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This article discusses the evolution and diversity of secondary cell walls (SCWs) in seed plants. The study used cryoSEM to analyze macrofibrils in 33 different angiosperm and gymnosperm species. The results showed that angiosperms generally have narrower macrofibrils compared to gymnosperms, but there are exceptions. The findings provide insights into wood nanostructure and cell wall composition, which can be useful for selecting or engineering desirable wood properties and improving carbon sequestration in plantation forests. The study also examines the evolution of macrofibril size in seed plants, specifically focusing on angiosperms and gymnosperms. The researchers found that large macrofibrils are characteristic of gymnosperms, while small macrofibrils are characteristic of angiosperms. However, they also discovered an intermediate macrofibril size in the Liriodendron genus. The researchers speculate that this may be due to differences in cell wall composition or environmental factors. Further research is needed to investigate these factors and their impact on carbon sequestration and storage by plants. [Extracted from the article]

The DOF (DNA-binding with one finger) transcription factors are exclusive to plants and play crucial roles in plant growth, development, and environmental adaptation. Although extensive research has been conducted on the Dof gene family in Arabidopsis, maize, and Solanum, investigations concerning the role of this gene family in Liriodendron remain unreported, leaving its biological function largely unknown. In this study, we performed a comprehensive genome-wide identification of the Dof gene family based on the Liriodendron genome, resulting in the discovery of a total of 17 LcDof gene members. Based on the results of phylogenetic analysis, the 17 LcDof proteins were classified into eight subfamilies. The motif analysis revealed the diverse nature of motifs within the D1 subfamily, which includes a distinct type of Dof transcription factor known as CDF (Cycling Dof Factor). We further characterized the chromosomal distribution, gene structure, conserved protein motifs, and cis-elements in the promoter regions. Additionally, utilizing transcriptome data from Liriodendron hybrids and conducting RT-qPCR experiments, we investigated the expression patterns of LhDofs under various abiotic stresses such as drought, cold, and heat stress. Notably, we found that several LhDofs, particularly LhDof4 and LhDof6, were significantly upregulated in response to abiotic stress. Furthermore, we cloned LhDof4 and LhDof6 genes and found that its encoding protein was mainly located in the nucleus by transient transformation in Liriodendron hybrids protoplast. Subsequently, we used LhDof6-overexpressing Liriodendron hybrid seedlings. We found that overexpression of LhDof6 enhanced the cold tolerance of the plants, increasing their survival rate at −20 °C. This result was further validated by changes in physiological indicators. [ABSTRACT FROM AUTHOR]

Seventeen Gram-negative, facultatively anaerobic bacterial strains were isolated from bleeding cankers of various broadleaf hosts and oak rhizosphere soil in Great Britain. The strains were tentatively identified as belonging to the genus Raoultella based on 16S rRNA gene sequencing. Multilocus sequence analysis (MLSA), based on four protein-encoding genes (fusA, leuS, pyrG, and rpoB), separated the strains into three clusters within the Raoultella genus clade. The majority of strains clustered with the type strain of Raoultella terrigena, with the remaining strains divided into two clusters with no known type strain. Whole genome sequencing comparisons confirmed these two clusters of strains as belonging to two novel Raoultella species which can be differentiated phenotypically from their current closest phylogenetic relatives. Therefore, two novel species are proposed: Raoultella scottia sp. nov. (type strain = BAC 10a-01-01T = LMG 33072T = CCUG 77096T) and Raoultella lignicola sp. nov. (type strain = TW_WC1a.1T = LMG 33073T = CCUG 77094T). [ABSTRACT FROM AUTHOR]

Seventeen Gram-negative, facultatively anaerobic bacterial strains were isolated from bleeding cankers of various broadleaf hosts and oak rhizosphere soil in Great Britain. The strains were tentatively identified as belonging to the genus Raoultella based on 16S rRNA gene sequencing. Multilocus sequence analysis (MLSA), based on four protein-encoding genes (fusA, leuS, pyrG, and rpoB), separated the strains into three clusters within the Raoultella genus clade. The majority of strains clustered with the type strain of Raoultella terrigena, with the remaining strains divided into two clusters with no known type strain. Whole genome sequencing comparisons confirmed these two clusters of strains as belonging to two novel Raoultella species which can be differentiated phenotypically from their current closest phylogenetic relatives. Therefore, two novel species are proposed: Raoultella scottia sp. nov. (type strain = BAC 10a-01-01T = LMG 33072T = CCUG 77096T) and Raoultella lignicola sp. nov. (type strain = TW_WC1a.1T = LMG 33073T = CCUG 77094T).

The DOF (DNA-binding with one finger) transcription factors are exclusive to plants and play crucial roles in plant growth, development, and environmental adaptation. Although extensive research has been conducted on the Dof gene family in Arabidopsis, maize, and Solanum, investigations concerning the role of this gene family in Liriodendron remain unreported, leaving its biological function largely unknown. In this study, we performed a comprehensive genome-wide identification of the Dof gene family based on the Liriodendron genome, resulting in the discovery of a total of 17 LcDof gene members. Based on the results of phylogenetic analysis, the 17 LcDof proteins were classified into eight subfamilies. The motif analysis revealed the diverse nature of motifs within the D1 subfamily, which includes a distinct type of Dof transcription factor known as CDF (Cycling Dof Factor). We further characterized the chromosomal distribution, gene structure, conserved protein motifs, and cis-elements in the promoter regions. Additionally, utilizing transcriptome data from Liriodendron hybrids and conducting RT-qPCR experiments, we investigated the expression patterns of LhDofs under various abiotic stresses such as drought, cold, and heat stress. Notably, we found that several LhDofs, particularly LhDof4 and LhDof6, were significantly upregulated in response to abiotic stress. Furthermore, we cloned LhDof4 and LhDof6 genes and found that its encoding protein was mainly located in the nucleus by transient transformation in Liriodendron hybrids protoplast. Subsequently, we used LhDof6-overexpressing Liriodendron hybrid seedlings. We found that overexpression of LhDof6 enhanced the cold tolerance of the plants, increasing their survival rate at −20 °C. This result was further validated by changes in physiological indicators.

Introduction: GRAS genes encode plant-specific transcription factors that play essential roles in plant growth and development. However, the members and the function of the GRAS gene family have not been reported in Liriodendron chinense. L. chinense, a tree species in the Magnolia family that produces excellent timber for daily life and industry. In addition, it is a good relict species for plant evolution research. Methods: Therefore, we conducted a genome-wide study of the LcGRAS gene family and identified 49 LcGRAS genes in L. chinense. Results: We found that LcGRAS could be divided into 13 sub-groups, among which there is a unique branch named HAM-t. We carried out RNA sequencing analysis of the somatic embryos from L. chinense and found that LcGRAS genes are mainly expressed after heart-stage embryo development, suggesting that LcGRAS may have a function during somatic embryogenesis. We also investigated whether GRAS genes are responsive to stress by carrying out RNA sequencing (RNA-seq) analysis, and we found that the genes in the PAT subfamily were activated upon stress treatment, suggesting that these genes may help plants survive stressful environments. We found that PIF was downregulated and COR was upregulated after the transient overexpression of PATs, suggesting that PAT may be upstream regulators of cold stress. Discussion: Collectively, LcGRAS genes are conserved and play essential roles in plant development and adaptation to abiotic stress. [ABSTRACT FROM AUTHOR]

The plant phosphatidylethanolamine-binding protein (PEBP) gene family plays important roles in regulating flowering time and vegetative growth. Compared with its parents, Liriodendron hybrids (Liriodendron chinense (Hemsl.) Sarg. × L. tulipifera L.), have obvious heterosis in terms of higher seed germination, fast growth, bright flower colors, and long growth seasons. However, the genome-wide identification and functional analysis of PEBP genes that contribute to the heterosis of Liriodendron hybrids have not been studied. In this study, we characterized four members of expressed LhPEBP genes in Liriodendron hybrids and divided them into three subfamilies based on their phylogenetic relationships: FT-like (LhFT), TFL1-like (LhTFL1), and MFT-like (LhMFT1 and LhMFT2). A functional analysis of Arabidopsis showed that the overexpression of LhFT significantly promoted flowering, and the LhTFL1 gene induced a wide dispersion of the flowering timing. LhMFTs function differently, with LhMFT2 suppressing flowering, while LhMFT1 accelerates it and had a stronger promoting effect on the early stage of seed germination. Additionally, the seed germination of the LhMFT lines was relatively less influenced by ABA, while the transgenic LhFT and LhTFL1 lines were sensitive to both ABA and GA3. These results provide valuable insights into the functions of LhPEBP genes in flowering and seed germination. [ABSTRACT FROM AUTHOR]

The auxin polar transporter, PIN-FORMED 2 (PIN2) plays an important role in root development. However, it remains unclear whether PIN2 genes form two Liriodendron species, L. chinense (LcPIN2) and L. tulipifera (LtPIN2), are both involved in root development and whether and to what extent these two genes diverge in function. Here, we cloned and overexpressed LcPIN2 and LtPIN2 in Arabidopsis thaliana wild-type (WT) and Atpin2 mutant. Phylogenetic and sequence analysis showed a small degree of differentiation between these two Liriodendron PIN2 genes. Tissue-specific gene expression analysis indicated that both Liriodendron PIN2 genes were highly expressed in roots, implying a potential role in root development. Finally, heterologous overexpression of LcPIN2 and LtPIN2 in Arabidopsis both significantly increased the root length compared to wild-type and empty vector. Furthermore, the root length defect in Atpin2 was complemented both by LcPIN2 and LtPIN2. However, heterologous overexpression of LcPIN2 and LtPIN2 cannot rescue the defect in root gravitropism of Atpin2 mutants. Taken together, our findings unravel PIN2 genes from the magnoliids plant Liriodendron were functionally conserved with AtPIN2 in the dicotyledonous plant Arabidopsis in regard to the regulation of root length, but not root gravitropism. This study also provides a potential target for genetic improvement of the root system in these valuable forest trees Liriodendron. [ABSTRACT FROM AUTHOR]

The relict woody plant genus Liriodendron contains two endangered species, Liriodendron chinense and Liriodendron tulipifera. Understanding the molecular mechanisms involved in early embryo development is important for horticultural and ecological research, particularly for the development of improved somatic embryogenesis systems. However, the specific molecular processes underlying embryogenesis in these species remain largely unexplored. To address this, we investigated expression of the WOX (WUSCHEL-related homeobox) gene family of transcription factors throughout somatic embryogenesis. We confirmed expression of eight out of 11 novel candidate LcWOX genes in L.chinense using qRT-PCR and examined spatiotemporal expression patterns of the expressed genes using stable reporter lines that had been transformed with different LcWOX promoters driving GUS expression. We observed embryo developmental stages and expression patterns that broadly correlated with those reported for Arabidopsis somatic embryogenesis. LcWUS was weakly expressed during the transition stage and was predominantly restricted to the apical meristem. LcWOX5 was specifically expressed in the root meristem and restricted to the cotyledons thereafter, and LcWOX4 expression was restricted to the vascular tissue of cotyledonary embryos. In contrast, LcWOX9 was expressed in the embryonic callus and the entire embryonic cell mass, then became restricted to the basal cells, indicating a potential role in regulating embryonic maintenance. Our findings provide insights into spatiotemporally specific WOX transcription and shed new light on potential functions of WOX genes during Liriodendron somatic embryogenesis.

The plant phosphatidylethanolamine-binding protein (PEBP) gene family plays important roles in regulating flowering time and vegetative growth. Compared with its parents, Liriodendron hybrids (Liriodendron chinense (Hemsl.) Sarg. × L. tulipifera L.), have obvious heterosis in terms of higher seed germination, fast growth, bright flower colors, and long growth seasons. However, the genome-wide identification and functional analysis of PEBP genes that contribute to the heterosis of Liriodendron hybrids have not been studied. In this study, we characterized four members of expressed LhPEBP genes in Liriodendron hybrids and divided them into three subfamilies based on their phylogenetic relationships: FT-like (LhFT), TFL1-like (LhTFL1), and MFT-like (LhMFT1 and LhMFT2). A functional analysis of Arabidopsis showed that the overexpression of LhFT significantly promoted flowering, and the LhTFL1 gene induced a wide dispersion of the flowering timing. LhMFTs function differently, with LhMFT2 suppressing flowering, while LhMFT1 accelerates it and had a stronger promoting effect on the early stage of seed germination. Additionally, the seed germination of the LhMFT lines was relatively less influenced by ABA, while the transgenic LhFT and LhTFL1 lines were sensitive to both ABA and GA3. These results provide valuable insights into the functions of LhPEBP genes in flowering and seed germination.

Predicting the impact of drought on forest ecosystem processes requires an understanding of trees' species-specific responses to drought, especially in the Eastern USA, where species composition is highly dynamic due to historical changes in land use and fire regime. Here, we adapted a framework that classifies trees' water-use strategy along the spectrum of isohydric to anisohydric behavior to determine the responses of three canopy-dominant species to drought. We used a collection of leaf-level gas exchange, tree-level sap flux and stand-level eddy covariance data collected in south-central Indiana from 2011 to 2013, which included an unusually severe drought in the summer of 2012. Our goal was to assess how patterns in the radial profile of sap flux and reliance on hydraulic capacitance differed among species of contrasting water-use strategies. In isohydric species, which included sugar maple (Acer saccharum Marsh.) and tulip poplar (Liriodendron tulipifera L.), we found that the sap flux in the outer xylem experienced dramatic declines during drought, but sap flux at inner xylem was buffered from reductions in water availability. In contrast, for anisohydric oak species (Quercus alba L. and Quercus rubra L.), we observed relatively smaller variations in sap flux during drought in both inner and outer xylem, and higher nighttime refilling when compared with isohydric species. This reliance on nocturnal refilling, which occurred coincident with a decoupling between leaf- and tree-level water-use dynamics, suggests that anisohydric species may benefit from a reliance on hydraulic capacitance to mitigate the risk of hydraulic failure associated with maintaining high transpiration rates during drought. In the case of both isohydric and anisohydric species, our work demonstrates that failure to account for shifts in the radial profile of sap flux during drought could introduce substantial bias in estimates of tree water use during both drought and non-drought periods.

Carotenoids are a group of naturally occurring tetraterpenoid with great industrial and pharmacological value. The carotenoids biosynthesis was extensively elucidated in model plants, such as tomato and monkey flower. However, little is known about the regulation mechanism of carotenoids biosynthesis. Here, we used L. chinense and L. tulipifera petals as materials to study the differences in carotenoid accumulation. We seek to unveil the mystery via morphologic, metabolomic, transcriptomic, bioinformatics and transgenic approaches. The paraffin section of petals showed that cell morphology was almost the same in Liriodendron genus , while the quantification of carotenoids content displayed a different pattern in petals between two Liriodendron species, with high concentrations of carotenoids accumulated on the orange band (OB) in L. tulipifera petals. Correspondingly, KEGG analysis showed that carotenoids biosynthesis pathway was significantly enriched in L. tulipifera. HPLC and transcriptome analyses indicated that LtLCYB might be a key gene functioning in OB coloration, thus further characterization was conducted. RT-qPCR and subcellular localization showed that LtLCYB was highly expressed in OB, and the LtLCYB was a chloroplast-located protein. Overexpression of LtLCYB in tobacco promoted the carotenoid synthesis. Furthermore, we identified R2R3-MYB TFs and found a potential member that maybe related to OB coloration. Y1H assay proved that LtMYB305 bind to LCYB promoter. Overexpression of LtMYB305 in tobacco increased the carotenoid content. Collectively, our findings proposed that the OB coloration in Liriodendron stems from the interspecies variation in the differential expression of CBP genes, and LtMYB305 takes a pivotal role in OB coloration. This study establishes a robust foundation for investigating the regulation mechanism of carotenoid synthesis, and offers valuable insights for the genetic improvement of petal colors in Liriodendron. • The flavonoids and chlorophyll biosynthesis were suppressed in the orange band of L. tulipifera. • Carotenoids biosynthesis pathway was specifically activated in the orange band of L. tulipifera petals. • LtLCYB were highly expressed in the middle part of L. tulipifera petals. • LtMYB305 regulated LtLCYB expression and increased the synthesis of carotenoids. [ABSTRACT FROM AUTHOR]

Climate change has a significant impact on species population size and distribution, global biodiversity, and ecological status. The Liriodendron genus contains two species: Liriodendron chinense and Liriodendron tulipifera, both playing important roles in timber, medicinal, and landscape purposes. However, little is known about their population distribution characteristics and important climatic factors shaping their suitability. In this research, we used the geological record data, 19 climate components, MaxEnt, and ArcGIS to recreate and analyze the potential population distribution and their alterations of Liriodendron within the world beneath the current and future scenarios of RCP 2.6, RCP 4.5, and RCP 8.5 in 2050 and 2070. Our results showed that: Liriodendron is suitable to grow in subtropical monsoon climate areas, and that the climatic factor of precipitation of warmest quarter exerts the greatest impact on L. chinense, with a contribution rate of 57.6%. Additionally, we showed that the climatic factor of precipitation of the driest month exerts the greatest impact on L. tulipifera, with a contribution rate of 60.5%. Further analysis exhibited that low temperature and temperature fluctuations are major temperature factors affecting L. chinense and L. tulipifera, respectively. Therefore, we predicted that by the 2050s and 2070s, the areas of Liriodendron suitable habitats would increase first and then decrease in three scenarios; except the area of L. tulipifera suitable habitats under RCP8.5, which shows a slight increase. We then conclude that the Liriodendron suitable areas would shift to high latitudes due to global climate warming. The information gained from this study will provide a reference for developing forest cultivation, management, and conservation strategies for these two important tree species, and also a basis for subsequent biogeographic research. [ABSTRACT FROM AUTHOR]

Ecological adaptive differentiation alters both the species diversity and intraspecific genetic diversity in forests, thus affecting the stability of forest ecosystems. Therefore, knowledge of the genetic underpinnings of the ecological adaptive differentiation of forest species is critical for effective species conservation. In this study, single‐nucleotide polymorphisms (SNPs) from population transcriptomes were used to investigate the spatial distribution of genetic variation in Liriodendron to assess whether environmental variables can explain genetic divergence. We examined the contributions of environmental variables to population divergence and explored the genetic underpinnings of local adaptation using a landscape genomic approach. Niche models and statistical analyses showed significant niche divergence between L. chinense and L. tulipifera, suggesting that ecological adaptation may play a crucial role in driving interspecific divergence. We detected a new fine‐scale genetic structure in L. chinense, and divergence of the six groups occurred during the late Pliocene to early Pleistocene. Redundancy analysis (RDA) revealed significant associations between genetic variation and multiple environmental variables. Environmental association analyses identified 67 environmental association loci (EALs; nonsynonymous SNPs) that underwent interspecific or intraspecific differentiation, 28 of which were associated with adaptive genes. These 28 candidate adaptive loci provide substantial evidence for local adaptation in Liriodendron. Our findings reveal ecological adaptive divergence pattern between Liriodendron species and provide novel insight into the role of heterogeneous environments in shaping genetic structure and driving local adaptation among populations, informing future L. chinense conservation efforts. [ABSTRACT FROM AUTHOR]

Abstract Background Nectar is a major floral attractant and reward for insects that ensures pollination. Liriodendron, a genus of the Magnoliaceae family, includes only two relict species, L. chinense and L. tulipifera, which are considered “basal angiosperms” according to plant evolutionary history. The flowers of Liriodendron plants are insect pollinated and secrete nectar to attract pollinators. To date, the morphology and anatomy of nectaries, the mechanism of nectar secretion and the molecular mechanism of nectary development in Liriodendron remain poorly understood. Methods In this study, we examined the nectary surface cells and change in starch in L. tulipifera by using scanning electron microscopy and periodic acid-Schiff techniques to select appropriate samples for subsequent research. Transcriptome sequencing was of the top and middle parts of immature nectaries and the middle part of mature and postsecretory nectaries in L. tulipifera was performed. We evaluated the expression profiles of 21 DEGs that are closely related to nectary development and nectar secretion for real-time quantitative PCR analysis. Results L. tulipifera nectaries are starch-storing nectaries and are located in the top and middle parts of L. tulipifera petals. After analyzing the RNA-seq data, we obtained 115.26 Gb of clean data in 12 libraries and mapped the results to the L. chinense reference genome with 71.02–79.77% efficiency. In total, 26,955 DEGs were identified by performing six pairwise comparisons. The flavonoid biosynthesis, phenylpropanoid biosynthesis, anthocyanin biosynthesis and starch and sucrose metabolism pathways were enriched and related to nectar secretion and pigment change. We identified 56 transcription factor families, and members of the TCP, Trihelix, C2H2, ERF, and MADS families changed dynamically during nectary development. Moreover, to further verify the accuracy of the RNA-seq results, we validated the expression profiles of 21 candidate genes. Conclusions We evaluated the nectary development and secretion processes comprehensively and identified many related candidate genes in L. tulipifera. These findings suggest that nectaries play important roles in flavonoid synthesis and petal color presentation.

• Comprehensive metabolites profiles among the petals of Liriodendron. • Different accumulation of chlorogenic acid was found in the petal of the Liriodendron. • The chlorogenic acid synthesis pathway was identified in Liriodendron petals. • CYP98A gene family showed significant expansion in Liriodendron. Petal secondary metabolites can affect pollinator selection and invasion of pathogenic microorganisms to change the adaptability to the environment. Meanwhile, the active components in petal are widely used in many aspects of human society. At present, research into bioactive compounds in Liriodendron have mainly focused on bark, leaf and root tissues, with few studies systematically studying the differences in secondary metabolite content of petals coming from different Liriodendron accessions. By combining untargeted LC–MS metabolome analysis with analysis of the Liriodendron petal transcriptome, the biosynthetic pathway of activity in Liriodendron petals was studied, and the 6097 different accumulated metabolites were identified in different Liriodendron. These differentially accumulated metabolites (DAMs) are synthesized through multiple secondary metabolic pathways, with a strong enrichment for flavonoid and phenylpropanoid biosynthetic compounds, suggesting that these active substances may be potentially valid medicinal components. In this study, the accumulation of chlorogenic acid (CGA) was increased in the petals of L. chinense. In addition, the chlorogenic acid synthesis pathway, which is mainly involved in the regulation of multiple CYP98A enzymes. These results reveal differential accumulation of secondary metabolites and potential medicinal ingredients in Liriodendron petals and thus provide a basis for further effective utilization of petals. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Background Liriodendron is a genus of Magnoliaceae, which consists of two relict species, Liriodendron chinense and L. tulipifera. Although the morphologies are highly similar, the two species exhibit different adaptive capacity. Dehydrins (DHNs) are abiotic stresses resistant proteins in planta, which are associated with adaptive evolution. To better understand the evolution divergence between L. chinense and L. tulipifera and how DHN genes are associated with adaptation evolution, we firstly investigated the DNA polymorphisms of the LcDHN-like gene in 21 L. chinense and 6 L. tulipifera populations. Results A 707 bp LcDHN-like gene was cloned, which included a 477 bp open reading frame (ORF) and coding 158 amino acids. 311 LcDHN-like gDNA sequences were obtained from 70 L. chinense and 35 L. tulipifera individuals. The AMOVA and phylogenetic relationship analysis showed significant differences between the two species. A higher genetic diversity was observed in L. tulipifera compared to L. chinense, in consistent with the higher adaptive capacity of L. tulipifera. Our data also suggested that the LcDHN-like genes’ polymorphisms were under neutral mutation and purifying selection model in the L. chinense and L. tulipifera populations, respectively. The distinct expanding range and rate between the two species, haplotypes shared only in L.chinense’s nearby populations, and wide dispersals in L. tulipifera could contribute to the obscure east-west separation in L. chinense and entirely unordered phylogeny in L. tulipifera. The completely separated nonsynonymous substitution at position 875 and the higher range scope of aliphatic index in L. tulipifera populations may be related with its higher adaptive capacity. Taken together, our study suggests LcDHN-like gene is a potential mark gene responsible for adaptive evolution divergence in Liriodendron. Conclusions Significant differences and completely distinct haplogroups between L. chinense and L. tulipifera showed that the two species have evolved into different directions. The more widely distribution, earlier haplogroups divergence events, and richer SNPs variations in L. tulipifera could imply its stronger adaptation in this species. And potential effect of the allelic variations in LcDHN-like gene may reflect the difference of water stress and chill tolerance between L. chinense and L. tulipifera, which could provide some information for further adaption evolution studies of Liriodendron.

Climate change has a significant impact on species population size and distribution, global biodiversity, and ecological status. The Liriodendron genus contains two species: Liriodendron chinense and Liriodendron tulipifera, both playing important roles in timber, medicinal, and landscape purposes. However, little is known about their population distribution characteristics and important climatic factors shaping their suitability. In this research, we used the geological record data, 19 climate components, MaxEnt, and ArcGIS to recreate and analyze the potential population distribution and their alterations of Liriodendron within the world beneath the current and future scenarios of RCP 2.6, RCP 4.5, and RCP 8.5 in 2050 and 2070. Our results showed that: Liriodendron is suitable to grow in subtropical monsoon climate areas, and that the climatic factor of precipitation of warmest quarter exerts the greatest impact on L. chinense, with a contribution rate of 57.6%. Additionally, we showed that the climatic factor of precipitation of the driest month exerts the greatest impact on L. tulipifera, with a contribution rate of 60.5%. Further analysis exhibited that low temperature and temperature fluctuations are major temperature factors affecting L. chinense and L. tulipifera, respectively. Therefore, we predicted that by the 2050s and 2070s, the areas of Liriodendron suitable habitats would increase first and then decrease in three scenarios; except the area of L. tulipifera suitable habitats under RCP8.5, which shows a slight increase. We then conclude that the Liriodendron suitable areas would shift to high latitudes due to global climate warming. The information gained from this study will provide a reference for developing forest cultivation, management, and conservation strategies for these two important tree species, and also a basis for subsequent biogeographic research.

Nitrogen forms can affect metal accumulation in plants and tolerance to metals, but a few published studies on the effects on Cu toxicity and Cu accumulation in plants are scarce. Thus, the objective of this study was to evaluate the responses of Liriodendron chinense to different nitrogen forms, by the oxidative stress, antioxidant enzymes system, GSH-AsA cycle, Cu uptake, translocation, and accumulation under Cu stress. We found that Cu-induced growth inhibiting was alleviated by added exclusive NO 3 - -N. Adding N as NH 4 + -N with or without NO 3 - -N was aggravated as evidenced by significantly elevated malonaldehyde (MDA) and hydrogen peroxide (H 2 O 2 ) compared to N-Null. Cu exposure and adding NH 4 + -N inhibited superoxide dismutase activity, but remarkably stimulated the activities of catalase and peroxidase, the efficiency of glutathione-ascorbate (GSH-AsA) cycle, and the activity of glutathione reductase and nitrate reductase, with respect to the control. However, adding exclusive NO 3 - -N progressively restored the alteration of antioxidant to prevent Cu-induced oxidative stress. Additionally, adding exclusive NO 3 - -N significantly promoted the Cu uptake and accumulation in roots, but reduced Cu concentration in leaves, accompanied by the inhibited Cu translocation factor from roots to shoots by 36.7%, when compared with N-Null. Overall, adding NO 3 - -N alleviated its Cu toxicity by preventing Cu-induced oxidative stress and inhibiting Cu translocation from roots to shoots, which provides an effective strategy for phytostabilization in Cu-contaminated lands., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The MYB transcription factor family is one of the largest families in plants, and its members have various biological functions. R2R3-MYB genes are involved in the synthesis of pigments that yield petal colors. Liriodendron plants are widely cultivated as ornamental trees owing to their peculiar leaves, tulip-like flowers, and colorful petals. However, the mechanism underlying petal coloring in this species is unknown, and minimal information about MYB genes in Liriodendron is available. Herein, this study aimed to discern gene(s) involved in petal coloration in Liriodendron via genome-wide identification, HPLC, and RT-qPCR assays. In total, 204 LcMYB superfamily genes were identified in the Liriodendron chinense genome, and 85 R2R3-MYB genes were mapped onto 19 chromosomes. Chromosome 4 contained the most (10) R2R3-MYB genes, and chromosomes 14 and 16 contained the fewest (only one). MEME analysis showed that R2R3-MYB proteins in L. chinense were highly conserved and that their exon-intron structures varied. The HPLC results showed that three major carotenoids were uniformly distributed in the petals of L. chinense, while lycopene and β-carotene were concentrated in the orange band region in the petals of Liriodendron tulipifera. Furthermore, the expression profiles via RT-qPCR assays revealed that four R2R3-MYB genes were expressed at the highest levels at the S3P/S4P stage in L. tulipifera. This result combined with the HPLC results showed that these four R2R3-MYB genes might participate in carotenoid synthesis in the petals of L. tulipifera. This work laid a cornerstone for further functional characterization of R2R3-MYB genes in Liriodendron plants.

Colletotrichum gloeosporioides is a hemibiotrophic pathogen causing significant losses to economically important crops and forest trees, including Liriodendron. To explore the interaction between C. gloeosporioides and Liriodendron and to identify the candidate genes determining the pathogenesis, we sequenced and assembled the whole genome of C. gloeosporioides Lc1 (CgLc1) using PacBio and Illumina next generation sequencing and performed a comparative genomic analysis between CgLc1 and Cg01, the latter being a described endophytic species of the C. gloeosporioides complex. Gene structure prediction identified 15,744 protein-coding genes and 837 noncoding RNAs. Species-specific genes were characterized using an ortholog analysis followed by a pathway enrichment analysis, which showed that genes specific to CgLc1 were enriched for the arginine biosynthetic process. Furthermore, genome synteny analysis revealed that most of the protein-coding genes fell into collinear blocks. However, two clusters of polyketide synthase genes were identified to be specific for CgLc1, suggesting that they might have an important role in virulence control. Transcriptional regulators coexpressed with polyketide synthase genes were detected through a Weighted Correlation Network Analysis. Taken together, this work provides new insight into the virulence- and pathogenesis-associated genes present in C. gloeosporioides and its possible lifestyle. [ABSTRACT FROM AUTHOR]

In order to evaluate the feasibility that the three raw materials of lake sediment, clay, liriodendron were mixed for producing ceramsite and examine their sintering characteristics, the specific surface area, pore size distribution, bulk and apparent density were chosen as the study object. The results showed that at the lower preheating and sintering temperatures and duration, many small pores were formed in the inner of the ceramsites, while at the higher preheating and sintering temperatures and duration, small pores started melting to form larger pores resulting in the decline of the specific surface area and the increase of the bulk and apparent density. As the lake sediments decreased, the specific surface area of the ceramsites also declined and the bulk and apparent density increased, while as the amount of the liriodendron rose, the specific surface area would also increase and the bulk and apparent density decrease. In addition, the influence for the increase of the organic matters was greater than the influence for the decline of the preheating and sintering temperatures and duration. [ABSTRACT FROM AUTHOR]

Premise of research. Glacial cycles during the last circa 5 Myr altered the distribution of genetic variance observed today. During periods of unfavorable climate, populations survive glacial maxima in refugial microclimates where growth and reproduction are possible. Peninsulas provide refuge but may alter demographic processes in comparison with mainland populations. The Florida peninsula is an important refugium for plant populations, and its unique geologic history created environments that differ from those of nearby mainland sites. Peninsular demographic effects and adaptation may contribute to genetic diversity. We investigate the genetic divergence of tulip trees (Liriodendron tulipifera L.) across much of their range and interpret our results in the context of eastern North American phylogeography, detectable signals of population expansion during recolonization, and peninsular demographic effects. We also test the hypothesis that peninsular populations represent a new species or subspecies within L. tulipifera. Methodology. Population structure was evaluated in a sample of 141 individuals from 56 populations at one nuclear DNA region (LFY) and three cpDNA intergenic regions (psbA-trnH , trnL intron-trnF , trnK 5′- matK). We use population genetic methods to identify clusters, test their significance, and estimate coalescent parameters. Phylogenetic trees and population trees were built to observe relationships between groups. Pivotal results. Genetic clusters determined with population genetic and phylogenetic methods are regionally coherent. We observe a secondary contact zone in the Gulf Coast near the Apalachicola River basin. Florida peninsula populations both are genetically diverse and experience low migration from mainland populations. Conclusions. We detect patterns of phylogeographic clustering using population genetic and phylogenetic methods. Analysis of genetic diversity and gene flow indicates range expansion has influenced their patterns. A demographic peninsular effect appears to have altered patterns of genetic diversity, linkage disequilibrium, and gene flow between peninsular and mainland populations. We interpret these results to indicate that a subspecies of L. tulipifera from the Florida peninsula exists. [ABSTRACT FROM AUTHOR]

The composition and dominance of 1256 witness (land survey) trees were compiled for the early Colonial era (pre-1700) in two locations in eastern Virginia, a region where studies of such information are lacking. The study locations are the Marine Corps Base Quantico and the Cheatham Annex Naval Supply Center, both along major rivers of Tidewater Virginia. At Quantico, a total of 754 witness trees comprising 22 species were recorded. Oak (Quercus) species made up 67% of these trees, followed by hickory (Carya; 15%), poplar (Liriodendron), gum (Nyssa), and pine (Pinus) each representing 4% of the forest composition. At Cheatham Annex a total of 502 witness trees from 24 species were recorded. Oaks made up 57% of the total composition followed by hickory (13%), pine (10%), poplar (5%), and gum (5%). There was a dearth of late successional, fire sensitive species at both locations, despite the presence of many mesic locations that should support such species. This suggests Native American activity (e.g., burning and land clearing) was an important factor affecting forests in eastern Virginia. This research provides a better understanding of the original forests of eastern Virginia and can serve as a baseline for making comparisons with present day forests to assess forest change since the Colonial era. [ABSTRACT FROM AUTHOR]

Background: Liriodendron is a genus of Magnoliaceae, which consists of two relict species, Liriodendron chinense and L. tulipifera. Although the morphologies are highly similar, the two species exhibit different adaptive capacity. Dehydrins (DHNs) are abiotic stresses resistant proteins in planta, which are associated with adaptive evolution. To better understand the evolution divergence between L. chinense and L. tulipifera and how DHN genes are associated with adaptation evolution, we firstly investigated the DNA polymorphisms of the LcDHN-like gene in 21 L. chinense and 6 L. tulipifera populations. Results: A 707 bp LcDHN-like gene was cloned, which included a 477 bp open reading frame (ORF) and coding 158 amino acids. 311 LcDHN-like gDNA sequences were obtained from 70 L. chinense and 35 L. tulipifera individuals. The AMOVA and phylogenetic relationship analysis showed significant differences between the two species. A higher genetic diversity was observed in L. tulipifera compared to L. chinense, in consistent with the higher adaptive capacity of L. tulipifera. Our data also suggested that the LcDHN-like genes' polymorphisms were under neutral mutation and purifying selection model in the L. chinense and L. tulipifera populations, respectively. The distinct expanding range and rate between the two species, haplotypes shared only in L.chinense's nearby populations, and wide dispersals in L. tulipifera could contribute to the obscure east-west separation in L. chinense and entirely unordered phylogeny in L. tulipifera. The completely separated nonsynonymous substitution at position 875 and the higher range scope of aliphatic index in L. tulipifera populations may be related with its higher adaptive capacity. Taken together, our study suggests LcDHN-like gene is a potential mark gene responsible for adaptive evolution divergence in Liriodendron. Conclusions: Significant differences and completely distinct haplogroups between L. chinense and L. tulipifera showed that the two species have evolved into different directions. The more widely distribution, earlier haplogroups divergence events, and richer SNPs variations in L. tulipifera could imply its stronger adaptation in this species. And potential effect of the allelic variations in LcDHN-like gene may reflect the difference of water stress and chill tolerance between L. chinense and L. tulipifera, which could provide some information for further adaption evolution studies of Liriodendron. [ABSTRACT FROM AUTHOR]

Liriodendron tulifipera L. belongs to Magnoliaceae which is one of the basal angiosperm families. To understand intra-species variations on chloroplast genome in Liriodendron genus, we presented complete chloroplast genome of L. tulifipera, which is 156,387 bp long and has four subregions: 85,606 bp of large single copy (LSC) and 18,778 bp of small single copy (SSC) regions are separated by 26,002 bp of inverted repeat (IR) regions including 129 genes (84 coding genes, 8 rRNAs, and 37 tRNAs). The overall GC content of the chloroplast genome is 37.0% and those in the LSC, SSC, and IR regions are 34.9%, 30.5%, and 42.8%, respectively. Twelve single nucleotide polymorphisms (SNPs) located in one region and one insertion and deletion are found between two L. tulifipera genomes. INDEL Phylogenetic trees show that two L. tulifipera chloroplasts are clustered together and are sister to Magnolia species.

Liriodendron tulipifera L. is easily recognized by its heart-shaped of leaves and can grow up to 60 meters in North America. In this study, we presented second complete mitochondrial genome of L. tulipifera to understand intra-species variations. Its length is 156,387 bp and contains 66 genes (42 protein-coding genes, three rRNAs, and 21 tRNAs). The overall GC content of the mitochondrial genome is 43.5%, 365 single nucleotide polymorphisms (SNPs; 0.07%), and 2117 insertions and deletions (INDELs; 0.38%) are identified. Most of INDELs are from 1980 bp deletions on this mitochondrial genome. Phylogenetic trees show that intra-species relation in both Liriodendron and Arabidopsis shows are clustered tightly in each clade. In addition, monocots and eudicots are positioned in different manner from classical plant taxonomy, requiring more researches.

Introduction: GRAS genes encode plant-specific transcription factors that play essential roles in plant growth and development. However, the members and the function of the GRAS gene family have not been reported in Liriodendron chinense . L. chinense , a tree species in the Magnolia family that produces excellent timber for daily life and industry. In addition, it is a good relict species for plant evolution research., Methods: Therefore, we conducted a genome-wide study of the LcGRAS gene family and identified 49 LcGRAS genes in L. chinense ., Results: We found that LcGRAS could be divided into 13 sub-groups, among which there is a unique branch named HAM-t. We carried out RNA sequencing analysis of the somatic embryos from L. chinense and found that LcGRAS genes are mainly expressed after heart-stage embryo development, suggesting that LcGRAS may have a function during somatic embryogenesis. We also investigated whether GRAS genes are responsive to stress by carrying out RNA sequencing (RNA-seq) analysis, and we found that the genes in the PAT subfamily were activated upon stress treatment, suggesting that these genes may help plants survive stressful environments. We found that PIF was downregulated and COR was upregulated after the transient overexpression of PATs, suggesting that PAT may be upstream regulators of cold stress., Discussion: Collectively, LcGRAS genes are conserved and play essential roles in plant development and adaptation to abiotic stress., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Weng, Chen, Hao, Lu, Wu, Zhang, Wu, Shi and Chen.)

As one of the largest plant specific transcription factor families, NAC family members play an important role in plant growth, development and stress resistance. To investigate the function of NAC transcription factors during abiotic stress, as well as during somatic embryogenesis, we identified and characterized the NAC gene family in Liriodendron chinense. We found that most LcNAC members contain more than three exons, with a relatively conserved gene and motif structure, especially at the N-terminus. Interspecies collinearity analysis revealed a closer relationship between the L. chinense NACs and the P. trichocarpa NACs. We analyzed the expression of LcNAC in different tissues and under three abiotic stresses. We found that 12 genes were highly expressed during the ES3 and ES4 stages of somatic embryos, suggesting that they are involved in the development of somatic embryos. 6 LcNAC genes are highly expressed in flower organs. The expression pattern analysis of LcNACs based on transcriptome data and RT-qPCR obtained from L. chinense leaves indicated differential expression responses to drought, cold, and heat stress. Genes in the NAM subfamily expressed differently during abiotic stress, and LcNAC6/18/41/65 might be the key genes in response to abiotic stress. LcNAC6/18/41/65 were cloned and transiently transformed into Liriodendron protoplasts, where LcNAC18/65 was localized in cytoplasm and nucleus, and LcNAC6/41 was localized only in nucleus. Overall, our findings suggest a role of the NAC gene family during environmental stresses in L. chinense. This research provides a basis for further study of NAC genes in Liriodendron chinense., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Liriodendron is a Tertiary period relic tree genus with a typical East Asian and North American disjunction distribution pattern. As an angiosperm base group of trees, Liriodendron provides a valuable resource for the study of evolution processes. Here, we reconstruct the phylogeny and population genetic structure of Liriodendron based on the restriction site-associated DNA sequencing (RAD-Seq) of a wide collection of individuals from 16 populations. Our results reveal a clear phylogenetic break between L. chinense and L. tulipifera and obvious genetic divergence between the eastern and western populations of L. chinense, which are consistent with the patterns of geographical distributions. The phylogeographic history and long-term geographical isolation of the genus may be responsible for this pattern. Furthermore, a closer relationship was found between L. tulipifera and the eastern populations of L. chinense, indicating the ancient phylogeny of L. chinense in this area. The results of this study will aid in the development of scientific strategies for the conservation and utilization of the Liriodendron germplasm.

Street trees planted at tree pits with impermeable pavements are exposed to a high level of both, atmospheric and edaphic stress. For many species tree physiology, optimal growth, and consequently long-term vitality may be hampered under these harsh conditions. Therefore, maintaining the vitality and promoting the ecosystem services provided by urban trees, for example aesthetic values and microclimatic benefits, it is important to establish trees with a high tolerance to stressful urban environments. Measurements of leaf gas exchange, leaf water potential, leaf surface temperature and chlorophyll-fluorescence were used for identification of specific response of Corylus corluna L., Ginkgo biloba L., Liriodendron tulipifera L., and Tilia cordata Mill. 'Greenspire'. The summer months in 2013 with a period of heat and drought over eight weeks only interrupted by two rainy days were appropriate to access tree's strategies to cope with low water availability. During the measurement period, the influence of high temperatures, high values of vapor pressure deficit (VPD) and low soil water availability on stomatal conductance, water-use efficiency (WUE) and leaf water potential (Ψmin, Ψmax ) was highest for Liriodendron followed by Ginkgo. These species showed high reductions in WUE in case of higher air temperatures and high values of VPD. Results indicate an avoidance strategy under increasing heat and VPD. In contrast, Corylus and Tilia followed a tolerance strategy indicated by decreasing values of Ψmin and lower reductions of WUE. In conclusion, wide species-specific variation in response to high temperatures and high VPD indicates that substantial potential exists in the selection for dry and hot urban places. [ABSTRACT FROM AUTHOR]