Family Magnoliaceae Research Articles

Systematic Characterization of GATA Transcription Factors in Liriodendron chinense and Functional Validation in Abiotic Stresses.

The Liriodendron chinense in the Magnoliaceae family is an endangered tree species useful for its socio-economic and ecological benefits. Abiotic stresses (cold, heat, and drought stress), among other factors, affect its growth, development, and distribution. However, GATA transcription factors (TFs) respond to various abiotic stresses and play a significant role in plant acclimatization to abiotic stresses. To determine the function of GATA TFs in L. chinense, we investigated the GATA genes in the genome of L. chinense. In this study, a total of 18 GATA genes were identified, which were randomly distributed on 12 of the total 17 chromosomes. These GATA genes clustered together in four separate groups based on their phylogenetic relationships, gene structures, and domain conservation arrangements. Detailed interspecies phylogenetic analyses of the GATA gene family demonstrated a conservation of the GATAs and a probable diversification that prompted gene diversification in plant species. In addition, the LcGATA gene family was shown to be evolutionarily closer to that of O. sativa, giving an insight into the possible LcGATA gene functions. Investigations of LcGATA gene duplication showed four gene duplicate pairs by the segmental duplication event, and these genes were a result of strong purified selection. Analysis of the cis-regulatory elements demonstrated a significant representation of the abiotic stress elements in the promoter regions of the LcGATA genes. Additional gene expressions through transcriptome and qPCR analyses revealed a significant upregulation of LcGATA17, and LcGATA18 in various stresses, including heat, cold, and drought stress in all time points analyzed. We concluded that the LcGATA genes play a pivotal role in regulating abiotic stress in L. chinense. In summary, our results provide new insights into understanding of the LcGATA gene family and their regulatory functions during abiotic stresses.

Comparitive Analysis of the Chloroplast Genomes of Three Houpoea Plants.

The genus Houpoea belongs to the family Magnoliaceae, and the species in this genus have important medicinal values. However, the investigation of the correlation between the evolution of the genus and its phylogeny has been severely hampered by the unknown range of species within the genus and the paucity of research on its chloroplast genome. Thus, we selected three species of Houpoea: Houpoea officinalis var officinalis (OO), Houpoea officinalis var. biloba (OB), and Houpoea rostrata (R). With lengths of 160,153 bp (OO), 160,011 bp (OB), and 160,070 bp (R), respectively, the whole chloroplast genomes (CPGs) of these three Houpoea plants were acquired via Illumina sequencing technology, and the findings were annotated and evaluated. These three chloroplast genomes were revealed by the annotation findings to be typical tetrads. A total of 131, 132, and 120 different genes were annotated. The CPGs of the three species had 52, 47, and 56 repeat sequences, which were primarily found in the ycf2 gene. A useful tool for identifying species is the approximately 170 simple sequence repeats (SSRs) that have been found. The border area of the reverse repetition region (IR) was studied, and it was shown that across the three Houpoea plants, it is highly conservative, with only changes between H. rostrata and the other two plants observed. Numerous highly variable areas (rps3-rps19, rpl32-trnL, ycf1, ccsA, etc.) have the potential to serve as the barcode label for Houpoea, according to an examination of mVISTA and nucleotide diversity (Pi). Phylogenetic relation indicates that Houpoea is a monophyletic taxon, and its genus range and systematic position are consistent with the Magnoliaceae system of Sima Yongkang-Lu Shugang, including five species and varieties of H. officinalis var. officinalis, H. rostrata, H. officinalis var. biloba, Houpoea obovate, and Houpoea tripetala, which evolved and differentiated from the ancestors of Houpoea to the present Houpoea in the above order. This study provides valuable information on the genus Houpoea, enriches the CPG information on Houpoea genus, and provides genetic resources for the further classification of and phylogenetic research on Houpoea.

Genome-Wide Identification and Abiotic-Stress-Responsive Expression of CKX Gene Family in Liriodendron chinense.

Liriodendron chinense is a tree species of the Magnoliaceae family, an ancient relict plant mainly used for landscaping and timber production due to its excellent material properties and ornamental value. The cytokinin oxidase/dehydrogenase (CKX) enzyme regulates cytokinin levels and plays an important role in plant growth, development, and resistance. However, too-high or too-low temperatures or soil drought can limit the growth of L. chinense, representing a key issue for research. Here, we identified the CKX gene family in the L. chinense genome and examined its transcriptional responses to cold, drought, and heat stresses. A total of five LcCKX genes, distributed on four chromosomes and divided into three phylogenetic groups, were identified across the whole L. chinense genome. Further analysis showed that multiple hormone- and stress-responsive cis-acting elements are located in the promoter regions of LcCKXs, indicating a potential role of these LcCKXs in plant growth, development, and response to environmental stresses. Based on existing transcriptome data, LcCKXs, especially LcCKX5, were found to transcriptionally respond to cold, heat, and drought stresses. Furthermore, quantitative reverse-transcription PCR (qRT-PCR) showed that LcCKX5 responds to drought stress in an ABA-dependent manner in stems and leaves and in an ABA-independent manner in roots. These results lay a foundation for functional research on LcCKX genes in the resistance breeding of the rare and endangered tree species of L. chinense.

STAY-GREEN Accelerates Chlorophyll Degradation in Magnolia sinostellata under the Condition of Light Deficiency.

Species of the Magnoliaceae family are valued for their ornamental qualities and are widely used in landscaping worldwide. However, many of these species are endangered in their natural environments, often due to being overshadowed by overstory canopies. The molecular mechanisms of Magnolia's sensitivity to shade have remained hitherto obscure. Our study sheds light on this conundrum by identifying critical genes involved in governing the plant's response to a light deficiency (LD) environment. In response to LD stress, Magnolia sinostellata leaves were endowed with a drastic dwindling in chlorophyll content, which was concomitant to the downregulation of the chlorophyll biosynthesis pathway and upregulation in the chlorophyll degradation pathway. The STAY-GREEN (MsSGR) gene was one of the most up-regulated genes, which was specifically localized in chloroplasts, and its overexpression in Arabidopsis and tobacco accelerated chlorophyll degradation. Sequence analysis of the MsSGR promoter revealed that it contains multiple phytohormone-responsive and light-responsive cis-acting elements and was activated by LD stress. A yeast two-hybrid analysis resulted in the identification of 24 proteins that putatively interact with MsSGR, among which eight were chloroplast-localized proteins that were significantly responsive to LD. Our findings demonstrate that light deficiency increases the expression of MsSGR, which in turn regulates chlorophyll degradation and interacts with multiple proteins to form a molecular cascade. Overall, our work has uncovered the mechanism by which MsSGR mediates chlorophyll degradation under LD stress conditions, providing insight into the molecular interactions network of MsSGR and contributing to a theoretical framework for understanding the endangerment of wild Magnoliaceae species.

Genome-Wide Identification and Expression Analysis of TPS Gene Family in Liriodendron chinense.

Terpenoids play a key role in plant growth and development, supporting resistance regulation and terpene synthase (TPS), which is the last link in the synthesis process of terpenoids. Liriodendron chinense, commonly called the Chinese tulip tree, is a rare and endangered tree species of the family Magnoliaceae. However, the genome-wide identification of the TPS gene family and its transcriptional responses to development and abiotic stress are still unclear. In the present study, we identified a total of 58 TPS genes throughout the L. chinense genome. A phylogenetic tree analysis showed that they were clustered into five subfamilies and unevenly distributed across six chromosomes. A cis-acting element analysis indicated that LcTPSs were assumed to be highly responsive to stress hormones, such as methyl jasmonate (MeJA) and abscisic acid (ABA). Consistent with this, transcriptome data showed that most LcTPS genes responded to abiotic stress, such as cold, drought, and hot stress, at the transcriptional level. Further analysis showed that LcTPS genes were expressed in a tissue-dependent manner, especially in buds, leaves, and bark. Quantitative reverse transcription PCR (qRT-PCR) analysis confirmed that LcTPS expression was significantly higher in mature leaves compared to young leaves. These results provide a reference for understanding the function and role of the TPS family, laying a foundation for further study of the regulation of TPS in terpenoid biosynthesis in L. chinense.

Computational approaches to define poncirin from Magnolia champaka leaves as a novel multi-target inhibitor of SARS-CoV-2

Phytochemical-based drug discovery against the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has been the focus of the current scenario. In this context, we aimed to perform the phytochemical profiling of Magnolia champaka, an evergreen tree from the Magnoliaceae family, in order to perform a virtual screening of its phytoconstituents against different biological targets of SARS-CoV-2. The phytochemicals identified from the ethanol extract of M. champaka leaves using liquid chromatography-mass spectroscopy (LC-MS) technique were screened against SARS-CoV-2 spike glycoprotein (PDB ID: 6M0J), main protease/Mpro (PDB ID: 6LU7), and papain-like protease/PLpro (PDB ID: 7CMD) through computational tools. The experimentation design included molecular docking simulation, molecular dynamics simulation, and binding free energy calculations. Through molecular docking simulation, we identified poncirin as a common potential inhibitor of all the above-mentioned target proteins. In addition, molecular dynamics simulations, binding free energy calculations, and PCA analysis also supported the outcomes of the virtual screening. By the virtue of all the in silico results obtained, poncirin could be taken for in vitro and in vivo studies in near future. Communicated by Ramaswamy H. Sarma

Volatile Profiling of Magnolia champaca Accessions by Gas Chromatography Mass Spectrometry Coupled with Chemometrics.

Magnolia champaca (L.) Baill. ex Pierre of family Magnoliaceae, is a perennial tree with aromatic, ethnobotanical, and medicinal uses. The M. champaca leaf is reported to have a myriad of therapeutic activities, however, there are limited reports available on the chemical composition of the leaf essential oil of M. champaca. The present study explored the variation in the yield and chemical composition of leaf essential oil isolated from 52 accessions of M. champaca. Through hydrodistillation, essential oil yield was obtained, varied in the range of 0.06 ± 0.003% and 0.31 ± 0.015% (v/w) on a fresh weight basis. GC-MS analysis identified a total of 65 phytoconstituents accounting for 90.23 to 98.90% of the total oil. Sesquiterpene hydrocarbons (52.83 to 65.63%) constituted the major fraction followed by sesquiterpene alcohols (14.71 to 22.45%). The essential oils were found to be rich in β-elemene (6.64 to 38.80%), γ-muurolene (4.63 to 22.50%), and β-caryophyllene (1.10 to 20.74%). Chemometrics analyses such as PCA, PLS-DA, sPLS-DA, and cluster analyses such as hierarchical clustering, i.e., dendrogram and partitional clustering, i.e., K-means classified the essential oils of M. champaca populations into three different chemotypes: chemotype I (β-elemene), chemotype II (γ-muurolene) and chemotype III (β-caryophyllene). The chemical polymorphism analyzed in the studied populations would facilitate the selection of chemotypes with specific compounds. The chemotypes identified in the M. champaca populations could be developed as promising bio-resources for conservation and pharmaceutical application and further improvement of the taxa.

Genome-wide identification of XTH genes in Liriodendron chinense and functional characterization of LcXTH21.

Liriodendron chinense is a relic tree species of the family Magnoliaceae with multiple uses in timber production, landscape decoration, and afforestation. L. chinense often experiences drought stress in arid areas. However, the molecular basis underlying the drought response of L. chinense remains unclear. Many studies have reported that the xyloglucan endotransglucosylase/hydrolase (XTH) family plays an important role in drought stress resistance. Hereby, to explore the drought resistance mechanism of L. chinense, we identify XTH genes on a genome-wide scale in L. chinense. A total of 27 XTH genes were identified in L. chinense, and these genes were classified into three subfamilies. Drought treatment and RT-qPCR analysis revealed that six LcXTH genes significantly responded to drought stress, especially LcXTH21. Hence, we cloned the LcXTH21 gene and overexpressed it in tobacco via gene transfer to analyze its function. The roots of transgenic plants were more developed than those of wild-type plants under different polyethylene glycol (PEG) concentration, and further RT-qPCR analysis showed that LcXTH21 highly expressed in root compared to aboveground organs, indicating that LcXTH21 may play a role in drought resistance through promoting root development. The results of this study provide new insights into the roles of LcXTH genes in the drought stress response. Our findings will also aid future studies of the molecular mechanisms by which LcXTH genes contribute to the drought response.

First Report of Leaf Spot Caused by Colletotrichum fructicola on Magnolia wufengensis in Hubei, China.

Magnolia wufengensis belongs to the Magnoliaceae family. Its variation-rich flowers (tepal number from 9 to 46, tepal color from pink to bright red) and excellent wood characteristics (strong, straight, texture) have important ornamental and economic value (Duan et al. 2019; Luyi et al. 2006). M. wufengensis is popularly cultivated in parks, courtyards, mountains, and along roadsides. In May 2020, leaf spot symptoms were observed on over 85% of M. wufengensis in Yuyangguan Township, Wufeng County, Hubei Province (110.60°E, 30.21°N). The damaged area was over 18.7 hectares. Early symptoms began as small brown spots with a light-yellow halo. Gradual lesions expanded, and the center was withered, gray, and necrotic with a dark brown border. Eventually, several spots combined with larger irregular lesions, turning the leaves yellow and causing them to fall off. The border of lesions and healthy tissues were cut into small pieces (5×5 mm), and surface sterilized with 1% sodium hypochlorite solution for three minutes, rinsed three times with sterile water, and plated on potato dextrose agar (PDA) medium at 25±2 °C with a 12h photoperiod under fluorescent lighting. Pure isolates (MCS1228.1, MCS1228.4, MCS1228.9) were gray to pale grayish, and their average growth rate was 10.5±1.23 mm/day. Conidiophores were hyaline, aseptate, branched. Conidia were hyaline, aseptate, cylindrical, and 14.00 to 25.17 × 4.74 to 6.56 μm in size (average 17.48 × 5.58 μm) (n=50). Appressoria were brown and showed multivariate shape. The morphological characteristics of the isolates corresponded to the description given for Colletotrichum fructicola (Liu et al. 2015). Molecular identification was accomplished through amplification of the internal transcribed spacer (IST), actin (ACT), calmodulin (CAL), chitin synthase (CHS-1) glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and beta-tubulin (TUB2) genes (Fu et al. 2018). The ITS (OL800580.1, OL800581.1, OL800582.1), ACT (GenBank accession No. OL873155- OL873157), CAL (GenBank accession No. OL873158- OL873160), CHS-1 (GenBank accession No. OL873161- OL873163), GAPDH (GenBank accession No. OL873164- OL873166) and TUB2 (GenBank accession No. OL873167- OL873169) sequences were deposited in GenBank. A Bayesian inference phylogenetic tree based on multilocus sequences was constructed, and the sequences of the 3 isolations showed the same homology with C. fructicola (Fu et al. 2018). To fulfill Koch's postulates, 30 potted seedlings were inoculated with 1×10^6 conidia/ml suspension of each isolate by spraying the leaves, and 30 potted seedlings were sprayed with sterile distilled water as control. Inoculated and control plants were kept in a greenhouse with 25/15°C (day/night) temperature and 80% relative humidity. In addition, 30 healthy detached leaves free of pests and diseases were washed three times with sterile distilled water, air-dried, and artificially inoculated using a 6 mm (diameter) PDA medium (5 days incubation) with mycelium. 30 leaves were inoculated with sterile PDA medium as control. All leaves were sprayed with sterile water every 24 hours, covered with plastic wrap, and incubated at 25±2 °C, 100% humidity. The experiment was repeated three times. Similar symptoms to those found initially were both observed on all the inoculated potted seedlings and detached leaves after 14 days and 5 days post inoculation (dpi), respectively. Whereas the controls remained symptomless. The reisolated pathogens from symptomatic tissues were identical to the original isolates. In this study, isolated fungi associated with M. wufengensis leaf spot were identified as C. fructicola based on morphological and multiloci phylogenetic analyses, and Koch's postulates. Colletotrichum species are important plant pathogens and cause diseases in a wide variety of woody and herbaceous plants (Cannon et al. 2012). C. fructicola has been identified as a responsible pathogen for apple (Casanova et al. 2016), Fatsia japonica (Shi et al. 2017), and Rubus corchorifolius (Wu et al. 2021) leaf spot. To our knowledge, this is the first report of C. fructicola causing leaf spot in M. wufengensis in China. This research may contribute to the development of management strategies for this disease.

Antifungal Potential of Some Herb Decoctions and Essential Oils on Candida Species.

(1) Background: Candidiasis is a fungal infectious disease caused by opportunistic Candida species. The incidence of candidiasis has improved, due to prolonged antibiotic therapy and an increased number of immunocompromised patients. The purpose of this study was to evaluate if decoctions and essential oil (EO) of neem (Azadirachta indica, Meliaceae family), coptidis (Coptis chinensis, Ranunculaceae family), magnolia (Magnolia officinalis, Magnoliaceae family), scutellaria (Scutellaria barbata, Lamiaceae family), and the EO of manuka (Leptospermum scoparium, Myrtaceae family), have antifungal activity in vitro against some clinically prevalent species of Candida. (2) Methods: The antifungal activity was studied by the determination of the minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) against five Candida strains. The effect in dimorphic transition of Candida albicans was also evaluated for the two plants with higher antimicrobial behavior. (3) Results: C. chinensis decoction and EO and L. scoparium EO exhibited antifungal activity in Candida spp. In addition to the fact that both C. chinensis decoction and EO proved strong antifungal activity, L. scoparium EO also displayed a relevant inhibitory effect on the dimorphic transition. (4) Conclusions: The results provided support for the potential use of C. chinensis and L. scoparium in the treatment of infections by Candida spp.

Magnolia kobus DC.’ nin yeşil çelikle üretiminde farklı hormon uygulamalarının etkileri

Anavatanı Japonya olan Magnolia kobus DC., Magnoliaceae familyasından, kışın yaprağını döken küçük ağaç formunda bir bitkidir. Formu, aromatik yaprakları, bol miktarda açan pembemsi beyaz çiçekleri ve meyve güzelliği ile Peyzaj Mimarlığı bitkilendirme tasarımlarında tercih edilen bitkilerden biridir. Bu çalışmanın amacı, estetik özelikleri ile etkili olan bu bitkinin çelikle çoğaltılarak kentsel peyzajda kullanımının teşvik edilmesidir. Çalışmada, farklı hormon uygulamalarının Magnolia kobus’un yeşil çeliklerinin köklenme başarısı üzerine etkisi araştırılmıştır. Çeliklere, IBA (Indol-3-bütrik asit), IAA (Indol-3-asetik asit) ve NAA (Naftalin asetik asit) hormonların 0 (kontrol), 3000 ppm, 5000 ppm ve 8000 ppm dozları uygulanmıştır. Çelikler sera koşulları altında (20±2 ºC hava sıcaklığı, 25±2 ºC köklendirme masası alt sıcaklığı, %70±2 nem) perlit ortamına dikilmişlerdir. Yaklaşık 4 ay sonra çelikler sökülerek köklenme oranı (%) ve kök uzunlukları (cm) belirlenmiştir. Çalışmanın sonucunda en yüksek köklenme yüzdesi (%60) IBA hormonunun 8000 ppm dozuyla işlem görmüş çeliklerinde elde edilmiştir. Çeliklerdeki en yüksek kök uzunluğu değerleri IAA 3000 ppm ve 5000 ppm dozla işlem görmüş çeliklerde tespit edilmiştir. Yapılan varyans analizi sonucuna göre hormon uygulamalarının köklenme üzerine anlamlı bir etkisi olduğu tespit edilmiştir (P: 0,000 ˂ 0,05).

Comprehensive Bioinformatics and Expression Analysis of TCP Transcription Factors in Liriodendron chinense Reveals Putative Abiotic Stress Regulatory Roles

As a magnoliid angiosperm, the Liriodendron chinense (Hamsl) Sarg in the Magnoliaceae family is susceptible to external environmental factors. The TEOSINTE BRANCHED 1/CYCLOIDEA/PROLIFERATING CELL FACTORS (TCP) proteins known for their growth and developmental biological roles have been identified in various plant species but not in the Liriodendron chinense. In this study, 15 TCP genes were identified in the L. chinense genome, and categorized into two classes, termed class I (PCF) and class II (CIN and CYC/TB1). A total of 14 TCP genes were located on the 10 chromosomes, and the remaining one, on a contig. Multispecies phylogenetic tree analysis supported the classification of identified LcTCP genes and exhibited that the expansion of the LcTCP gene family was before the angiosperm evolutionary divergence times. Additional gene duplication investigations revealed a purifying selection pressure during evolution history. Moreover, the LcTCP genes were also observed to have various cis-acting elements related to plant growth and development, phytohormone regulations, and abiotic stress responses. Gene expression pattern analysis also paraded that LcTCP genes play a crucial role in abiotic stress regulations. In particular, LcTCP1 in all stresses investigated. Overall, our findings suggest a pivotal role for the TCP gene family during external environmental stresses in L. chinense. This study will provide valuable information on the identification and function of the LcTCPs during abiotic stresses, paving the way for further research on the functional verification of L. chinense TCPs.

Fingerprints of climatic changes through the late Cenozoic in southern Asian flora: Magnolia section Michelia (Magnoliaceae).

Ongoing global warming is a challenge for humankind. A series of drastic climatic changes have been proven to have occurred throughout the Cenozoic based on a variety of geological evidence, which helps to better understand our planet's future climate. Notably, extant biomes have recorded drastic environmental shifts. The climate in southern Asia, which hosts high biodiversity, is deeply impacted by the Asian monsoon. The origins and evolutionary dynamics of biomes occurring between the tropics and sub-tropics in southern Asia have probably been deeply impacted by climatic changes; however, these aspects remain poorly studied. We tested whether the evolutionary dynamics of the above biomes have recorded the drastic, late Cenozoic environmental shifts, by focusing on Magnolia section Michelia of the family Magnoliaceae. We established a fine time-calibrated phylogeny of M. section Michelia based on complete plastid genomes and inferred its ancestral ranges. Finally, we estimated the evolutionary dynamics of this section through time, determining its diversification rate and the dispersal events that occurred between tropical and sub-tropical areas. The tropical origin of M. section Michelia was dated to the late Oligocene; however, the diversification of its core group (i.e. M. section Michelia subsection Michelia) has occurred mainly from the late Miocene onward. Two key evolutionary shifts (dated approx. 8 and approx. 3 million years ago, respectively) were identified, each of them probably in response to drastic climatic changes. Here, we inferred the underlying evolutionary dynamics of biomes in southern Asia, which probably reflect late Cenozoic climatic changes. The occurrence of modern Asian monsoons was probably fundamental for the origin of M. section Michelia; moreover, the occurrence of asymmetric dispersal events between the tropics and sub-tropics hint at an adaptation strategy of M. section Michelia to global cooling, in agreement with the tropical conservatism hypothesis.

A Comprehensive Review of the Main Lignan Components of Schisandra chinensis (North Wu Wei Zi) and Schisandra sphenanthera (South Wu Wei Zi) and the Lignan-Induced Drug-Drug Interactions Based on the Inhibition of Cytochrome P450 and P-Glycoprotein Activities.

Wu Wei Zi is the dried fruit of Schisandra chinensis (Turcz.) Baill. or Schisandra sphenanthera Rehd. et Wils. (family Magnoliaceae). As a homology of medicine and food, it has been widely used in China for thousands of years, to tonify the kidney, and ameliorate neurological, cardiovascular, liver, and gastrointestinal disorders. As its increasing health benefits and pharmacological value, many literatures have reported that the combination of Wu Wei Zi in patients has led to fluctuations in the blood level of the combined drug. Therefore, it is extremely important to evaluate its safety concern such as drug-drug interactions (DDIs) when patients are under the poly-therapeutic conditions. This review summarized the effects of Wu Wei Zi extract and its major lignan components on cytochrome P450 and P-glycoprotein activities, the change of which could induce metabolic DDIs. Our review also elaborated on the differences of the major lignan components of the two Schisandra species, as well as the absorption, distribution, metabolism, and elimination of the major lignans. In conclusion, these results would enhance our understanding of the DDI mechanisms involving Wu Wei Zi, and may potentially untangle some differing and conflicting results in the future.

Genome-wide identification of the Liriodendron chinense WRKY gene family and its diverse roles in response to multiple abiotic stress

BackgroundLiriodendron chinense (Lchi) is a tree species within the Magnoliaceae family and is considered a basal angiosperm. The too low or high temperature or soil drought will restrict its growth as the adverse environmental conditions, thus improving L. chinense abiotic tolerance was the key issues to study. WRKYs are a major family of plant transcription factors known to often be involved in biotic and abiotic stress responses. So far, it is still largely unknown if and how the LchiWRKY gene family is tied to regulating L. chinense stress responses. Therefore, studying the involvement of the WRKY gene family in abiotic stress regulation in L. chinense could be very informative in showing how this tree deals with such stressful conditions.ResultsIn this research, we performed a genome-wide analysis of the Liriodendron chinense (Lchi) WRKY gene family, studying their classification relationships, gene structure, chromosomal locations, gene duplication, cis-element, and response to abiotic stress. The 44 members of the LchiWRKY gene family contain a significant amount of sequence diversity, with their lengths ranging from 525 bp to 40,981 bp. Using classification analysis, we divided the 44 LchiWRKY genes into three phylogenetic groups (I, II, II), with group II then being further divided into five subgroups (IIa, IIb, IIc, IId, IIe). Comparative phylogenetic analysis including the WRKY families from 17 plant species suggested that LchiWRKYs are closely related to the Magnolia Cinnamomum kanehirae WRKY family, and has fewer family members than higher plants. We found the LchiWRKYs to be evenly distributed across 15 chromosomes, with their duplication events suggesting that tandem duplication may have played a major role in LchiWRKY gene expansion model. A Ka/Ks analysis indicated that they mainly underwent purifying selection and distributed in the group IId. Motif analysis showed that LchiWRKYs contained 20 motifs, and different phylogenetic groups contained conserved motif. Gene ontology (GO) analysis showed that LchiWRKYs were mainly enriched in two categories, i.e., biological process and molecular function. Two group IIc members (LchiWRKY10 and LchiWRKY37) contain unique WRKY element sequence variants (WRKYGKK and WRKYGKS). Gene structure analysis showed that most LchiWRKYs possess 3 exons and two different types of introns: the R- and V-type which are both contained within the WRKY domain (WD). Additional promoter cis-element analysis indicated that 12 cis-elements that play different functions in environmental adaptability occur across all LchiWRKY groups. Heat, cold, and drought stress mainly induced the expression of group II and I LchiWRKYs, some of which had undergone gene duplication during evolution, and more than half of which had three exons. LchiWRKY33 mainly responded to cold stress and LchiWRKY25 mainly responded to heat stress, and LchiWRKY18 mainly responded to drought stress, which was almost 4-fold highly expressed, while 5 LchiWRKYs (LchiWRKY5, LchiWRKY23, LchiWRKY14, LchiWRKY27, and LchiWRKY36) responded equally three stresses with more than 6-fold expression. Subcellular localization analysis showed that all LchiWRKYs were localized in the nucleus, and subcellular localization experiments of LchiWRKY18 and 36 also showed that these two transcription factors were expressed in the nucleus.ConclusionsThis study shows that in Liriodendron chinense, several WRKY genes like LchiWRKY33, LchiWRKY25, and LchiWRKY18, respond to cold or heat or drought stress, suggesting that they may indeed play a role in regulating the tree’s response to such conditions. This information will prove a pivotal role in directing further studies on the function of the LchiWRKY gene family in abiotic stress response and provides a theoretical basis for popularizing afforestation in different regions of China.

Formation of a collection of magnolia (Magnoliaceae Juss.) in the Stavropol Botanical Garden

The purpose of the work is to study the ways of forming the collection fund of magnoliaceae in the Stavropol Botanical Garden named after V.V. Skripchinsky (SBG), to assess the current state of the collection and prospects for development. The relevance and practical significance of studying representatives of magnolias comes from the increased needs to expand the assortment of highly ornamental woody plants for landscaping settlements of the Stavropol Territory. The object of the study was the plants of the SBG collection. For reviewing the history of the introduction of magnolias the archival data and reporting documentation were used. Phenological indicators were recorded according to the generally accepted methodology for the botanical gardens of the USSR. The height of the plants was measured with a SUUNTO PM-5 altimeter. The work was carried out in 2020-2022. The SBG has been interested in magnolias since the first years of the garden’s creation (since 1959). As of 2021, there were 8 species and hybrid taxa from two genera of the Magnoliaceae family in the SBG collection, represented by 17 specimens. The life form is characteristic of the studied taxa: large shrubs (Magnolia kobus, M. liliifl ora, M. × soulangeana), low-stemmed (M. kobus, M. kobus var. borealis, M. × loebneri) and tall trees (M. acuminata), sometimes multi-stemmed (Liriodendron tulipifera). The article describes the characteristics of the magnolias available in the collection: their age, size, main phenological phases. The quality of flowering magnolias is influenced by a decrease in temperatures in the early spring period: prolonged cooling causes freezing of generative buds or “rusting” of petals. As a result of long-term study by the staff of M.A. Koltsova, A.F. Koltsov, E.V. Pyatko, the species M. acuminata, M. kobus, M. kobus var. borealis, M. liliiflora are recommended for further use in landscaping in the Stavropol region. In 2021, work continued on the formation of a collection of magnolias: two-year seedlings of 9 varieties and 2 species of deciduous magnolias were obtained for further introduction study.

The evolutionary history of the Caribbean magnolias (Magnoliaceae): Testing species delimitations and biogeographical hypotheses using molecular data

The Caribbean islands provide an ideal setting for studying biodiversity, given their complex geological and environmental history, and their historical and current geographical proximity to the American mainland. Magnolia, a flagship tree genus that has 15 endemic and threatened taxa (12 species and 3 subspecies) on the Caribbean islands, offers an excellent case study to empirically test Caribbean biogeographical hypotheses. We constructed phylogenetic hypotheses to: (1) reveal their evolutionary history, (2) test the current largely morphology-based classification and assess species limits, and (3) investigate major biogeographic hypotheses proposed for the region. Nuclear and chloroplast DNA sequence data of all 15 Caribbean Magnolia taxa are included, supplemented by a selection of American mainland species, and species representing most major clades of the Magnoliaceae family. We constructed phylogenetic hypotheses in a time-calibrated Bayesian framework, supplemented with haplotype network analyses and ancestral range estimations. Genetic synapomorphies in the studied markers confirm the species limits of 14 out of 15 morphologically recognizable Caribbean Magnolia taxa. There is evidence for four colonization events of Magnolia into the Caribbean from the American mainland, which most likely occurred by overwater dispersal, given age estimates of maximum 16 mya for their presence on the Caribbean islands.

Physiological and transcriptome analysis of Magnolia denudata leaf buds during long-term cold acclimation

BackgroundMagonlia denudata is an important perennial tree species of the Magnoliaceae family, known for its ornamental value, resistance to smoke pollution and wind, role in air purification, and robust cold tolerance. In this study, a high-throughput transcriptome analysis of leaf buds was performed, and gene expression following artificial acclimation 22 °C, 4 °C and 0 °C, was compared by RNA sequencing.ResultsOver 426 million clean reads were produced from three libraries (22 °C, 4 °C and 0 °C). A total of 74,503 non-redundant unigenes were generated, with an average length of 1173.7 bp (N50 = 1548). Based on transcriptional results, 357 and 235 unigenes were identified as being upregulated and downregulated under cold stress conditions, respectively. Differentially expressed genes were annotated using Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes pathway analyses. The transcriptomic analysis focused on carbon metabolism and plant hormone signal transduction associated with cold acclimation. Transcription factors such as those in the basic helix-loop-helix and AP2/ERF families were found to play an important role in M. denudata cold acclimation.ConclusionM. denudata exhibits responses to non-freezing cold temperature (4 °C) to increase its cold tolerance. Cold resistance was further strengthened with cold acclimation under freezing conditions (0 °C). Cold tolerance genes, and cold signaling transcriptional pathways, and potential functional key components for the regulation of the cold response were identified in M. denudata. These results provide a basis for further studies, and the verification of key genes involved in cold acclimation responses in M. denudata lays a foundation for developing breeding programs for Magnoliaceae species.

The chromosome-scale genome of Magnolia officinalis provides insight into the evolutionary position of magnoliids

SummaryMagnolia officinalis, a representative tall aromatic tree of the Magnoliaceae family, is a medicinal plant that is widely used in diverse industries from medicine to cosmetics. We report a chromosome-scale draft genome of M. officinalis, in which ∼99.66% of the sequences were anchored onto 19 chromosomes with the scaffold N50 of 76.62 Mb. We found that a high proportion of repetitive sequences was a common feature of three Magnoliaceae with known genomic data. Magnoliids were a sister clade to eudicots-monocots, which provided more support for understanding the phylogenetic position among angiosperms. An ancient duplication event occurred in the genome of M. officinalis and was shared with Lauraceae. Based on RNA-seq analysis, we identified several key enzyme-coding gene families associated with the biosynthesis of lignans in the genome. The construction of the M. officinalis genome sequence will serve as a reference for further studies of Magnolia, as well as other Magnoliaceae.

Integrated RNA and miRNA sequencing analysis reveals a complex regulatory network of Magnolia sieboldii seed germination

Magnolia sieboldii K. Koch (M. sieboldii) is a deciduous Chinese tree species of the Magnoliaceae family with high ornamental, medicinal, and economic benefits. The germination of M. sieboldii seeds under natural conditions is extremely difficult, thereby hindering the cultivation and breeding of this important species. The molecular mechanisms underlying M. sieboldii seed germination remain unclear due to the lack of genomic and transcriptomic resources. Here, we integrated both mRNA and miRNA sequencing to identify the genes and pathways related to M. sieboldii germination. A comprehensive full-length transcriptome containing 158,083 high-quality unigenes was obtained by single-molecule real-time (SMRT) sequencing technology. We identified a total of 13,877 genes that were differentially expressed between non-germinated and germinated seeds. These genes were mainly involved in plant hormone signal transduction and diverse metabolic pathways such as those involving lipids, sugars, and amino acids. Our results also identified a complex regulatory network between miRNAs and their target genes. Taken together, we present the first transcriptome of M. sieboldii and provide key genes and pathways associated with seed germination for further characterization. Future studies of the molecular basis of seed germination will facilitate the genetic improvement M. sieboldii.