and nutrient availability interact significantly, which strongly influenced soil fungal colonization of deadwood. The percentage of shared fungi (present in both soil and deadwood) was higher in angiosperms (38.1%–47.3%) than in gymnosperms (26.5%–36.5%). Saprotrophs were the dominant functional group in the shared fungal community, with symbiotrophs as the next most abundant group, and the dominant fungal taxa were mainly K‐strategists, which were more abundant in gymnosperms than in angiosperms. Notably, there was a stronger connection between soil fungi and deadwood fungi in gymnosperms compared to angiosperms, which was likely related to the importance of K‐strategist fungi for decomposing wood with low nutrient content. Overall, the shared fungal community in angiosperms was more sensitive to nutrient addition than in gymnosperms, resulting in greater changes to fungal taxa and functional groups. In angiosperm wood, N‐addition significantly increased α‐diversity but decreased β‐diversity of the shared fungal community, indicating N‐limitation. In gymnosperm wood, P‐addition significantly reduced both α‐diversity and β‐diversity of the shared fungal community, indicating P‐limitation. Synthesis. Our study demonstrates the divergent effect of nutrient addition on fungal colonization in angiosperms versus gymnosperms. Considering interactions between inherent plant traits and exogenous nutrient availabilities thus provides a more comprehensive understanding of the association between soil fungi and deadwood fungi during wood decomposition.

Plastid Phylogenomic Analysis of Podostemaceae with an Emphasis on Neotropical Podostemoideae

Abstract— Podostemaceae are a clade of aquatic flowering plants that form important components of tropical river ecosystems. Species in the family exhibit highly derived growth forms and high vegetative phenotypic plasticity, both of which contribute to taxonomic confusion. The backbone phylogeny of the family remains poorly resolved, many species remain to be included in a molecular phylogenetic analysis, and the monophyly of many taxa remains to be tested. To address these issues, we assembled sequence data for 73 protein-coding plastid genes from 132 samples representing 68 species (∼23% of described species) that span the breadth of most major taxonomic, morphological, and biogeographic groups of Podostemaceae. With these data, we conducted the first plastid phylogenomic analysis of the family with broad taxon sampling. These analyses resolved most nodes with high support, including relationships not recovered in previous analyses. No evidence of widespread, well-supported conflict among individual plastid genes and the concatenated phylogeny was observed. We present new evidence that four genera (Apinagia, Marathrum, Oserya, and Podostemum), as well as four species, are not monophyletic. In particular, we show that Podostemum flagelliforme should not be included in Podostemum and is better recognized as Devillea flagelliformis, and that Marathrum capillaceum is embedded within Lophogyne s.l. and should be recognized as Lophogyne capillacea. We also place a previously unsampled and undescribed species that likely represents a new genus. In contrast to previous studies, the neotropical genera Diamantina, Ceratolacis, Cipoia, and Podostemum are resolved as successive sister groups to a clade of all paleotropical Podostemoideae taxa sampled, suggesting a single dispersal event from the neotropics to the paleotropics in the history of the subfamily. These results provide a strong basis for improving the classification of Podostemaceae and a framework for future phylogenomic studies of the clade employing data from the nuclear genome.

Genetic architecture underlying the parallel evolution of leaf ecomorphs in Viburnum

Abstract In a neotropical lineage of the plant clade Viburnum (Adoxaceae) several leaf ecomorphs evolved independently and repeatedly as the group radiated through cloud forests of North and South America. Here, we focus on one pair of co-occurring sister species within this radiation with strongly contrasting leaf morphotypes and document the presence of phenotypically diverse and genetically admixed hybrid individuals in multiple hybrid swarms. Hybrid phenotypes are generally intermediate in form, but sometimes show parental or entirely novel and transgressive combinations of leaf traits, suggesting that parental leaf ecomorphs can be functionally and genetically dissociated. We used admixture mapping within hybrid swarms to investigate the genetic architecture of key traits comprising these leaf ecomorphs and uncovered loci proximal to known genes implicated in leaf development, including some that may alter multiple leaf traits simultaneously, potentially facilitating the emergence of leaf syndromes. We conclude that the shared genetic architecture underlying some traits, such as leaf size and marginal teeth, could promote the repeated evolution of these traits in concert, while low levels of genetic linkage between other leaf traits supports the hypothesis that selection promoted the repeated assembly of particular combinations of leaf traits as Viburnum radiated throughout the neotropics.

Evolution and development of complex floral displays.

Flowering plants - angiosperms - display an astounding diversity of floral features, which have evolved in response to animal pollination and have resulted in the most species-rich plant clade. Combinations of macroscale (e.g. colour, symmetry, organ number) and microscale (e.g. cell type, tissue patterning) features often lead to highly elaborate floral displays. Most studies have focused on model species with simple floral displays to uncover the genetic and evolutionary mechanisms involved in flower evolution, yet few studies have focused on complex floral displays. Here, we review current knowledge on the development and evolution of complex floral displays. We review gene regulatory networks involved in four developmental pathways contributing to overall floral display (inflorescence architecture, organ identity, flower symmetry and flower colour) in classical plant models. We then discuss how evolutionary modification of one or more of these pathways has resulted in the production of a range of complex floral displays. Finally, we explore modular systems in which multiple pathways have been modified simultaneously, generating the most elaborate floral displays.

A Molecular Temporal Evolutionary Framework of Land Plants and the Age of Angiosperms

A series of Bayesian molecular clock analyses with varying model combinations, parameters, and tree topologies were conducted to establish a temporal evolutionary framework of land plants and to estimate the age of angiosperms. The data consisted of five organellar and nuclear genes, 633 taxa, and 23 fossil calibration points (FCPs). The analyses were evaluated using an internal search thoroughness measure, effective sample sizes, and two external criteria: the consensus land plant phylogeny and a newly developed method that used the Hennigian reciprocal illumination principle to compare molecular age estimates of 21 nodes representing major land plant clades and the root split in green plants with those of their fossils in an a posteriori fashion. The results show that an analysis using a general time reversible (GTR) DNA substitution model, log normal branch-rate distribution, and Yule tree prior represented the best model combination, with the Birth-Death tree prior being equally optimal. This analysis estimated the age of the land plant crown group as 496.95 million years (MY), with a 95% highest posterior density (HPD) of 465.66–531.43 MY, and the age of the angiosperm crown group as 219.93 MY, with a 95% HPD of 184.09–256.82 MY. The former agrees with the fossil evidence, but the latter is significantly older than the fossil ages. A thorough examination of fossil evidence of angiosperms, as well as their evolutionary history in light of recent knowledge of morphology, physiology, and atmospheric CO2 concentration in the Mesozoic era, suggests that angiosperm radiation might have been delayed after their origin and that the current fossil record probably reflects only the products of that radiation, not the origin of angiosperms. Overall, the study shows that both molecular clock analyses and fossil studies, while agreeing on some aspects but disagreeing on others, can help develop a complete understanding of the temporal evolutionary history of land plants.

Evolution of Thylakoid Structural Diversity.

Oxygenic photosynthesis evolved billions of years ago, becoming Earth's main source of biologically available carbon and atmospheric oxygen. Since then, phototrophic organisms have diversified from prokaryotic cyanobacteria into several distinct clades of eukaryotic algae and plants through endosymbiosis events. This diversity can be seen in the thylakoid membranes, complex networks of lipids, proteins, and pigments that perform the light-dependent reactions of photosynthesis. In this review, we highlight the structural diversity of thylakoids, following the evolutionary history of phototrophic species. We begin with a molecular inventory of different thylakoid components and then illustrate how these building blocks are integrated to form membrane networks with diverse architectures. We conclude with an outlook on understanding how thylakoids remodel their architecture and molecular organization during dynamic processes such as biogenesis, repair, and environmental adaptation.

Evolution of small molecule-mediated regulation of arbuscular mycorrhiza symbiosis.

The arbuscular mycorrhizal (AM) symbiosis formed by most extant land plants with symbiotic fungi evolved 450 Ma. AM promotes plant growth by improving mineral nutrient and water uptake, while the symbiotic fungi obtain carbon in return. A number of plant genes regulating the steps leading to an efficient symbiosis have been identified; however, our understanding of the metabolic processes involved in the symbiosis and how they were wired to symbiosis regulation during plant evolution remains limited. Among them, the exchange of chemical signals, the activation of dedicated biosynthesis pathways and the production of secondary metabolites regulating late stages of the AM symbiosis begin to be well described across several land plant clades. Here, we review our current understanding of these processes and propose future directions to fully grasp the phylogenetic distribution and role played by small molecules during this ancient plant symbiosis. This article is part of the theme issue 'The evolution of plant metabolism'.

An efficient and effective RNA extraction protocol for ferns.

The extraction of high-quality RNA is the critical first step for the analysis of gene expression and gene space. This remains particularly challenging in plants, and especially in ferns, where the disruption of the cell wall and separation of organic compounds from nucleic acids is not trivial. We developed a cetyltrimethylammonium bromide (CTAB)-based RNA extraction protocol that consistently performs well across a large phylogenetic breadth of ferns-a lineage of plants high in secondary compounds-and in an array of tissue types. Two alternative options (precipitation vs. clean-up without intermediate precipitation) are presented, both of which yield high-quality RNA extracts with optical density (OD) ratios of OD 260/280 = 1.9-2.1 and OD 260/230 > 1.6, and RNA integrity numbers >7. This study presents an efficient protocol for the extraction of high-quality RNA from multiple tissues and across the fern phylogeny, a clade of plants that still lags behind other major lineages in the development of genomic resources. We hope that this method can be used to help facilitate the closing of this gap.

A Phylogenetic Model of Established and Enabled Biome Shifts.

Where each species actually lives is distinct from where it could potentially survive and persist. This suggests that it may be important to distinguish established from enabled biome affinities when considering how ancestral species moved and evolved among major habitat types. We introduce a new phylogenetic method, called RFBS, to model how anagenetic and cladogenetic events cause established and enabled biome affinities (or, more generally, other discrete realized versus fundamental niche states) to shift over evolutionary timescale. We provide practical guidelines for how to assign established and enabled biome affinity states to extant taxa, using the flowering plant clade Viburnum as a case study. Through a battery of simulation experiments, we show that RFBS performs well, even when we have realistically imperfect knowledge of enabled biome affinities for most analyzed species. We also show that RFBS reliably discerns established from enabled affinities, with similar accuracy to standard competing models that ignore the existence of enabled biome affinities. Lastly, we apply RFBS to Viburnum to infer ancestral biomes throughout the tree and to highlight instances where repeated shifts between established affinities for warm and cold temperate forest biomes were enabled by a stable and slowly-evolving enabled affinity for both temperate biomes.

Geographic patterns and climatic drivers of phylogenetic structure of liverworts along a long elevational gradient in the central Himalaya

AbstractFor clades originating in warm climates, the tropical niche conservatism hypothesis predicts that current biological assemblages in colder or drier climates are expected to have lower phylogenetic diversity, and species in colder or drier climates are expected to be more closely related to each other (i.e., higher phylogenetic clustering). Liverworts are one of the oldest clades of extant land plants. They originated about 500 Ma during a warm (“greenhouse”) period and experienced multiple major cycles of warm and cold periods. Here, I test the tropical niche conservatism hypothesis using liverwort assemblages distributed along an elevational gradient crossing about 5000 m of elevation in the central Himalaya. I found that, in general, phylogenetic diversity and dispersion decrease with increasing elevation and thus with decreasing temperature, which is consistent with the tropical niche conservatism hypothesis. Phylogenetic diversity decreases with elevation monotonically, but phylogenetic dispersion decreases with elevation in a triphasic (zig‐zag) pattern, which is generally consistent with the triphasic pattern found in angiosperms and polypod ferns along the same elevational gradient. Temperature‐related variables explained approximately the same amount of the variation in phylogenetic diversity and dispersion as did precipitation‐related variables, although mean annual temperature explained 9%−15% more variation than did annual precipitation. Climate extreme variables explained approximately the same amount of variation in phylogenetic diversity and dispersion as did climate seasonality variables.

Phylogenetic evidence clarifies the history of the extrusion of Indochina

The southeastward extrusion of Indochina along the Ailao Shan-Red River shear zone (ARSZ) is one of two of the most prominent consequences of the India-Asia collision. This plate-scale extrusion has greatly changed Southeast Asian topography and drainage patterns and effected regional climate and biotic evolution. However, little is known about how Indochina was extruded toward the southeast over time. Here, we sampled 42 plant and animal clades (together encompassing 1,721 species) that are distributed across the ARSZ and are not expected to disperse across long distances. We first assess the possible role of climate on driving the phylogenetic separations observed across the ARSZ. We then investigate the temporal dynamics of the extrusion of Indochina through a multitaxon analysis. We show that the lineage divergences across the ARSZ were most likely associated with the Indochinese extrusion rather than climatic events. The lineage divergences began at ~53 Ma and increased sharply ~35 Ma, with two peaks at ~19 Ma and ~7 Ma, and one valley at ~13 Ma. Our results suggest a two-phase model for the extrusion of Indochina, and in each phase, the extrusion was subject to periods of acceleration and decrease, in agreement with the changes of the India-Asia convergence rate and angle from the early Eocene to the late Miocene. This study highlights that a multitaxon analysis can illuminate the timing of subtle historical events that may be difficult for geological data to pinpoint and can be used to explore other tectonic events.

Hyperaccumulation of nickel but not selenium drives floral microbiome differentiation: A study with six species of Brassicaceae.

Intraspecific variation in flower microbiome composition can mediate pollination and reproduction, and so understanding the community assembly processes driving this variation is critical. Yet the relative importance of trait-based host filtering and dispersal in shaping among-species variation in floral microbiomes remains unknown. Within two clades of Brassicaceae, we compared diversity and composition of floral microbiomes in natural populations of focal nickel and selenium hyperaccumulator species and two of their non-accumulating relatives. We assessed the relative strengths of floral elemental composition, plant phylogenetic distance (host filtering), and geography (dispersal) in driving floral microbiome composition. Species in the nickel hyperaccumulator clade had strongly divergent floral microbiomes, the most of that variation driven by floral elemental composition, followed by geographic distance between plant populations and, lastly, phylogenetic distance. Conversely, within the selenium hyperaccumulator clade, floral microbiome divergence was much lower among the species and elemental composition, geography, and plant phylogeny were far weaker determinants of microbiome variation. Our results show that the strength of elemental hyperaccumulation's effect on floral microbiomes differs substantially among plant clades, possibly due to variation in elements as selective filters or in long-distance dispersal probability in different habitats.

Limited effects of xylem anatomy on embolism resistance in cycad leaves.

Drought-induced xylem embolism is a primary cause of plant mortality. Although c. 70% of cycads are threatened by extinction and extant cycads diversified during a period of increasing aridification, the vulnerability of cycads to embolism spread has been overlooked. We quantified the vulnerability to drought-induced embolism, pressure-volume curves, in situ water potentials, and a suite of xylem anatomical traits of leaf pinnae and rachises for 20 cycad species. We tested whether anatomical traits were linked to hydraulic safety in cycads. Compared with other major vascular plant clades, cycads exhibited similar embolism resistance to angiosperms and pteridophytes but were more vulnerable to embolism than noncycad gymnosperms. All 20 cycads had both tracheids and vessels, the proportions of which were unrelated to embolism resistance. Only vessel pit membrane fraction was positively correlated to embolism resistance, contrary to angiosperms. Water potential at turgor loss was significantly correlated to embolism resistance among cycads. Our results show that cycads exhibit low resistance to xylem embolism and that xylem anatomical traits - particularly vessels - may influence embolism resistance together with tracheids. This study highlights the importance of understanding the mechanisms of drought resistance in evolutionarily unique and threatened lineages like the cycads.

Shifts in evolutionary lability underlie independent gains and losses of root-nodule symbiosis in a single clade of plants

Root nodule symbiosis (RNS) is a complex trait that enables plants to access atmospheric nitrogen converted into usable forms through a mutualistic relationship with soil bacteria. Pinpointing the evolutionary origins of RNS is critical for understanding its genetic basis, but building this evolutionary context is complicated by data limitations and the intermittent presence of RNS in a single clade of ca. 30,000 species of flowering plants, i.e., the nitrogen-fixing clade (NFC). We developed the most extensive de novo phylogeny for the NFC and an RNS trait database to reconstruct the evolution of RNS. Our analysis identifies evolutionary rate heterogeneity associated with a two-step process: An ancestral precursor state transitioned to a more labile state from which RNS was rapidly gained at multiple points in the NFC. We illustrate how a two-step process could explain multiple independent gains and losses of RNS, contrary to recent hypotheses suggesting one gain and numerous losses, and suggest a broader phylogenetic and genetic scope may be required for genome-phenome mapping.

Intra- and interspecific diversity in a tropical plant clade alter herbivory and ecosystem resilience

Declines in biodiversity generated by anthropogenic stressors at both species and population levels can alter emergent processes instrumental to ecosystem function and resilience. As such, understanding the role of biodiversity in ecosystem function and its response to climate perturbation is increasingly important, especially in tropical systems where responses to changes in biodiversity are less predictable and more challenging to assess experimentally. Using large-scale transplant experiments conducted at five neotropical sites, we documented the impacts of changes in intraspecific and interspecific plant richness in the genus Piper on insect herbivory, insect richness, and ecosystem resilience to perturbations in water availability. We found that reductions of both intraspecific and interspecific Piper diversity had measurable and site-specific effects on herbivory, herbivorous insect richness, and plant mortality. The responses of these ecosystem-relevant processes to reduced intraspecific Piper richness were often similar in magnitude to the effects of reduced interspecific richness. Increased water availability reduced herbivory by 4.2% overall, and the response of herbivorous insect richness and herbivory to water availability were altered by both intra- and interspecific richness in a site-dependent manner. Our results underscore the role of intraspecific and interspecific richness as foundations of ecosystem function and the importance of community and location-specific contingencies in controlling function in complex tropical systems.

Intra- and interspecific diversity in a tropical plant clade alter herbivory and ecosystem resilience.

Declines in biodiversity generated by anthropogenic stressors at both species and population levels can alter emergent processes instrumental to ecosystem function and resilience. As such, understanding the role of biodiversity in ecosystem function and its response to climate perturbation is increasingly important, especially in tropical systems where responses to changes in biodiversity are less predictable and more challenging to assess experimentally. Using large-scale transplant experiments conducted at five neotropical sites, we documented the impacts of changes in intraspecific and interspecific plant richness in the genus Piper on insect herbivory, insect richness, and ecosystem resilience to perturbations in water availability. We found that reductions of both intraspecific and interspecific Piper diversity had measurable and site-specific effects on herbivory, herbivorous insect richness, and plant mortality. The responses of these ecosystem-relevant processes to reduced intraspecific Piper richness were often similar in magnitude to the effects of reduced interspecific richness. Increased water availability reduced herbivory by 4.2% overall, and the response of herbivorous insect richness and herbivory to water availability were altered by both intra- and interspecific richness in a site-dependent manner. Our results underscore the role of intraspecific and interspecific richness as foundations of ecosystem function and the importance of community and location-specific contingencies in controlling function in complex tropical systems.

The N-terminal domains of NLR immune receptors exhibit structural and functional similarities across divergent plant lineages.

Nucleotide-binding domain and leucine-rich repeat (NLR) proteins are a prominent class of intracellular immune receptors in plants. However, our understanding of plant NLR structure and function is limited to the evolutionarily young flowering plant clade. Here, we describe an extended spectrum of NLR diversity across divergent plant lineages and demonstrate the structural and functional similarities of N-terminal domains that trigger immune responses. We show that the broadly distributed coiled-coil (CC) and toll/interleukin-1 receptor (TIR) domain families of nonflowering plants retain immune-related functions through translineage activation of cell death in the angiosperm Nicotiana benthamiana. We further examined a CC subfamily specific to nonflowering lineages and uncovered an essential N-terminal MAEPL motif that is functionally comparable with motifs in resistosome-forming CC-NLRs. Consistent with a conserved role in immunity, the ectopic activation of CCMAEPL in the nonflowering liverwort Marchantia polymorpha led to profound growth inhibition, defense gene activation, and signatures of cell death. Moreover, comparative transcriptomic analyses of CCMAEPL activity delineated a common CC-mediated immune program shared across evolutionarily divergent nonflowering and flowering plants. Collectively, our findings highlight the ancestral nature of NLR-mediated immunity during plant evolution that dates its origin to at least ∼500 million years ago.