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Background: Mitogenome sizes of seed plants vary substantially even among closely related species, which are often related to horizontal or intracellular DNA transfer (HDT or IDT) events. However, the mechanisms of this size variation have not been well characterized. Results: Here we assembled and characterized the mitogenomes of three species of Melastoma, a tropical shrub genus experiencing rapid speciation. The mitogenomes of M. candidum (Mc), M. sanguineum (Ms) and M. dodecandrum (Md) were assembled to a circular mapping chromosome of 391,595 bp, 395,542 bp and 412,026 bp, respectively. While the mitogenomes of Mc and Ms showed good collinearity except for a large inversion of ~ 150 kb, there were many rearrangements in the mitogenomes between Md and either Mc or Ms. Most non-alignable sequences (> 80%) between Mc and Ms are from gain or loss of mitochondrial sequences. Whereas, between Md and either Mc or Ms, non-alignable sequences in Md are mainly chloroplast derived sequences (> 30%) and from putative horizontal DNA transfers (> 30%), and those in both Mc and Ms are from gain or loss of mitochondrial sequences (> 80%). We also identified a recurrent IDT event in another congeneric species, M. penicillatum, which has not been fixed as it is only found in one of the three examined populations. Conclusions: By characterizing mitochondrial genome sequences of Melastoma, our study not only helps understand mitogenome size evolution in closely related species, but also cautions different evolutionary histories of mitochondrial regions due to potential recurrent IDT events in some populations or species. [ABSTRACT FROM AUTHOR]

Aim: Significant changes in species elevational ranges in mountains have been repeatedly documented, yet the direction, magnitude and drivers of these shifts remain controversial. Presently, there is still lacking evidence about the general nature of species elevational range shifts in eastern Eurasia in response to anthropogenic climate change. By using historical specimen records and recent field observations for 735 seed plant species across 29 China's mountains, we assessed changes in species' elevational centroids and their drivers. Location: China. Time Period: 1950–2018. Major Taxa Studied: Seed plant species. Methods: The elevation records of all sampled occurrences in each mountain during the two time periods were estimated, and the null models were developed to test the sampling bias. Ecological niche models (ENMs) were used to evaluate the relative importance of climate factors in constraining each species distribution. Generalized linear models (GLMs) to test the relationships between the centroid elevational range shifts of species and different divers. Results: We found that 54% of the species shifting upward and 46% downhill. However, species' elevational shifts significantly differed among species and mountains. Herbaceous and lowland species moved upward faster than woody and high‐elevation species. Species in temperate mountains and in mountains with taller elevational gradients moved upward, while species in subtropical mountains and in mountains with shorter elevational gradients moved downward. Precipitation changes experienced by species, species' climatic adaptations, several species' functional traits and mountain size all contributed to explain the magnitude of species' centroid elevational range shifts. Main Conclusions: Our results highlight complex biodiversity redistribution of seed plants across Chinese mountains, not necessarily conforming to the trend of species upward shifts in elevation. Changes in precipitation regimes may blur the simplistic assumption of isotherm tracking. This study fills an important geographic shortfall for our understanding of biodiversity redistribution under anthropogenic climate change. [ABSTRACT FROM AUTHOR]

The purpose of the study was to obtain new breeding genotypes containing a nuclear genome of a sugar beet sterility maintainer and sterile cytoplasm of wild beet (Beta patula L.). The donors of a new sterile cytoplasm of B. patula plants were selected by the indirect cytological traits of cytoplasmic male sterility (CMS), especially pollen sterility, abnormal development of the anthers, mosaic patterns of anthers and flowers. The anthers were examined for morphological traits of pollen and microspore degeneration in CMS. During reciprocal crosses, (i) the expression of recessive alleles of the nuclear genes of the CMS sterility maintainers was analysed, (ii) the peculiarities of hybridisation of the experimental genotypes with sterile B. patula cytoplasm were studied, and (iii) the selection of linked genes for hypocotyl colour Rr and one- or two-year growth cycle Bb was carried out. The obtained backcross offspring of BC3S B. patula had 95% fertility, 100% CMS-0 type sterility, and sugar content between 19.5% and 21.5%. Recombination in the locus of linked genes of the one- and two-year growth cycles and hypocotyl colour RB rb in hybrids F1, B. patula and backcross offspring was detected. At the same time, the oneand two-year growth cycle in seed plants was restored only in the 4th cycle of backcross. Recombinant genotypes with a red hypocotyl and two-year growth cycle BC3S B. patula had multi-seed fruits, single or branched stems of seed plants and were chimerical by sterility (CMS-1 and CMS-0 types). The obtained alloplasmic introduced lines containing the cytoplasm of B. patula have economically valuable properties as parent components for the development of new triploid hybrids. The experimental triploid hybrids had root sugar content from 19.5% to 20.5% and dry matter content from 25% to 29%. Alloplasmic lines with the new CMS of B. patula are recommended for sugar beet breeding. [ABSTRACT FROM AUTHOR]

Premise: In recent years, Doyleales have played an important role in the discussion and exploration of seed plant relationships and the origin of angiosperms. This order comprises a diversity of recently described genera with cupule‐bearing compound ovulate cones recovered from Early Cretaceous deposits in North America and Asia. Their relatively late appearance in the fossil record, stratigraphically near the appearance of angiosperms in the Early Cretaceous, has been noteworthy. Here, we report a new genus of Doyleales, Zirabia gen. nov. from the Early Jurassic of Iran, that was originally described as the ginkgophyte Karkenia. Methods: We reinvestigated material previously assigned to Karkenia cylindrica from the Lower Jurassic of the Zirab locality, Alborz Mountains, northern Iran. Results: The studied specimen features a main axis bearing helically to irregularly arranged bract‐cupule complexes, each composed by a long laminar bract subtending and sheathing a cupule stalk that bears a single‐seeded cupule with a dorsal protrusion. The morphological features of this taxon do not conform with those of Karkenia, and suggest affinities with Doyleales rather than Ginkgoales. Within Doyleales, this fossil has a unique combination of characters indicating that it is a new genus within the order; thus, a new combination is erected, Zirabia cylindrica. Conclusions: Our results indicate that Doyleales is significantly older than previously thought, with their stratigraphic range now extending from the Lower Jurassic to the Cretaceous. The Early Jurassic occurrence of Doyleales provides important data on the emergence of seed‐enclosing structures seen in seed plants throughout the Mesozoic. [ABSTRACT FROM AUTHOR]

This research aims to determine the quality of Scots pine (Pinus sylvestris L.) and Austrian pine (Pinus nigra Arnold) seed stands in Federation of Bosnia and Herzegovina, and to recommend measures for the improvement of these stan-ds for producing the highest quality reproduction material of the researched species. For this research, 23 traits of trees in fourteen seed stands of Scots pine, and twelve stands of Austrian pine in the Fe-deration of Bosnia and Herzegovina were analysed. Four traits were measured, and nineteen traits were assessed. The results have shown the good condition of seed stands of investigated traits for the most of investigated stands. Some of the stands have shown very good quality, and individual selection should be made in them, while in other stan-ds it is necessary to remove part of the trees. Considering the great ecological-vegetation diversity of Bosnia and Herzegovina, a greater number of Scots and Austri-an pine seed facilities is needed. When selecting new seed plants of white and black pine, the focus should be on small stands that grow in extreme conditions. [ABSTRACT FROM AUTHOR]

Over centuries of plant morphological research, biologists have enthusiastically explored how distinct vascular arrangements have diversified. These investigations have focused on the evolution of steles and secondary growth and examined the diversity of vascular tissues (xylem and phloem), including atypical developmental pathways generated through modifications to the typical development of ancestral ontogenies. A shared vernacular has evolved for communicating on the diversity of alternative ontogenies in seed plants. Botanists have traditionally used the term 'anomalous secondary growth' which was later renamed to 'cambial variants' by late Dr. Sherwin Carlquist (1988). However, the term 'cambial variants' can be vague in meaning since it is applied for developmental pathways that do not necessarily originate from cambial activity. Here, we review the 'cambial variants' concept and propose the term 'vascular variants' as a more inclusive overarching framework to interpret alternative vascular ontogenies in plants. In this framework, vascular variants are defined by their developmental origin (instead of anatomical patterns), allowing the classification of alternative vascular ontogenies into three categories: (i) procambial variants , (ii) cambial variants and (iii) ectopic cambia. Each category includes several anatomical patterns. Vascular variants, which represent broader developmental based groups, can be applied to both extant and fossil plants, and thereby offer a more adequate term from an evolutionary perspective. An overview of the developmental diversity and phylogenetic distribution of vascular variants across selected seed plants is provided. Finally, this viewpoint discusses the evolutionary implications of vascular variants. [ABSTRACT FROM AUTHOR]

Background Oriented patterning of epidermal cells is achieved primarily by transverse protodermal cell divisions perpendicular to the organ axis, followed by axial cell elongation. In linear leaves with parallel venation, most stomata are regularly aligned with the veins. This longitudinal patterning operates under a strong developmental constraint and has demonstrable physiological benefits, especially in grasses. However, transversely oriented stomata characterize a few groups, among both living angiosperms and extinct Mesozoic seed plants. Scope This review examines comparative and developmental data on stomatal patterning in a broad phylogenetic context, focusing on the evolutionary and ecophysiological significance of guard-cell orientation. It draws from a diverse range of literature to explore the pivotal roles of the plant growth hormone auxin in establishing polarity and chemical gradients that enable cellular differentiation. Conclusions Transverse stomata evolved iteratively in a few seed-plant groups during the Mesozoic era, especially among parasitic or xerophytic taxa, such as the hemiparasitic mistletoe genus Viscum and the xerophytic shrub Casuarina , indicating a possible link with ecological factors such as the Cretaceous CO2 decline and changing water availability. The discovery of this feature in some extinct seed-plant taxa known only from fossils could represent a useful phylogenetic marker. [ABSTRACT FROM AUTHOR]

Using the method of on-the-spot sample transect lines and plots survey a comprehensive investigation on the seed plants in the Qialong provincial nature reserve was conducted. The research shows: ① The reserve had a total of 957 species from 480-genera and 132 families. of wild seed plants, including 5 species from 5. genera and 3. families of gymosperms and 952 species from 475. genera and 129 families of angiosperms. The Life-form spectrum showed that the number of woody plants was lower than that of herbaceous plants, the evergreen component of woody plants was lower than that of deciduous components, and the proportion of trees was significantly lower, showing obvious characteristics of restorative vegetation. The distribution types at families level were mainly distributed in the world (43) and pan- tropical distribution (38).The ratio (R/TD of tropical to temperate was about 1.78. At genus level, the main distribution types were pan-tropical distribution (104) and worldwide distribution (55) . the ratio (R/T) of tropical to temperate was a- bout 1.07 and the tropical nature was slightly dominant showing the characteristics of transition from tropical nature to temperate nature. Comparison with neighboring protected areas revealed that the flora in Qiaoling has unity with that of eastern China showed an obvious subtropical mountain characteristics. reflecting the basic feature of the flora of the monsoon region in eastern China as a whole. Furthermore the results also indicated that the low mountain and hilly terrain was more conducive to the growth of plants with tropical nature. [ABSTRACT FROM AUTHOR]

Background: China is one of the most biodiverse countries in the world and has given birth to unique ecosystems, abundant species and rich genetic variety. More and more attention has been paid to biodiversity research in China. The Wanda Mountains, located in the east of Heilongjiang Province in northeast Chia, is a northern extension of the Changbai Mountains, one of the main mountains ranges in the region. In this study, we present the first checklist of spermatophyte and invasive alien plant species in the Wanda Mountains, which was compiled using published materials, specimen records and field surveys conducted from 2018 to 2020. This checklist, which has been published in the Global Biodiversity Information Facility (GBIF), provides a comprehensive overview of the plant species richness of the Wanda Mountains. New information: This data paper presents the first checklist of spermatophytes and invasive alien plants in the Wanda Mountains, comprising a total of 704 species and infraspecific taxa. Amongst these, there are 656 native plants belonging to 328 genera and 94 families and 48 invasive alien plants belonging to 39 genera and 20 families. The checklist includes 251 new records of native plants and 39 new records of invasive plants. This is the first widely shared data on an independent floristic unit in northeast China and can serve as a valuable resource for future biodiversity research in this region and, moreover, trigger more biodiversity data papers in this data-valued country. [ABSTRACT FROM AUTHOR]

Summary: The root system architecture in plants is a result of multiple evolutionary innovations over time in response to changing environmental cues. Dichotomy and endogenous lateral branching in the roots evolved in lycophytes lineage but extant seed plants use lateral branching instead. This has led to the development of complex and adaptive root systems, with lateral roots playing a key role in this process exhibiting conserved and divergent features in different plant species. The study of lateral root branching in diverse plant species can shed light on the orderly yet distinct nature of postembryonic organogenesis in plants. This insight provides an overview of the diversity in lateral root (LR) development in various plant species during the evolution of root system in plants. [ABSTRACT FROM AUTHOR]

Summary: The Cycadales are an ancient and charismatic group of seed plants. However, their morphological evolution in deep time is poorly understood. While molecular divergence time analyses estimate a Cretaceous origin for most major living cycad clades, much of the extant diversity is inferred to be a result of Neogene diversifications. This leads to long branches throughout the cycadalean phylogeny that, with few exceptions, have yet to be rectified by unequivocal fossil cycads.We report a permineralized pollen cone from the Campanian Holz Shale located in Silverado Canyon, CA, USA (c. 80 million yr ago). This fossil was studied via serial sectioning, SEM, 3D reconstruction and phylogenetic analyses.Microsporophyll and pollen morphology indicate this cone is assignable to Skyttegaardia, a recently described genus based on disarticulated lignitized microsporophylls from the Early Cretaceous of Denmark. Data from this new species, including a simple cone architecture, anatomical details and vasculature organization, indicate cycadalean affinities for Skyttegaardia. Phylogenetic analyses support this assignment and recover Skyttegaardia as crown‐group Cycadales, nested within Zamiaceae.Our findings support a Cretaceous diversification for crown‐group Zamiaceae, which included the evolution of morphological divergent extinct taxa with unique traits that have yet to be widely identified in the fossil record. [ABSTRACT FROM AUTHOR]

SUMMARY: Significant changes have occurred in plant cell wall composition during evolution and diversification of tracheophytes. As the sister lineage to seed plants, knowledge on the cell wall of ferns is key to track evolutionary changes across tracheophytes and to understand seed plant‐specific evolutionary innovations. Fern cell wall composition is not fully understood, including limited knowledge of glycoproteins such as the fern arabinogalactan proteins (AGPs). Here, we characterize the AGPs from the leptosporangiate fern genera Azolla, Salvinia, and Ceratopteris. The carbohydrate moiety of seed plant AGPs consists of a galactan backbone including mainly 1,3‐ and 1,3,6‐linked pyranosidic galactose, which is conserved across the investigated fern AGPs. Yet, unlike AGPs of angiosperms, those of ferns contained the unusual sugar 3‐O‐methylrhamnose. Besides terminal furanosidic arabinose, Ara (Araf), the main linkage type of Araf in the ferns was 1,2‐linked Araf, whereas in seed plants 1,5‐linked Araf is often dominating. Antibodies directed against carbohydrate epitopes of AGPs supported the structural differences between AGPs of ferns and seed plants. Comparison of AGP linkage types across the streptophyte lineage showed that angiosperms have rather conserved monosaccharide linkage types; by contrast bryophytes, ferns, and gymnosperms showed more variability. Phylogenetic analyses of glycosyltransferases involved in AGP biosynthesis and bioinformatic search for AGP protein backbones revealed a versatile genetic toolkit for AGP complexity in ferns. Our data reveal important differences across AGP diversity of which the functional significance is unknown. This diversity sheds light on the evolution of the hallmark feature of tracheophytes: their elaborate cell walls. [ABSTRACT FROM AUTHOR]

Aim: How spatial, historical and ecological processes drive diversity patterns remains one of the main foci of island biogeography. We determined how beta diversity varies across spatial scales and among organisms, disentangled the drivers of this variation, and examined how, consequently, biogeographic affinities within and among archipelagos vary among land plants. Location: Macaronesia. Taxon: Bryophytes, pteridophytes, spermatophytes. Methods: Species turnover and nestedness were compared within and among archipelagos across taxonomic groups. The relationship between species turnover and nestedness, climatic, geological and geographic factors was analysed using generalized dissimilarity models. Results: Species turnover, but not nestedness, increased with the geographic scale. This increment decreased from spermatophytes, pteridophytes and bryophytes, wherein the median turnover was less than half that in spermatophytes. Bryophytes exhibited a significantly higher nestedness and lower turnover than spermatophytes. Extant climatic conditions and island age contributed the most to all models but the importance of island age for bryophyte and pteridophyte turnover was marginal. Spermatophyte floras clustered by archipelago, whereas the clustering patterns in pteridophyte and bryophyte floras reflected macroclimatic conditions. Main Conclusions: The lower increment of species turnover with spatial scale and the higher nestedness in bryophytes and pteridophytes than in spermatophytes reflect the variation in dispersal capacities and distribution ranges among land plants. Accordingly, extant climatic conditions contributed more to explain turnover in bryophytes and pteridophytes than in spermatophytes, whereas factors associated with dispersal limitations, including island age, geographic distance and archipelago structure, exhibited the reverse trend. The differences in beta diversity patterns, caused by different responses of Macaronesian land plant lineages to the main factors shaping their community composition, explain their different biogeographic affinities. These differences reflect a distinct origin and different mechanisms of speciation among Macaronesian land plant lineages and archipelagos. [ABSTRACT FROM AUTHOR]

DNA barcode databases are increasingly available for a range of organisms, facilitating the wide application of DNA barcode‐based studies. Here we announce the development of a comprehensive DNA barcode reference library of Japanese native woody seed plants representing 43 orders, 99 families, 303 genera and 834 species, and comprising 77.3% of the genera and 72.2% of the species of native woody seed plants in Japan. A total of 6216 plant specimens were collected from 223 sites across the subtropical, temperate, boreal and alpine biomes in Japan with most species represented by multiple accessions. This reference library utilized three chloroplast DNA regions (rbcL, trnH‐psbA and matK) and consists of 14,403 barcode sequences. Individual regions varied in their identification rates, with species‐level and genus‐level rates for rbcL, trnH‐psbA and matK based on blast being 57.4%/96.2%, 78.5%/99.1% and 67.8%/98.1%, respectively. Identification rates were higher using region combinations, with total species‐level rates for two region combinations (rbcL & trnH‐psbA, rbcL & matK and trnH‐psbA & matK) ranging between 90.6% and 95.8%, and for all three regions being equal to 98.6%. Genus‐level identification rates were even higher, ranging between 99.7% and 100% for two region combinations and being 100% for the three regions. These results indicate that this DNA barcode reference library is an effective resource for investigations of native woody seed plants in Japan using DNA barcodes and provides a useful template for the development of libraries for other components of the Japanese flora. [ABSTRACT FROM AUTHOR]

Eumaeus butterflies are obligate herbivores of Zamia, the most diverse neotropical genus of cycads. Eumaeus–Zamia interactions have been characterized mainly for species distributed in North and Central America. However, larval host plant use by the southern Eumaeus clade remains largely unknown, precluding a comprehensive study of co‐evolution between the genera. Here, we combine fieldwork with museum and literature surveys to expand herbivory records for Eumaeus from 21 to 38 Zamia species. We inferred a time‐calibrated phylogeny of Eumaeus to test for distinct macroevolutionary scenarios of larval host plant conservatism and co‐evolution. We found a remarkable coincidence between Eumaeus and Zamia diversification, with the butterfly stem group diverging at the same time as the most recent radiation of Zamia in the Miocene. Cophylogenetic reconciliation analyses show a strong cophylogenetic signal between cycads and their butterfly herbivores. Bipartite model‐based approaches indicate that this is because closely related Zamia species are used by the same Eumaeus species, suggesting larval host plant resource tracking by the butterfly herbivores. Our results highlight a case of tight evolution between Eumaeus butterflies and cycads, pointing to the generality of correlated evolution and phylogenetic tracking in plant–herbivore interactions across seed plants. [ABSTRACT FROM AUTHOR]

This article considers the technology of reproduction by monitoring the phytocenotic features, biomorphological and eco-biological conditions of saxaul in the southern region of Kazakhstan. As an environmental issue, the state of saxaul production in the southern regions of Kazakhstan is still not up to date. This is due to the lack of scientifically based agro technology for growing saxaul crops in the wild, the lack of forest seed base and special seeders for sowing saxaul seeds. Therefore, it is necessary to evaluate the existing cultivation technologies and reconsider the idea of saxaul as a plant that can grow in any forest conditions. The research was carried out in the laboratory conditions of the Department of Ecology and Chemistry of the Faculty of Natural Sciences. Geobotanical methods and agrotechnical research methods were used as scientific methods: control of seed planting material of black saxaul. For comparison with wild saxaul species, the expeditionary method, latent, virginal and generative development methods, control methods, and phenological research methods were used. Studies have shown that saxaul seeds can be grown in artificial and field conditions. As a result of the study, it can be predicted that the southern region has the opportunity to increase the number and scale of saxaul species. This fact provides a favorable ecological solution to the environment, that is, the problem of desertification and sand control. The seeds of the black saxaul were planted in laboratory conditions before the seedlings were ready to be transplanted into the natural area. [ABSTRACT FROM AUTHOR]

Plants have evolved a remarkable capacity to develop new organs post-embryonically throughout their lifespan. A prime example of this is root branching. Root branching occurs in two ways: dichotomous and lateral branching. The dichotomous branching is the result of the division of the root apical meristem into two daughter meristems, likely through symmetric cell divisions of the root apical cell, as has recently been illustrated in the extant lycophyte Selaginella moellendorffii (Figure 1). Lateral root branching relies on the de novo specification of a subset of founder cells (hereinafter referred to as lateral root stem cells) located in the internal tissues of an existing root. This step is followed by initiation, in which the specified cells re-enter the cell cycle, and subsequently by primordium formation and emergence. In this primer, we summarize recent advances describing the molecular bases underlying lateral root stem cell specification in angiosperms and highlight the important positional signals that fine tune this process. By delving into the evolutionary origins of root branching, we point out that positional control of lateral root stem cell specification has not been the prevailing mechanism among all plants and discuss the process in ferns (i.e., a sister group of seed plants), where it seems to be under the control of lineage-dependent mechanisms. Lakehal et al. discuss the specification and evolutionary origins of lateral roots. [ABSTRACT FROM AUTHOR]

Increased access to genome‐wide data provides new opportunities for plant conservation. However, information on neutral genetic diversity in a small number of marker loci can still be valuable because genomic data are not available to most rare plant species. In the hope of bridging the gap between conservation science and practice, we outline how conservation practitioners can more efficiently employ population genetic information in plant conservation. We first review the current knowledge about neutral genetic variation (NGV) and adaptive genetic variation (AGV) in seed plants, regarding both within‐population and among‐population components. We then introduce the estimates of among‐population genetic differentiation in quantitative traits (QST) and neutral markers (FST) to plant biology and summarize conservation applications derived from QST–FST comparisons, particularly on how to capture most AGV and NGV on both in‐situ and ex‐situ programs. Based on a review of published studies, we found that, on average, two and four populations would be needed for woody perennials (n = 18) to capture 99% of NGV and AGV, respectively, whereas four populations would be needed in case of herbaceous perennials (n = 14). On average, QST is about 3.6, 1.5, and 1.1 times greater than FST in woody plants, annuals, and herbaceous perennials, respectively. Hence, conservation and management policies or suggestions based solely on inference on FST could be misleading, particularly in woody species. To maximize the preservation of the maximum levels of both AGV and NGV, we suggest using maximum QST rather than average QST. We recommend conservation managers and practitioners consider this when formulating further conservation and restoration plans for plant species, particularly woody species. [ABSTRACT FROM AUTHOR]

Most seed plants produce both pollen and ovules. In principle, pollen export could interfere with pollen import through self‐pollination, resulting in ovule usurpation and reduced fruit set. Evidence for such interference exists under experimental settings but its importance under natural conditions is unknown. To test for sexual interference in nature, it is necessary to study together mating system, through paternity analyses, and fruit set, the proportion of flowers giving seeds or fruits. We developed a new model combining both processes, using chestnut (Castanea) as case study. We carried out a paternity analysis in an intensively studied plot of 273 trees belonging to three interfertile chestnut species and including a range of individuals with more or less functional stamens, resulting in a large data set of 1924 mating events. We then measured fruit set on 216 of these trees. Fruit set of male‐fertile trees was much lower than that of male‐sterile trees. Our process‐based model shows that pollen is not limiting in the study site and hence cannot account for reduced fruit set. It also indicates that self‐pollination is high (74%) but selfing rate is low (4%). Self‐pollen is less competitive than cross‐pollen, reducing sexual interference, but not sufficiently, as many ovules end up being self‐fertilized, 95% of which abort before fruit formation, resulting in the loss of 46% of the fruit crop. These results suggest that the main cause of reduced reproductive potential in chestnut is sexual interference by self‐pollen, raising questions on its evolutionary origins. [ABSTRACT FROM AUTHOR]

During their postembryonic development, plants continuously form branches to conquer more space and adapt to changing environments. In seed plants, this is achieved by lateral branching, in which axillary meristems (AMs) initiate at the leaf axils to form axillary buds. The developmental potential of AMs to form shoot branches is the same as that of embryonic shoot apical meristems (SAMs). Recent studies in Arabidopsis thaliana have revealed the cellular origin of AMs and have identified transcription factors and phytohormones that regulate sequential steps leading to AM initiation. In particular, a group of meristematic cells detached from the SAM are key to AM initiation, which constitutes an excellent system for understanding stem cell fate and de novo meristem formation. [ABSTRACT FROM AUTHOR]

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The gaseous hormone ethylene plays a pivotal role in plant growth and development. In seed plants, the key rate-limiting enzyme that controls ethylene biosynthesis is ACC synthase (ACS). ACS has, for a long time, been believed to be a single-activity enzyme until we recently discovered that it also possesses Cβ-S lyase (CSL) activity. This discovery raises fundamental questions regarding the biological significance of the dual enzymatic activities of ACS. To address these issues, it is highly necessary to obtain ACS mutants with either ACS or CSL single activity. Here, domain swapping between Arabidopsis AtACS7 and moss CSL PpACL1 were performed. Enzymatic activity assays of the constructed chimeras revealed that, R10, which was produced by replacing AtACS7 box 6 with that of PpACL1, lost ACS but retained CSL activity, whereas R12 generated by box 4 substitution lost CSL and only had ACS activity. The activities of both chimeric proteins were compared with previously obtained single-activity mutants including R6, AtACS7Q98A, and AtACS7D245N. All the results provided new insights into the key residues required for ACS and CSL activities of AtACS7 and laid an important foundation for further in-depth study of the biological functions of its dual enzymatic activities. [ABSTRACT FROM AUTHOR]

Aspartic proteases are widely distributed in animals, plants, fungi and other organisms. In land plants, A1 aspartic protease family members have been implicated to play important and varied roles in growth, development and defense. Thus a robust classification of this family is important for understanding their gene function and evolution. However, current A1 family members in Arabidopsis are less well classified and need to be re-evaluated. In this paper, 70 A1 aspartic proteases in Arabidopsis are divided into four groups (group I-IV) based on phylogenetic and gene structure analyses of 1200 A1 aspartic proteases which are obtained from 12 Embryophyta species. Group I-III members are further classified into 2, 4 and 7 subgroups based on the AlphaFold predicted structures. Furthermore, unique insights of A1 aspartic proteases have been unraveled by AlphaFold predicted structures. For example, subgroup II-C members have a unique II-C specific motif in the C-extend domain, and subgroup IV is a Spermatophyta conserved group without canonical DTGS/DSGT active sites. These results prove that AlphaFold combining phylogenetic analysis is a promising solution for complex gene family classification. [ABSTRACT FROM AUTHOR]

Background: Flavonoids are specialized metabolites with numerous biological functions in stress response and reproduction of plants. Flavones are one subgroup that is produced by the flavone synthase (FNS). Two distinct enzyme families evolved that can catalyze the biosynthesis of flavones. While the membrane-bound FNS II is widely distributed in seed plants, one lineage of soluble FNS I appeared to be unique to Apiaceae species. Results: We show through phylogenetic and comparative genomic analyses that Apiaceae FNS I evolved through tandem gene duplication of flavanone 3-hydroxylase (F3H) followed by neofunctionalization. Currently available datasets suggest that this event happened within the Apiaceae in a common ancestor of Daucus carota and Apium graveolens. The results also support previous findings that FNS I in the Apiaceae evolved independent of FNS I in other plant species. Conclusion: We validated a long standing hypothesis about the evolution of Apiaceae FNS I and predicted the phylogenetic position of this event. Our results explain how an Apiaceae-specific FNS I lineage evolved and confirm independence from other FNS I lineages reported in non-Apiaceae species. [ABSTRACT FROM AUTHOR]

N‐terminal cysteine oxidases (NCOs) use molecular oxygen to oxidise the amino‐terminal cysteine of specific proteins, thereby initiating the proteolytic N‐degron pathway. To expand the characterisation of the plant family of NCOs (plant cysteine oxidases [PCOs]), we performed a phylogenetic analysis across different taxa in terms of sequence similarity and transcriptional regulation. Based on this survey, we propose a distinction of PCOs into two main groups. A‐type PCOs are conserved across all plant species and are generally unaffected at the messenger RNA level by oxygen availability. Instead, B‐type PCOs appeared in spermatophytes to acquire transcriptional regulation in response to hypoxia. The inactivation of two A‐type PCOs in Arabidopsis thaliana, PCO4 and PCO5, is sufficient to activate the anaerobic response in young seedlings, whereas the additional removal of B‐type PCOs leads to a stronger induction of anaerobic genes and impairs plant growth and development. Our results show that both PCO types are required to regulate the anaerobic response in angiosperms. Therefore, while it is possible to distinguish two clades within the PCO family, we conclude that they all contribute to restrain the anaerobic transcriptional programme in normoxic conditions and together generate a molecular switch to toggle the hypoxic response. Summary statement: Hypoxic induction of plant cysteine oxidases has been acquired and fixed in seed plants from ancestral proteins able to initiate the proteolysis of Cys‐initiating protein substrates by the Arg/N‐degron pathway. [ABSTRACT FROM AUTHOR]

Premise: Rhizomatous growth characterizes numerous taxa among vascular plants. While abundant information exists on nutrient sharing and demography, the question of how these metameric organisms move water through their bodies remains largely unstudied. Moreover, we lack an understanding of the evolutionary implications of rhizomatous growth across vascular plants. Here, we examined these questions by investigating how rhizomatous growth and vascular construction affect whole‐plant hydraulic function. Methods: In five terrestrial fern species with diverse vascular construction, we used microcomputed tomography and bright‐field microscopy to examine vascular construction across nodes along the rhizome. These data were integrated with measurements of leaf stomatal conductance under rooted and uprooted conditions to relate vascular patterning and hydraulic architecture to leaf water status. Results: Similar to phytomers of woody seed plants, nodal regions in rhizomatous ferns are areas of hydraulic resistance. While water is shared along the rhizomes of these investigated species, hydraulic conductivity drops at nodes and stomatal conductance declines when nodes were locally uprooted. Together, our data suggest that nodes are chokepoints in axial water movement along the rhizome. Conclusions: Nodal chokepoints decrease hydraulic integration between phytomers. At the same time, chokepoints may act as "safety valves", hydraulically localizing each phytomer—potentially decreasing embolism and pathogen spread. This suggests a potential trade‐off in the principal construction of the fern rhizome. Moreover, we propose that shoot‐borne roots (homorhizy) and the prostrate habit of rhizomatous ferns decrease the hydraulic and structural burdens that upright plants typically incur. The absence of these hydraulic and structural demands may be one reason ferns (and many rhizomatous plants) lack, or have minimally developed, secondary xylem. [ABSTRACT FROM AUTHOR]

Premise: Trimerophytes are a plexus of early tracheophytes that form the base of the euphyllophyte clade and, thus, represent the link between the earliest land plants and modern‐day ferns, sphenophytes, and seed plants. As the best‐characterized trimerophyte, the genus Psilophyton occupies a key position in the euphyllophyte fossil record. We describe a new Psilophyton species that has implications for the evolution of plant–animal interactions. Methods: The fossil material is preserved by permineralization in the Lower Devonian (Emsian) Battery Point Formation (Québec, Canada) and was studied in serial sections using the cellulose acetate peel technique. Results: Psilophyton diakanthon sp. nov. differs from other Psilophyton species in possessing fibers that form a discontinuous layer in the inner cortex and two distinct types of spinescent emergences whose anatomy and morphology are consistent with roles in anti‐herbivore defense. Conclusions: Psilophyton diakanthon adds another species to an already diverse genus. Its two morphologically distinct types of spinescence suggest that herbivory was rampant in plant–animal interactions and demonstrate that anti‐herbivory defenses had reached a previously unrecognized level of sophistication by 400 million years ago, in the Early Devonian. [ABSTRACT FROM AUTHOR]

Copyright of Nova Acta Científica Compostelana is the property of Universidad de Santiago de Compostela, Servicio de Publicaciones and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mt. Pantaron Range has no legislation for its protection and has significantly lost most of its forest cover over the years due to land conversion for agriculture and human settlement, construction of national highways, and illegal logging and mining. Floristic inventory was conducted in four sampling sites in Mt. Pantaron Range, Bukidnon to document its threatened and endemic seed plants through repeated transect walks. A total of 133 threatened and endemic species of seed plants were documented. Of these, 41 species were threatened, and 120 were endemic species. Mt. Bungkasan, Pantaron Range harbors 70 (52.6%) species of threatened and endemic seed plants, followed by Mt. Malimumu with 53 (40%) species, Mt. Natampod with 40 (30%) species, and Mt. Nabagkesan with only 19 (14%) species. The checklist of threatened seed plants reported herein represents 4.3% of the threatened seed plants and 2.6% of the endemic seed plants in the Philippines. Site comparisons using Bray-Curtis cluster analysis in terms of threatened and endemic species composition are relatively low (≤ 33%), implying the uniqueness of the species for each site in the said mountain range. The assemblage of threatened and endemic seed plants in Mt. Pantaron Range calls for immediate conservation endeavors by the stakeholders to warrant the protection of its threatened and endemic seed plants. [ABSTRACT FROM AUTHOR]

This paper analyses and describes the benthic foraminiferal associations within the Pleistocene deposits of the Stirone River (Emilia-Romagna, Italy), with the purpose of testing foraminifera as Indirect Palaeo-Seagrass Indicators (IPSIs). Our analyses focused on two different biofacies: a Thalassinoides biofacies, characterised by an oligotypic biotic assemblage and a Pinna biofacies representing an infralittoral soft bottom colonised by marine phanerogams and characterized by high biodiversity. To strengthen the analyses, we have compared the Stirone foraminiferal association with the one of Fauglia (Tuscany, Italy), in which a well-preserved, early Pleistocene, fossil Posidonia meadow, is present. The aim of this work is to provide qualitative and quantitative parameters that can be used to recognize past vegetated environments, where fossil seagrass are no longer present. Considering the influence of ecological constraints and diagenetic processes on the foraminiferal assemblages, several indexes such as the Index EP , the modified FORAM index (FI'), the "long vs. short life-span index" (I LS), and the K/R EXT (keeled/rounded morphotypes) have been calculated and a morphotype-based analysis has been provided. Among the tested indexes, the latter proved to be the most reliable IPSI, in association with the presence of morphotype A*, permanently attached, encrusting foraminifera and the abundance of Rosalinidae. [ABSTRACT FROM AUTHOR]

The group referred to informally as the corystosperms, described initially based on compression fossils from the Triassic of Gondwana, have long been considered critical extinct plants for understanding seed plant phylogeny, the evolution of seed plant reproductive structures and the relationships of angiosperms. Here we describe a new genus and species of corystosperm seed-bearing structure, Jarudia zhoui gen. et sp. nov., based on abundant silicified material collected from the newly discovered chert in the Early Cretaceous Huolinhe Formation of eastern Inner Mongolia, north-eastern China. Jarudia zhoui is a lax seed cone consisting of a flexible central axis bearing deciduous, helically arranged, lateral seed-bearing units. Individual seed-bearing units consist of an elongate bract partially fused to an unbranched cupule stalk that bears a single, reflexed cupule apically. Each cupule is formed by the strongly reflexed cupule stalk and one median and two lateral flaps. The cupule stalk supplied by two vascular bundles and three unvascularized flaps partially enclose two three-angled seeds. Jarudia zhoui bears a striking resemblance to Doylea tetrahedrasperma from the Early Cretaceous of Canada and similar plants from the Early Cretaceous of Mongolia. There are also strong similarities with ovulate structures of Umkomasia from the Triassic of Gondwana in the structure and anatomy of individual cupules, their axial nature, and the architecture of the entire seed-bearing structure that has two orders of branching. New information from Jarudia zhoui, together with information on other corystosperm ovulate organs from the Northern Hemisphere, significantly expands our understanding of this key group of extinct plants, suggests that the cupules of the Early Cretaceous and Triassic corystosperms are homologous, and raises critical questions about the definition and phylogenetic circumscription of the corystosperms, including how Early Cretaceous and Triassic corystosperms are related to each other and to other groups of seed plants, including angiosperms. [ABSTRACT FROM AUTHOR]

Copyright of Adiyaman University Journal of Science & Technology / Adıyaman Üniversitesi Fen Bilimleri Dergisi is the property of Adiyaman University, Institute of Science / Adiyaman Universitesi Fen Bilimleri Enstitusu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Current and previous studies have extensively studied the physiological and ecological consequences of genome size (GS) on plants because of the limiting effect of GS on cell size. However, it is still obscure whether such limiting effect could be shifted by environmental pressures, or not. Here, we compiled a global dataset comprised of GS, xylem vessel diameter (Vdia), xylem hydraulic conductivity (KS), P50 (xylem water potential at the loss of 50% maximum KS), and climate factors of 251 phylogeny and habitat divergent species from 59 families. The results showed that GS could limit the Vdia of the species from the same family sampled in the similar climate conditions. But the expected positive relationship between GS and Vdia became uncertain and even negative across different environmental conditions. Vdia was strongly positively coordinated with mean annual temperature (MAT), mean annual precipitation (MAP), and potential evapotranspiration (PET). Furthermore, Vdia as the anatomic foundation of plant hydraulic performance was strongly positively coordinated with KS and negatively coordinated with −P50. The strong environmental selection on KS and P50 explained the concerted regulation of Vdia by environmental factors. The findings revealed the combined regulation of GS and environmental pressures on xylem cell size and thus affected plant eco‐physiological performance. The shifted cell size limiting effect of GS by environmental factors manifests plants great plasticity under changed environmental conditions. [ABSTRACT FROM AUTHOR]

The stem is one of the major organs in seed plants and is important for plant survival as well as in agriculture. However, due to the lack of clear external landmarks in many species, its developmental and evolutionary processes are understudied compared to other organs. Recent approaches tackling these problems, especially those focused on KNOX1 and BLH transcription factors belonging to the TALE homeodomain superfamily have started unveiling the patterning process of nodes and internodes by connecting previously accumulated knowledge on lateral organ regulators. Fossil records played crucial roles in understanding the evolutionary process of the stem. The aim of this review is to introduce how the stem evolved from ancestorial sporophyte axes and to provide frameworks for future efforts in understanding the developmental process of this elusive but pivotal organ. [ABSTRACT FROM AUTHOR]

Tonoplast intrinsic proteins (TIPs) are crucial in facilitating the transportation of water and various small solutes across biological membranes. The evolutionary path and functional roles of TIPs is poorly understood in plants. In the present study, a total of 976 TIPs were identified in 104 diverse species and subsequently studied to trace their lineage-specific evolutionary path and tissue-specific function. Interestingly, TIPs were found to be absent in lower forms such as algae and fungi and they evolved later in primitive plants like bryophytes. Bryophytes possess a distant class of TIPs, denoted as TIP6, which is not found in higher plants. The aromatic/arginine (ar/R) selectivity filter found in TIP6 of certain liverworts share similarity with hybrid intrinsic protein (HIP), suggesting an evolutionary kinship. As plants evolved to more advanced forms, TIPs diversified into five different sub-groups (TIP1 to TIP5). Notably, TIP5 is a sub-group unique to angiosperms. The evolutionary history of the TIP subfamily reveals an interesting observation that the TIP3 subgroup has evolved within seed-bearing Spermatophyta. Further, TIPs exhibit tissue-specific expression that is conserved within various plant species. Specifically, the TIP3s were found to be exclusively expressed in seeds. Quantitative PCR analysis of TIP3s showed gradually increasing expression in soybean seed developmental stages. The expression of TIP3s in different plant species was also found to be gradually increasing during seed maturation. The results presented here address the knowledge gap concerning the evolutionary background of TIPs, specifically TIP3 in plants, and provide valuable insights for a deeper comprehension of the functions of TIPs in plants. • Tonoplast intrinsic proteins (TIPs) evolved initially in Bryophytes. • Subgroup TIP5 observed only in angiosperms and TIP3 in seed-bearing Spermatophyta. • TIPs exhibit tissue-specific expression that is conserved across various plant species. • TIP3 genes were found to be exclusively expressed in seeds. [ABSTRACT FROM AUTHOR]

Most retrograde signalling research in plants was performed using Arabidopsis, so an evolutionary perspective on mitochondrial retrograde regulation (MRR) is largely missing. Here, we used phylogenetics to track the evolutionary origins of factors involved in plant MRR. In all cases, the gene families can be traced to ancestral green algae or earlier. However, the specific subfamilies containing factors involved in plant MRR in many cases arose during the transition to land. NAC transcription factors with C-terminal transmembrane domains, as observed in the key regulator ANAC017, can first be observed in non-vascular mosses, and close homologs to ANAC017 can be found in seed plants. Cyclin-dependent kinases (CDKs) are common to eukaryotes, but E-type CDKs that control MRR also diverged in conjunction with plant colonization of land. AtWRKY15 can be traced to the earliest land plants, while AtWRKY40 only arose in angiosperms and AtWRKY63 even more recently in Brassicaceae. Apetala 2 (AP2) transcription factors are traceable to algae, but the ABI4 type again only appeared in seed plants. This strongly suggests that the transition to land was a major driver for developing plant MRR pathways, while additional fine-tuning events have appeared in seed plants or later. Finally, we discuss how MRR may have contributed to meeting the specific challenges that early land plants faced during terrestrialization. [ABSTRACT FROM AUTHOR]

The origins and evolution of the outstanding Neotropical biodiversity are a matter of intense debate. A comprehensive understanding is hindered by the lack of deep-time comparative data across wide phylogenetic and ecological contexts. Here, we quantify the prevailing diversification trajectories and drivers of Neotropical diversification in a sample of 150 phylogenies (12,512 species) of seed plants and tetrapods, and assess their variation across Neotropical regions and taxa. Analyses indicate that Neotropical diversity has mostly expanded through time (70% of the clades), while scenarios of saturated and declining diversity account for 21% and 9% of Neotropical diversity, respectively. Five biogeographic areas are identified as distinctive units of long-term Neotropical evolution, including Pan-Amazonia, the Dry Diagonal, and Bahama-Antilles. Diversification dynamics do not differ across these areas, suggesting no geographic structure in long-term Neotropical diversification. In contrast, diversification dynamics differ across taxa: plant diversity mostly expanded through time (88%), while a substantial fraction (43%) of tetrapod diversity accumulated at a slower pace or declined towards the present. These opposite evolutionary patterns may reflect different capacities for plants and tetrapods to cope with past climate changes. [ABSTRACT FROM AUTHOR]

The Qinling-Daba Mountains span subtropical and warm temperate zones and are one of the most remarkable biodiversity hotspots in China. Establishing a complete checklist of seed plants organized by nature reserves in the Qinling-Daba Mountains and adjacent areas is an important basis for managing and utilizing plant resources. First, we collected seed plant species data from published checklists representing 58 nature reserves in the Qinling-Daba Mountains and adjacent areas; second, we comprehensively and systematically sorted and integrated these data; third, we proofread and revised the data with the help of the R language and Flora of China dataset; and finally, we set up a seed plant database containing 96148 records, including the name, order, family, genus, life form, and endemism of each species for the entirety of the Qinling-Daba Mountains. The database contains 9491 species of seed plants belonging to 1729 genera, 211 families, and 59 orders, accounting for 39% of China's seed plants. Measurement(s) seed plants on taxonomy, geography and ecology Technology Type(s) literature search, data extraction and structure Sample Characteristic - Organism Spermatophyta Sample Characteristic - Environment mountain range Sample Characteristic - Location Qinling Mountains • Daba Mountains [ABSTRACT FROM AUTHOR]

The plant economics spectrum describes the trade‐off between plant resource acquisition and storage, and sheds light on plant responses to environmental changes. However, the data used to construct the plant economics spectrum comes mainly from seed plants, thereby neglecting vascular non‐seed plant lineages such as the ferns. To address this omission, we evaluated whether a fern economics spectrum exists using leaf and root traits of 23 fern species living under three subtropical forest conditions differing in light intensity and nutrient gradients. The fern leaf and root traits were found to be highly correlated and formed a plant economics spectrum. Specific leaf mass and root tissue density were found to be on one side of the spectrum (conservative strategy), whereas photosynthesis rate, specific root area, and specific root length were on the other side of the spectrum (acquisitive strategy). Ferns had higher photosynthesis and respiration rates, and photosynthetic nitrogen‐use efficiency under high light conditions and higher specific root area and lower root tissue density in high nutrient environments. However, environmental changes did not significantly affect their resource acquisition strategies. Thus, the plant economics spectrum can be broadened to include ferns, which expands its phylogenetic and ecological implications and utility. [ABSTRACT FROM AUTHOR]

Background and Aims Cycads are regarded as an ancient lineage of living seed plants, and hold important clues to understand the early evolutionary trends of seed plants. The molecular phylogeny and spatio-temporal diversification of one of the species-rich genera of cycads, Macrozamia , have not been well reconstructed. Methods We analysed a transcriptome dataset of 4740 single-copy nuclear genes (SCGs) of 39 Macrozamia species and two outgroup taxa. Based on concatenated (maximum parsimony, maximum likelihood) and multispecies coalescent analyses, we first establish a well-resolved phylogenetic tree of Macrozamia. To identify cyto-nuclear incongruence, the plastid protein coding genes (PCGs) from transcriptome data are extracted using the software HybPiper. Furthermore, we explore the biogeographical history of the genus and shed light on the pattern of floristic exchange between three distinct areas of Australia. Six key diagnostic characters are traced on the phylogenetic framework using two comparative methods, and infra-generic classification is investigated. Key Results The tree topologies of concatenated and multi-species coalescent analyses of SCGs are mostly congruent with a few conflicting nodes, while those from plastid PCGs show poorly supported relationships. The genus contains three major clades that correspond to their distinct distributional areas in Australia. The crown group of Macrozamia is estimated to around 11.80 Ma, with a major expansion in the last 5–6 Myr. Six morphological characters show homoplasy, and the traditional phenetic sectional division of the genus is inconsistent with this current phylogeny. Conclusions This first detailed phylogenetic investigation of Macrozamia demonstrates promising prospects of SCGs in resolving phylogenetic relationships within cycads. Our study suggests that Macrozamia , once widely distributed in Australia, underwent major extinctions because of fluctuating climatic conditions such as cooling and mesic biome disappearance in the past. The current close placement of morphologically distinct species in the phylogenetic tree may be related to neotenic events that occurred in the genus. [ABSTRACT FROM AUTHOR]

Plant respiratory burst oxidase homologs (RBOHs) are plasma membranelocalized NADPH oxidases that generate superoxide anion radicals, which then dismutate to H2O2, into the apoplast using cytoplasmic NADPH as an electron donor. PaRBOH1 is the most highly expressed RBOH gene in developing xylem as well as in a lignin-forming cell culture of Norway spruce (Picea abies L. Karst.). Since no previous information about regulation of gymnosperm RBOHs exist, our aim was to resolve how PaRBOH1 is regulated with a focus on phosphorylation. The N-terminal part of PaRBOH1 was found to contain several putative phosphorylation sites and a four-times repeated motif with similarities to the Botrytis-induced kinase 1 target site in Arabidopsis AtRBOHD. Phosphorylation was indicated for six of the sites in in vitro kinase assays using 15 amino-acid-long peptides for each of the predicted phosphotarget site in the presence of protein extracts of developing xylem. Serine and threonine residues showing positive response in the peptide assays were individually mutated to alanine (kinase-inactive) or to aspartate (phosphomimic), and the wild type PaRBOH1 and the mutated constructs transfected to human kidney embryogenic (HEK293T) cells with a low endogenous level of extracellular ROS production. ROS-producing assays with HEK cells showed that Ca2+ and phosphorylation synergistically activate the enzyme and identified several serine and threonine residues that are likely to be phosphorylated including a novel phosphorylation site not characterized in other plant species. These were further investigated with a phosphoproteomic study. Results of Norway spruce, the first gymnosperm species studied in relation to RBOH regulation, show that regulation of RBOH activity is conserved among seed plants. [ABSTRACT FROM AUTHOR]

Speciation is driven by the evolution of reproductive isolating barriers that reduce, and ultimately prevent, substantial gene flow between lineages. Despite its central role in evolutionary biology, the process can be difficult to study because it proceeds differently among groups and may occur over long timescales. Due to this complexity, we typically rely on generalizations of empirical data to describe and understand the process. Previous reviews of reproductive isolation (RI) in flowering plants have suggested that prezygotic or extrinsic barriers generally have a stronger effect on reducing gene flow compared to postzygotic or intrinsic barriers. Past conclusions have rested on relatively few empirical estimates of RI; however, RI data have become increasingly abundant over the past 15 years. We analyzed data from recent studies quantifying multiple pre‐ and postmating barriers in plants and compared the strengths of isolating barriers across 89 taxa pairs using standardized RI metrics. Individual prezygotic barriers were on average stronger than individual postzygotic barriers, and the total strength of prezygotic RI was approximately twice that of postzygotic RI. These findings corroborate that ecological divergence and extrinsic factors, as opposed to solely the accumulation of genetic incompatibilities, are important to speciation and the maintenance of species boundaries in plants. Despite an emphasis in the literature on asymmetric postmating and postzygotic RI, we found that prezygotic barriers acted equally asymmetrically. Overall, substantial variability in the strengths of 12 isolating barriers highlights the great diversity of mechanisms that contribute to plant diversification. [ABSTRACT FROM AUTHOR]

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Plastids are one of the main distinguishing characteristics of the plant cell. The plastid genome (plastome) of most autotrophic seed plants possesses a highly conserved quadripartite structure containing a large single-copy (LSC) and a small single-copy (SSC) region separated by two copies of the inverted repeat (termed as IRA and IRB). The IRs have been inferred to stabilize the plastid genome via homologous recombination-induced repair mechanisms. IR loss has been documented in seven autotrophic flowering plant lineages and two autotrophic gymnosperm lineages, and the plastomes of these species (with a few exceptions) are rearranged to a great extent. However, some plastomes containing normal IRs also show high structural variation. Therefore, the role of IRs in maintaining plastome stability is still controversial. In this study, we first integrated and compared genome structure and sequence evolution of representative plastomes of all nine reported IR-lacking lineages and those of their closest relative(s) with canonical inverted repeats (CRCIRs for short) to explore the role of the IR in maintaining plastome structural stability and sequence evolution. We found the plastomes of most IR-lacking lineages have experienced significant structural rearrangement, gene loss and duplication, accumulation of novel small repeats, and acceleration of synonymous substitution compared with those of their CRCIRs. However, the IR-lacking plastomes show similar structural variation and sequence evolution rate, and even less rearrangement distance, dispersed repeat number, tandem repeat number, indels frequency and GC3 content than those of IR-present plastomes with variation in Geraniaceae. We argue that IR loss is not a driver of these changes but is instead itself a consequence of other processes that more broadly shape both structural and sequence-level plastome evolution. [ABSTRACT FROM AUTHOR]

Plants produce the volatile hormone ethylene to regulatemany developmental processes and to deal with (a)biotic stressors. In seed plants, ethylene is synthesized from 1-aminocyclopropane-1-carboxylic acid (ACC) by the dedicated enzyme ACC oxidase (ACO). Ethylene biosynthesis is tightly regulated at the level of ACC through ACC synthesis, conjugation and transport. ACC is a non-proteinogenic amino acid, which also has signaling roles independent from ethylene. In this work, we investigated the biological function of an uncharacterized ACC dipeptide. The custom-synthesized di-ACCmolecule can be taken up by Arabidopsis in a similar way as ACC, in part via Lysine Histidine Transporters (e.g., LHT1). Using Nano-Particle Assisted Laser Desoprtion/Ionization (Nano-PALDI)mass-spectrometry imaging, we revealed that externally fed di-ACC predominantly localizes to the vasculature tissue, despite it not being detectable in control hypocotyl segments. Once taken up, the ACC dimer can evoke a triple response phenotype in dark-grown seedlings, reminiscent of ethylene responses induced by ACC itself, albeit less efficiently compared to ACC. Di-ACC does not act via ACC-signaling, but operates via the known ethylene signaling pathway. In vitro ACOactivity andmolecular docking showed that di-ACC can be used as an alternative substrate by ACO to form ethylene. The promiscuous nature of ACO for the ACC dimer also explains the higher ethylene production rates observed in planta, although this reaction occurred less efficiently compared to ACC. Overall, the ACC dipeptide seems to be transported and converted into ethylene in a similar way as ACC, and is able to augment ethylene production levels and induce subsequent ethylene responses in Arabidopsis. [ABSTRACT FROM AUTHOR]

The delivery of sperm cells via tip‐growing pollen tubes is an innovation of seed plants and shows the importance of pollen tubes for reproduction and their specific growth kinetics. Fast‐growing pollen tubes demand an extensive and dynamic vesicular trafficking network to build new cell membrane and wall, to deliver proteins among endomembrane compartments, and also to respond to external stimuli for growth adjustment. In this review, we summarize current findings on endomembrane compartments and vesicular trafficking routes of pollen tubes, comparing and contrasting their features with those of most somatic cells. We discuss the importance of membrane homeostasis, either at the plasma membrane (PM) or between PM‐targeted trafficking and vacuolar trafficking, for pollen tube growth. We also provide perspectives to facilitate future studies of vesicular trafficking in pollen tubes. [ABSTRACT FROM AUTHOR]

TCP proteins are plant-specific transcription factors, which are involved in a broad range of physiological processes of plant growth and development. However, the origin and evolutionary history of this gene family is not fully resolved. Here, we present a genome-wide survey of TCP genes in 59 species (including 42 genomes and 17 transcriptomes) covering all main lineages of green plants, and reconstruct the evolutionary history of this gene family. Our results suggested that the origin of TCP genes predated the emergence of land plants, possibly in the common ancestor of Phragmoplastophyta. The TCP gene family gradually experienced a continuous expansion and grew from a few members in algae, moss and lycophytes to dozens, and sometimes over 50 members in angiosperms. Phylogenetic analysis indicated that at least four subclades (Class I and three subclades of Class II) have been occurred in the ancestor of spermatophyte (seed plant). Both dispersed duplication and segmental duplication or whole-genome duplication (WGD) contributed significantly to the expansion of the TCP gene family over the course of evolution. Our findings provide a comprehensive evolutionary analysis of the TCP gene family and highlight the importance of gene duplications in the evolution of this plant-specific transcription factors. [ABSTRACT FROM AUTHOR]