Genome-Wide Identification and Expression Analysis of the NAC Gene Family in Kandelia obovata, a Typical Mangrove Plant

Phenotypic adaptation and genomic variation of Kandelia obovata associated with its northern introduction along southeastern coast of China

Introduction

Mangroves play a crucial role within coastal wetland ecosystems, with Kandelia obovata frequently utilized for introduction studies and cultivation research. Investigating the rapid adaptability of K. obovata across diverse environmental conditions offers valuable insights into how mangroves can effectively acclimate to global climate fluctuations.

Methods

In this study, following a common gardenexperiment, we investigated variations in morphological traits between twodistinct populations of K. obovata, Quanzhou (QZ) and Wenzhou (WZ),originating from the same introduction site Zhangzhou (ZZ). Then we performed the whole-genome resequencing on multiple populations along the southern coast of China to assess genetic divergence and diversity patterns in response to environmental factors.

Results

Our findings have uncovered divergent growth-defense trade-off mechanisms employed by these two populations when exposed to varying minimal temperatures in the coldest month within their respective habitats. Moreover, our observations have revealed discernible genetic divergence during the process of environmental acclimatization. Subsequent whole-genome re-sequencing have unveiled a significant decrease in genetic diversity within the northernmost population, suggesting that temperature plays a primary role in shaping genetic variability within the K. obovata species.

Discussion

These findings present new evidence for the rapid adaptation of K. obovata and contributes to our understanding of environmental adaptation characteristics during its introduction to northern regions, which holds significant implications for the conservation and sustainable development of mangroves.

Overexpression of NAC transcription factors from Eremopyrum triticeum promoted abiotic stress tolerance

Eremopyrum triticeum is a typical spring ephemeral species, which in China mainly distributed in the desert regions of northern Xinjiang, and play an important role in the desert ecosystems. E. triticeum has several adaptive characteristics such as short growth rhythms, high photosynthetic efficiency, high seed production, drought and salt resistance. However, the molecular regulatory mechanism of E. triticeum in responses to abiotic stress resistance is still unknown. In this study, two NAC-like transcription factor-encoding genes, EtNAC1 and EtNAC2, were isolated from E. triticeum. The predicted EtNAC1 and EtNAC2 proteins possess a typical NAC DNA-binding domain at the N-terminal region. The qRT-PCR analysis showed that EtNAC1 and EtNAC2 were highly expressed in mature roots of E. triticeum, and were significantly up-regulated under drought, high salt and abscisic acid (ABA) stresses. Subcellular localization analysis in onion epidermal cells revealed that EtNAC1 and EtNAC2 were located in the nucleus. Expression of EtNAC1 and EtNAC2 in yeast cells improved the survival rate of yeast under low temperature, H2O2, high drought and salt stresses. Overexpression of EtNAC1 and EtNAC2 in Arabidopsis thaliana conferred enhanced tolerance to drought and salt stresses, increased ABA sensitivity, and transgenic plants showed higher proline (Pro) content, but lower malondialdehyde content, lower chlorophyll leaching, lower water loss rate and stomatal aperture (width/length) than WT plants. In conclusion, EtNAC1 and EtNAC2 play important roles in abiotic stress responses of E. triticeum, which might have significant potential in crop molecular breeding for abiotic stress tolerance.

Genome-Wide Identification of NAC Gene Family Members of Tree Peony (Paeonia suffruticosa Andrews) and Their Expression under Heat and Waterlogging Stress

An important family of transcription factors (TFs) in plants known as NAC (NAM, ATAF1/2, and CUC2) is crucial for the responses of plants to environmental stressors. In this study, we mined the NAC TF family members of tree peony (Paeonia suffruticosa Andrews) from genome-wide data and analyzed their response to heat and waterlogging stresses in conjunction with transcriptome data. Based on tree peony's genomic information, a total of 48 PsNAC genes were discovered. Based on how similar their protein sequences were, these PsNAC genes were divided into 14 branches. While the gene structures and conserved protein motifs of the PsNAC genes within each branch were largely the same, the cis-acting elements in the promoter region varied significantly. Transcriptome data revealed the presence of five PsNAC genes (PsNAC06, PsNAC23, PsNAC38, PsNAC41, PsNAC47) and one PsNAC gene (PsNAC37) in response to heat and waterlogging stresses, respectively. qRT-PCR analysis reconfirmed the response of these five PsNAC genes to heat stress and one PsNAC gene to waterlogging stress. This study lays a foundation for the study of the functions and regulatory mechanisms of NAC TFs in tree peony. Meanwhile, the NAC TFs of tree peony in response to heat and waterlogging stress were excavated, which is of great significance for the selection and breeding of new tree peony varieties with strong heat and waterlogging tolerance.

SOS1 gene family in mangrove (Kandelia obovata): Genome-wide identification, characterization, and expression analyses under salt and copper stress

BACKGROUND

Salt Overly Sensitive 1 (SOS1), a plasma membrane Na+/H+ exchanger, is essential for plant salt tolerance. Salt damage is a significant abiotic stress that impacts plant species globally. All living organisms require copper (Cu), a necessary micronutrient and a protein cofactor for many biological and physiological processes. High Cu concentrations, however, may result in pollution that inhibits the growth and development of plants. The function and production of mangrove ecosystems are significantly impacted by rising salinity and copper contamination.

RESULTS

A genome-wide analysis and bioinformatics techniques were used in this study to identify 20 SOS1 genes in the genome of Kandelia obovata. Most of the SOS1 genes were found on the plasma membrane and dispersed over 11 of the 18 chromosomes. Based on phylogenetic analysis, KoSOS1s can be categorized into four groups, similar to Solanum tuberosum. Kandelia obovata's SOS1 gene family expanded due to tandem and segmental duplication. These SOS1 homologs shared similar protein structures, according to the results of the conserved motif analysis. The coding regions of 20 KoSOS1 genes consist of amino acids ranging from 466 to 1221, while the exons include amino acids ranging from 3 to 23. In addition, we found that the 2.0 kb upstream promoter region of the KoSOS1s gene contains several cis-elements associated with phytohormones and stress responses. According to the expression experiments, seven randomly chosen genes experienced up- and down-regulation of their expression levels in response to copper (CuCl2) and salt stressors.

CONCLUSIONS

For the first time, this work systematically identified SOS1 genes in Kandelia obovata. Our investigations also encompassed physicochemical properties, evolution, and expression patterns, thereby furnishing a theoretical framework for subsequent research endeavours aimed at functionally characterizing the Kandelia obovata SOS1 genes throughout the life cycle of plants.

Regulation of SmEXPA13 expression by SmMYB1R1-L enhances salt tolerance in Salix matsudana Koidz

Expansins, cell wall proteins, play a significant role in plant stress resistance. Our previous study confirmed the expression of the expansin gene SmEXPA13 from Salix matsudana Koidz. enhanced salt tolerance of plants. This report presented an assay that the expression of SmEXPA13 was higher in the salt-resistant willow variety 9901 than in the salt-sensitive variety Yanjiang. In order to understand the possible reasons, a study of the regulation process was conducted. Despite being cloned from both varieties, SmEXPA13 and its promotor showed no significant differences in the structure and sequence. A transcription factor (TF), SmMYB1R1-L, identified through screening the yeast library of willow cDNA, was found to regulate SmEXPA13. Yeast one-hybrid (Y1H) assay confirmed that SmMYB1R1-L could bind to the MYB element at the -520 bp site on the SmEXPA13 promotor. A dual-luciferase reporter assay also demonstrated that SmMYB1R1-L could greatly activate SmEXPA13 expression. The willow calli with over-expression of SmMYB1R1-L exhibited better physiological performance than the wild type under salt stress. Further testing the expression of SmMYB1R1-L displayed it significantly higher in 9901 willow than that in Yanjiang under salt stress. In conclusion, the high accumulation of SmMYB1R1-L in 9901 willow under salt stress led to the high expression of SmEXPA13, resulting in variations in salt stress resistance among willow varieties. The SmMYB1R1-L/SmEXPA13 cascade module in willow offers a new perspective on plant resistance mechanisms.

CcNAC6 Acts as a Positive Regulator of Secondary Cell Wall Synthesis in Sudan Grass (Sorghum sudanense S.)

The degree of forage lignification is a key factor affecting its digestibility by ruminants such as cattle and sheep. Sudan grass (Sorghum sudanense S.) is a high-quality sorghum forage, and its lignocellulose is mostly stored in the secondary cell wall. However, the secondary cell wall synthesis mechanism of Sudan grass has not yet been studied in depth. To further study the secondary cell wall synthesis mechanism of Sudan grass using established transcriptome data, this study found that CcNAC6, a homologous gene of Arabidopsis AtSND2, is related to the secondary cell wall synthesis of Sudan grass. Accordingly, we constructed a CcNAC6-overexpressing line of Arabidopsis to investigate the function of the CcNAC6 gene in secondary cell wall synthesis. The results showed that the overexpression of the CcNAC6 gene could significantly increase the lignin content of Arabidopsis. Based on subcellular localization analysis, CcNAC6 is found in the nucleus. In addition, yeast two-hybridization screening showed that CcCP1, associated with secondary cell wall synthesis, can interact with CcNAC6. Therefore, the above results indicate that CcNAC6 has a positive regulatory effect on the secondary cell wall synthesis of Sudan grass, and it is speculated that CcNAC6 may be the main regulator of the secondary cell wall synthesis of Sudan grass through its interaction with another regulatory protein, CcCP1. This study provides a theoretical basis and new genetic resources for the creation of new Sudan grass germplasm with a low lignin content.

Transcriptional Control of Seed Life: New Insights into the Role of the NAC Family

Transcription factors (TFs) regulate gene expression by binding to specific sequences on DNA through their DNA-binding domain (DBD), a universal process. This update conveys information about the diverse roles of TFs, focusing on the NACs (NAM-ATAF-CUC), in regulating target-gene expression and influencing various aspects of plant biology. NAC TFs appeared before the emergence of land plants. The NAC family constitutes a diverse group of plant-specific TFs found in mosses, conifers, monocots, and eudicots. This update discusses the evolutionary origins of plant NAC genes/proteins from green algae to their crucial roles in plant development and stress response across various plant species. From mosses and lycophytes to various angiosperms, the number of NAC proteins increases significantly, suggesting a gradual evolution from basal streptophytic green algae. NAC TFs play a critical role in enhancing abiotic stress tolerance, with their function conserved in angiosperms. Furthermore, the modular organization of NACs, their dimeric function, and their localization within cellular compartments contribute to their functional versatility and complexity. While most NAC TFs are nuclear-localized and active, a subset is found in other cellular compartments, indicating inactive forms until specific cues trigger their translocation to the nucleus. Additionally, it highlights their involvement in endoplasmic reticulum (ER) stress-induced programmed cell death (PCD) by activating the vacuolar processing enzyme (VPE) gene. Moreover, this update provides a comprehensive overview of the diverse roles of NAC TFs in plants, including their participation in ER stress responses, leaf senescence (LS), and growth and development. Notably, NACs exhibit correlations with various phytohormones (i.e., ABA, GAs, CK, IAA, JA, and SA), and several NAC genes are inducible by them, influencing a broad spectrum of biological processes. The study of the spatiotemporal expression patterns provides insights into when and where specific NAC genes are active, shedding light on their metabolic contributions. Likewise, this review emphasizes the significance of NAC TFs in transcriptional modules, seed reserve accumulation, and regulation of seed dormancy and germination. Overall, it effectively communicates the intricate and essential functions of NAC TFs in plant biology. Finally, from an evolutionary standpoint, a phylogenetic analysis suggests that it is highly probable that the WRKY family is evolutionarily older than the NAC family.

Characterization of NAC Gene Family in Ammopiptanthus mongolicus and Functional Analysis of AmNAC24, an Osmotic and Cold-Stress-Induced NAC Gene

The NAC family of transcription factors (TFs) is recognized as a significant group within the plant kingdom, contributing crucially to managing growth and development processes in plants, as well as to their response and adaptation to various environmental stressors. Ammopiptanthus mongolicus, a temperate evergreen shrub renowned for its remarkable resilience to low temperatures and drought stress, presents an ideal subject for investigating the potential involvement of NAC TFs in stress response mechanisms. Here, the structure, evolution, and expression profiles of NAC family TFs were analyzed systematically, and a cold and osmotic stress-induced member, AmNAC24, was selected and functionally characterized. A total of 86 NAC genes were identified in A. mongolicus, and these were divided into 15 groups. Up to 48 and 8 NAC genes were generated by segmental duplication and tandem duplication, respectively, indicating that segmental duplication is a predominant mechanism in the expansion of the NAC gene family in A. mongolicus. A considerable amount of NAC genes, including AmNAC24, exhibited upregulation in response to cold and osmotic stress. This observation is in line with the detection of numerous cis-acting elements linked to abiotic stress response in the promoters of A. mongolicus NAC genes. Subcellular localization revealed the nuclear residence of the AmNAC24 protein, coupled with demonstrable transcriptional activation activity. AmNAC24 overexpression enhanced the tolerance of cold and osmotic stresses in Arabidopsis thaliana, possibly by maintaining ROS homeostasis. The present study provided essential data for understanding the biological functions of NAC TFs in plants.

Genome-wide identification, evolution, and expression analysis of the NAC gene family in chestnut (Castanea mollissima)

The NAC gene family is one of the most important transcription factor families specific to plants, responsible for regulating many biological processes, including development, stress response, and signal transduction. However, it has not yet been characterized in chestnut, an important nut tree species. Here, we identified 115 CmNAC genes in the chestnut genome, which were divided into 16 subgroups based on the phylogenetic analysis. Numerous cis-acting elements related to auxin, gibberellin, and abscisic acid were identified in the promoter region of CmNACs, suggesting that they play an important role in the growth and development of chestnut. The results of the collinear analysis indicated that dispersed duplication and whole-genome-duplication were the main drivers of CmNAC gene expansion. RNA-seq data of developmental stages of chestnut nut, bud, and ovule revealed the expression patterns of CmNAC genes. Additionally, qRT-PCR experiments were used to verify the expression levels of some CmNAC genes. The comprehensive analysis of the above results revealed that some CmNAC members may be related to chestnut bud and nut development, as well as ovule fertility. The systematic analysis of this study will help to increase understanding of the potential functions of the CmNAC genes in chestnut growth and development.

NRAMP gene family in Kandelia obovata: genome-wide identification, expression analysis, and response to five different copper stress conditions

Natural resistance-associated macrophage proteins (NRAMPs) are a class of metal transporters found in plants that exhibit diverse functions across different species. Transporter proteins facilitate the absorption, distribution, and sequestration of metallic elements within various plant tissues. Despite the extensive identification of NRAMP family genes in various species, a full analysis of these genes in tree species is still necessary. Genome-wide identification and bioinformatics analysis were performed to understand the roles of NRAMP genes in copper (CuCl2) stress in Kandelia obovata (Ko). In Arachis hypogaea L., Populus trichocarpa, Vitis vinifera, Phaseolus vulgaris L., Camellia sinensis, Spirodela polyrhiza, Glycine max L. and Solanum lycopersicum, a genome-wide study of the NRAMP gene family was performed earlier. The domain and 3D structural variation, phylogenetic tree, chromosomal distributions, gene structure, motif analysis, subcellular localization, cis-regulatory elements, synteny and duplication analysis, and expression profiles in leaves and CuCl2 were all investigated in this research. In order to comprehend the notable functions of the NRAMP gene family in Kandelia obovata, a comprehensive investigation was conducted at the genomic level. This study successfully found five NRAMP genes, encompassing one gene pair resulting from whole-genome duplication and a gene that had undergone segmental duplication. The examination of chromosomal position revealed an unequal distribution of the KoNRAMP genes across chromosomes 1, 2, 5, 7, and 18. The KoNRAMPs can be classified into three subgroups (I, II, and SLC) based on phylogeny and synteny analyses, similar to Solanum lycopersicum. Examining cis-regulatory elements in the promoters revealed five hormone-correlated responsive elements and four stress-related responsive elements. The genomic architecture and properties of 10 highly conserved motifs are similar among members of the NRAMP gene family. The conducted investigations demonstrated that the expression levels of all five genes exhibited alterations in response to different levels of CuCl2 stress. The results of this study offer crucial insights into the roles of KoNRAMPs in the response of Kandelia obovata to CuCl2 stress.

Genome-Wide Identification, Characterization, and Expression Analysis of the Copper-Containing Amine Oxidase Gene Family in Mangrove Kandelia obovata

Copper-containing amine oxidases (CuAOs) are known to have significant involvement in the process of polyamine catabolism, as well as serving crucial functions in plant development and response to abiotic stress. A genome-wide investigation of the CuAO protein family was previously carried out in sweet orange (Citrus sinensis) and sweet cherry (Prunus avium L.). Six CuAO (KoCuAO1-KoCuAO6) genes were discovered for the first time in the Kandelia obovata (Ko) genome through a genome-wide analysis conducted to better understand the key roles of the CuAO gene family in Kandelia obovata. This study encompassed an investigation into various aspects of gene analysis, including gene characterization and identification, subcellular localization, chromosomal distributions, phylogenetic tree analysis, gene structure analysis, motif analysis, duplication analysis, cis-regulatory element identification, domain and 3D structural variation analysis, as well as expression profiling in leaves under five different treatments of copper (CuCl2). Phylogenetic analysis suggests that these KoCuAOs, like sweet cherry, may be subdivided into three subgroups. Examining the chromosomal location revealed an unequal distribution of the KoCuAO genes across four out of the 18 chromosomes in Kandelia obovata. Six KoCuAO genes have coding regions with 106 and 159 amino acids and exons with 4 and 12 amino acids. Additionally, we discovered that the 2.5 kb upstream promoter region of the KoCuAOs predicted many cis elements linked to phytohormones and stress responses. According to the expression investigations, CuCl2 treatments caused up- and downregulation of all six genes. In conclusion, our work provides a comprehensive overview of the expression pattern and functional variety of the Kandelia obovata CuAO gene family, which will facilitate future functional characterization of each KoCuAO gene.

Genome-Wide Identification and Expression Analysis of the Copper Transporter (COPT/Ctr) Gene Family in Kandelia obovata, a Typical Mangrove Plant

The copper transporter (COPT/Ctr) gene family plays a critical part in maintaining the balance of the metal, and many diverse species depend on COPT to move copper (Cu) across the cell membrane. In Arabidopsis thaliana, Oryza sativa, Medicago sativa, Zea mays, Populus trichocarpa, Vitis vinifera, and Solanum lycopersicum, a genome-wide study of the COPT protein family was performed. To understand the major roles of the COPT gene family in Kandelia obovata (Ko), a genome-wide study identified four COPT genes in the Kandelia obovata genome for the first time. The domain and 3D structural variation, phylogenetic tree, chromosomal distributions, gene structure, motif analysis, subcellular localization, cis-regulatory elements, synteny and duplication analysis, and expression profiles in leaves and Cu were all investigated in this research. Structural and sequence investigations show that most KoCOPTs have three transmembrane domains (TMDs). According to phylogenetic research, these KoCOPTs might be divided into two subgroups, just like Populus trichocarpa. KoCOPT gene segmental duplications and positive selection pressure were discovered by universal analysis. According to gene structure and motif analysis, most KoCOPT genes showed consistent exon-intron and motif organization within the same group. In addition, we found five hormones and four stress- and seven light-responsive cis-elements in the KoCOPTs promoters. The expression studies revealed that all four genes changed their expression levels in response to copper (CuCl2) treatments. In summary, our study offers a thorough overview of the Kandelia obovata COPT gene family's expression pattern and functional diversity, making it easier to characterize each KoCOPT gene's function in the future.