ScDREB10, an A-5c type of DREB Gene of the Desert Moss Syntrichia caninervis, Confers Osmotic and Salt Tolerances to Arabidopsis

Exploring lipid signaling in plant physiology: From cellular membranes to environmental adaptation

Lipids have evolved as versatile signaling molecules that regulate a variety of physiological processes in plants. Convincing evidence highlights their critical role as mediators in a wide range of plant processes required for survival, growth, development, and responses to environmental conditions such as water availability, temperature changes, salt, pests, and diseases. Understanding lipid signaling as a critical process has helped us expand our understanding of plant biology by explaining how plants sense and respond to environmental cues. Lipid signaling pathways constitute a complex network of lipids, enzymes, and receptors that coordinate important cellular responses and stressing plant biology's changing and adaptable traits. Plant lipid signaling involves a wide range of lipid classes, including phospholipids, sphingolipids, oxylipins, and sterols, each of which contributes differently to cellular communication and control. These lipids function not only as structural components, but also as bioactive molecules that transfer signals. The mechanisms entail the production of lipid mediators and their detection by particular receptors, which frequently trigger downstream cascades that affect gene expression, cellular functions, and overall plant growth. This review looks into lipid signaling in plant physiology, giving an in-depth look and emphasizing its critical function as a master regulator of vital activities.

Pumpkin CmoDREB2A enhances salt tolerance of grafted cucumber through interaction with CmoNAC1 to regulate H2O2 and ABA signaling and K+/Na+ homeostasis

Pumpkin CmoNAC1 enhances salt tolerance in grafted cucumbers. However, the potential interactions with other proteins that may co-regulate salt tolerance alongside CmoNAC1 have yet to be explored. In this study, we identified pumpkin CmoDREB2A as a pivotal transcription factor that interacts synergistically with CmoNAC1 in the co-regulation of salt tolerance. Both transcription factors were observed to bind to each other's promoters, forming a positive regulatory loop of their transcription. Knockout of CmoDREB2A in the root resulted in reduced salt tolerance in grafted cucumbers, whereas overexpression demonstrated the opposite effect. Multiple assays in our study provided evidence of the protein interaction between CmoDREB2A and CmoNAC1. Exploiting this interaction, CmoDREB2A facilitated the binding of CmoNAC1 to the promoters of CmoRBOHD1, CmoNCED6, CmoAKT1;2, and CmoHKT1;1, inducing H2O2 and ABA synthesis and increasing the K+/Na+ ratio in grafted cucumbers under salt stress. Additionally, CmoNAC1 also promoted the binding of CmoDREB2A to CmoHAK5;1/CmoHAK5;2 promoters, further contributing to the K+/Na+ homeostasis. In summary, these findings reveal a crucial mechanism of CmoNAC1 and CmoDREB2A forming a complex enhancing salt tolerance in grafted cucumbers.

Enhancement of salt tolerance of alfalfa: Physiological and molecular responses of transgenic alfalfa plants expressing Syntrichia caninervis-derived ScABI3

Alfalfa (Medicago sativa L.), a perennial forage plant, is a rich source of nutrients such as vitamins, minerals, and proteins. Salt stress, however, impedes its growth. The plant-specific transcription factor abscisic acid insensitive 3 (ABI3) has a critical contribution to the control of abscisic acid (ABA) signaling pathway and abiotic stress response. The gene ScABI3 from Syntrichia caninervis, a moss species tolerant to desiccation, could be considered a potential candidate gene to modify alfalfa's nutritional and growth aspects. However, it remains unclear how ScABI3 affects the salt stress response of transgenic alfalfa. Therefore, we elucidated the role and molecular mechanism of ScABI3 from S. caninervis as an ABA signaling factor in transgenic alfalfa. Our findings demonstrate that ScABI3 overexpression in transgenic alfalfa improves salt tolerance by promoting relative water content, antioxidant enzyme activity, and photosynthetic parameters. Furthermore, the key genes of plant hormone signaling and the classical salt tolerance pathway were activated in ScABI3 transgenic lines under salt stress. Based on these results, ScABI3 could be considered a potentially critical candidate gene to alleviate salt stress in alfalfa. The present study provides valuable insights for developing transgenic crop breeding strategies for saline-alkaline soils.

Transcriptome Profiles Reveals ScDREB10 from Syntrichia caninervis Regulated Phenylpropanoid Biosynthesis and Starch/Sucrose Metabolism to Enhance Plant Stress Tolerance

Desiccation is a kind of extreme form of drought stress and desiccation tolerance (DT) is an ancient trait of plants that allows them to survive tissue water potentials reaching -100 MPa or lower. ScDREB10 is a DREB A-5 transcription factor gene from a DT moss named Syntrichia caninervis, which has strong comprehensive tolerance to osmotic and salt stresses. This study delves further into the molecular mechanism of ScDREB10 stress tolerance based on the transcriptome data of the overexpression of ScDREB10 in Arabidopsis under control, osmotic and salt treatments. The transcriptional analysis of weight gene co-expression network analysis (WGCNA) showed that "phenylpropanoid biosynthesis" and "starch and sucrose metabolism" were key pathways in the network of cyan and yellow modules. Meanwhile, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of differentially expressed genes (DEGs) also showed that "phenylpropanoid biosynthesis" and "starch and sucrose metabolism" pathways demonstrate the highest enrichment in response to osmotic and salt stress, respectively. Quantitative real-time PCR (qRT-PCR) results confirmed that most genes related to phenylpropanoid biosynthesis" and "starch and sucrose metabolism" pathways in overexpressing ScDREB10 Arabidopsis were up-regulated in response to osmotic and salt stresses, respectively. In line with the results, the corresponding lignin, sucrose, and trehalose contents and sucrose phosphate synthase activities were also increased in overexpressing ScDREB10 Arabidopsis under osmotic and salt stress treatments. Additionally, cis-acting promoter element analyses and yeast one-hybrid experiments showed that ScDREB10 was not only able to bind with classical cis-elements, such as DRE and TATCCC (MYBST1), but also bind with unknown element CGTCCA. All of these findings suggest that ScDREB10 may regulate plant stress tolerance by effecting phenylpropanoid biosynthesis, and starch and sucrose metabolism pathways. This research provides insights into the molecular mechanisms underpinning ScDREB10-mediated stress tolerance and contributes to deeply understanding the A-5 DREB regulatory mechanism.

PtrABR1 Increases Tolerance to Drought Stress by Enhancing Lateral Root Formation in Populus trichocarpa

Roots are the main organ for water uptake and the earliest part of a plant's response to drought, making them of great importance to our understanding of the root system's response to drought. However, little is known about the underlying molecular mechanisms that control root responses to drought stress. Here, we identified and functionally characterized the AP2/ERF family transcription factor (TF) PtrABR1 and the upstream target gene zinc-finger protein TF PtrYY1, which respond to drought stress by promoting the growth and development of lateral roots in Populus trichocarpa. A root-specific induction of PtrABR1 under drought stress was explored. The overexpression of PtrABR1 (PtrABR1-OE) promoted root growth and development, thereby increasing tolerance to drought stress. In addition, PtrYY1 is directly bound to the promoter of PtrABR1 under drought stress, and the overexpression of PtrYY1 (PtrYY1-OE) promoted lateral root growth and development and increased tolerance to drought stress. An RNA-seq analysis of PtrABR1-OE with wild-type (WT) poplar identified PtrGH3.6 and PtrPP2C44, which share the same pattern of expression changes as PtrABR1. A qRT-PCR and cis-element analysis further suggested that PtrGH3.6 and PtrPP2C44 may act as potential downstream targets of PtrABR1 genes in the root response pathway to drought stress. In conclusion, these results reveal a novel drought regulatory pathway in which PtrABR1 regulates the network through the upstream target gene PtrYY1 and the potential downstream target genes PtrGH3.6 and PtrPP2C44, thereby promoting root growth and development and improving tolerance to drought stress.

The DREB transcription factor, a biomacromolecule, responds to abiotic stress by regulating the expression of stress-related genes

Abiotic stress is a crucial factor that affects plant survival and growth and even leads to plant death in severe cases. Transcription factors can enhance the ability of plants to fight against various stresses by controlling the expression of downstream genes. The dehydration response element binding protein (DREB) is the most extensive subfamily of AP2/ERF transcription factors involved in abiotic stress. However, insufficient research on the signal network of DREB transcription factors has limited plant growth and reproduction. Furthermore, field planting of DREB transcription factors and their roles under multiple stress also require extensive research. Previous reports on DREB transcription factors have focused on the regulation of DREB expression and its roles in plant abiotic stress. In recent years, there has been new progress in DREB transcription factors. Here, the structure and classification, evolution and regulation, role in abiotic stress, and application in crops of DREB transcription factors were reviewed. And this paper highlighted the evolution of DREB1/CBF, as well as the regulation of DREB transcription factors under the participation of plant hormone signals and the roles of subgroups in abiotic stress. In the future, it will lay a solid foundation for further study of DREB transcription factors and pave the way for the cultivation of resistant plants.

Genome-Wide Characterization and Expression Analysis of Transcription Factor Families in Desert Moss Syntrichia caninervis under Abiotic Stresses

Transcription factor (TF) families play important roles in plant stress responses. S. caninervis is a new model moss for plant desiccation tolerance studies. Here, we report a high-confidence identification and characterization of 591 TFs representing 52 families that covered all chromosomes in S. caninervis. GO term and KEGG pathway analysis showed that TFs were involved in the regulation of transcription, DNA-templated, gene expression, binding activities, plant hormone signal transduction, and circadian rhythm. A number of TF promoter regions have a mixture of various hormones-related cis-regulatory elements. AP2/ERF, bHLH, MYB, and C2H2-zinc finger TFs were the overrepresented TF families in S. caninervis, and the detailed classification of each family is performed based on structural features. Transcriptome analysis revealed the transcript abundances of some ScAP2/ERF, bHLH, MYB, and C2H2 genes were accumulated in the treated S. caninervis under cold, dehydration, and rehydration stresses. The RT-qPCR results strongly agreed with RNA-seq analysis, indicating these TFs might play a key role in S. caninervis response to abiotic stress. Our comparative TF characterization and classification provide the foundations for functional investigations of the dominant TF genes involved in S. caninervis stress response, as well as excellent stress tolerance gene resources for plant stress resistance breeding.

Transcriptome Reveals the Molecular Mechanism of the ScALDH21 Gene from the Desert Moss Syntrichia caninervis Conferring Resistance to Salt Stress in Cotton

The desert moss Syntrichia caninervis has proven to be an excellent plant material for mining resistance genes. The aldehyde dehydrogenase 21 (ScALDH21) gene from S. caninervis has been shown to confer tolerance to salt and drought, but it is unclear how the transgene ScALDH21 regulates tolerance to abiotic stresses in cotton. In the present work, we studied the physiological and transcriptome analyses of non-transgenic (NT) and transgenic ScALDH21 cotton (L96) at 0 day, 2 days, and 5 days after salt stress. Through intergroup comparisons and a weighted correlation network analysis (WGCNA), we found that there were significant differences between NT and L96 cotton in the plant hormone, Ca2+, and mitogen-activated protein kinase (MAPK) signaling pathways as well as for photosynthesis and carbohydrate metabolism. Overexpression of ScALDH21 significantly increased the expression of stress-related genes in L96 compared to NT cotton under both normal growth and salt stress conditions. These data suggest that the ScALDH21 transgene can scavenge more reactive oxygen species (ROS) in vivo relative to NT cotton and improve cotton resistance to salt stress by increasing the expression of stress-responsive genes, responding quickly to stress stimuli, enhancing photosynthesis and improving carbohydrate metabolism. Therefore, ScALDH21 is a promising candidate gene to improve resistance to salt stress, and the application of this gene in cotton provides new insights into molecular plant breeding.

Transcriptional profiling analysis providing insights into desiccation tolerance mechanisms of the desert moss Syntrichia caninervis

Syntrichia caninervis is a desiccation tolerant moss and is the dominant bryophyte found in biological soil crusts in the Gurbantunggut desert. In this study, we assessed the transcriptome profiles of S. caninervis gametophytes during the dehydration-rehydration (D-R) process (across 9 time points) using Illumina sequencing. In total, 22489 transcripts were identified, including 5337 novel transcripts, that mapped to the reference genome. A total of 12548 transcripts exhibited significant alterations in the D-R samples compared with the control samples. The differentially expressed transcripts (DETs) possessed several enriched Gene Ontology terms, such as "water stress response", "oxidation-reduction process", "membrane metabolism", "photosynthesis", and "transcription factor activity". Moreover, during early dehydration stress, the DETs were significantly enriched in stress-related pathways from the Kyoto Encyclopedia of Genes and Genomes, such as "phenylpropanoid biosynthesis", "alpha-linolenic acid metabolism", and "fructose and mannose metabolism". Photosynthesis-related transcripts (e.g., ScPsa H, ScRubisco, and ScLhcb1) were inhibited during the dehydration treatment and significantly accumulated during the late rehydration period. Most transcripts from the late embryogenesis abundant proteins (LEA) and early light-inducible protein (ELIP) families strongly accumulated at the late dehydration stage. These pathways were positively correlated with the content changes of absolute water content and Fv/Fm values, alongside peroxidase and superoxide dismutase activities. Seven transcription factor families, including AP2-ERF, bHLH, G2-like, MYB, NAC, WRKY, and bZIP, were enriched in DETs during D-R treatment. This study is the first transcriptome analysis using the S. caninervis genome for gene annotation and multigroup D-R treatment points. Our results demonstrated the detailed dynamic changes in the transcriptome of S. caninervis during the D-R process. These results also improve understanding of desiccation tolerant plants' adaptations to desiccation stress at the transcription level and provide promising gene resources for transgenic crop breeding.

Proteomic and Transcriptomic Responses of the Desiccation-Tolerant Moss Racomitrium canescens in the Rapid Rehydration Processes

The moss Racomitrium canescens (R. canescens) has strong desiccation tolerance. It can remain desiccated for years and yet recover within minutes of rehydration. Understanding the responses and mechanisms underlying this rapid rehydration capacity in bryophytes could identify candidate genes that improve crop drought tolerance. We explored these responses using physiology, proteomics, and transcriptomics. Label-free quantitative proteomics comparing desiccated plants and samples rehydrated for 1 min or 6 h suggesting that damage to chromatin and the cytoskeleton had occurred during desiccation, and pointing to the large-scale degradation of proteins, the production of mannose and xylose, and the degradation of trehalose immediately after rehydration. The assembly and quantification of transcriptomes from R. canescens across different stages of rehydration established that desiccation was physiologically stressful for the plants; however, the plants recovered rapidly once rehydrated. According to the transcriptomics data, vacuoles appear to play a crucial role in the early stages of R. canescens recovery. Mitochondria and cell reproduction might recover before photosynthesis; most biological functions potentially restarted after ~6 h. Furthermore, we identified novel genes and proteins related to desiccation tolerance in bryophytes. Overall, this study provides new strategies for analyzing desiccation-tolerant bryophytes and identifying candidate genes for improving plant drought tolerance.

DsDBF1, a Type A-5 DREB Gene, Identified and Characterized in the Moss Dicranum scoparium

Plant dehydration-responsive element binding (DREB) transcription factors (TFs) play important roles during stress tolerance by regulating the expression of numerous genes involved in stresses. DREB TFs have been extensively studied in a variety of angiosperms and bryophytes. To date, no information on the identification and characterization of DREB TFs in Dicranum scoparium has been reported. In this study, a new DBF1 gene from D. scoparium was identified by cloning and sequencing. Analysis of the conserved domain and physicochemical properties revealed that DsDBF1 protein has a classic AP2 domain encoding a 238 amino acid polypeptide with a molecular mass of 26 kDa and a pI of 5.98. Subcellular prediction suggested that DsDBF1 is a nuclear and cytoplasmic protein. Phylogenetic analysis showed that DsDBF1 belongs to group A-5 DREBs. Expression analysis by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) revealed that DsDBF1 was significantly upregulated in response to abiotic stresses such as desiccation/rehydration, exposure to paraquat, CdCl₂, high and freezing temperatures. Taken together, our data suggest that DsDBF1 could be a promising gene candidate to improve stress tolerance in crop plants, and the characterization of TFs of a stress tolerant moss such as D. scoparium provides a better understanding of plant adaptation mechanisms.

Moss transcription factors regulating development and defense responses to stress

Transcription factors control gene expression, leading to regulation of biological processes that determine plant development and adaptation to the environment. Land colonization by plants occurred 450-470 million years ago and was accompanied by an increase in the complexity of transcriptional regulation associated to transcription factor gene expansions. AP2/ERF, bHLH, MYB, NAC, GRAS, and WRKY transcription factor families increased in land plants compared with algae. In angiosperms, they play crucial roles in regulating plant growth and responses to environmental stressors. However, less information is available in bryophytes and only in a few cases is the functional role of moss transcription factors in stress mechanisms known. In this review, we discuss current knowledge of the transcription factor families involved in development and defense responses to stress in mosses and other bryophytes. By exploring and analysing the Physcomitrium patens public database and published transcriptional profiles, we show that a high number of AP2/ERF, bHLH, MYB, NAC, GRAS, and WRKY genes are differentially expressed in response to abiotic stresses and during biotic interactions. Expression profiles together with a comprehensive analysis provide insights into relevant transcription factors involved in moss defenses, and hint at distinct and conserved biological roles between bryophytes and angiosperms.

The DREB A-5 Transcription Factor ScDREB5 From Syntrichia caninervis Enhanced Salt Tolerance by Regulating Jasmonic Acid Biosynthesis in Transgenic Arabidopsis

Salinity is a major limiting factor in crop productivity. Dehydration-responsive element-binding protein (DREB) transcription factors have been widely identified in a variety of plants and play important roles in plant stress responses. Studies on DREBs have primarily focused on the A-1 and A-2 DREB groups, while few have focused on the A-5 group. In this study, we concentrated on ScDREB5, an A-5b type DREB gene from the desiccation-tolerant moss Syntrichia caninervis. ScDREB5 is a transcription factor localized to the nucleus that exhibits transactivation activity in yeast. Ectopic ScDREB5 expression in Arabidopsis thaliana increased seed germination and improved seedling tolerance under salt stress. ScDREB5-overexpression transgenic Arabidopsis lines showed lower methane dicarboxylic aldehyde (MDA) and hydrogen peroxide (H₂O₂) contents, but higher peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities compared to wild plants. Moreover, the transcriptional levels of stress marker genes, including RD29B, COR47, LEA6, LEA7, ERD1, P5CS1, and salt overly sensitive (SOS) genes (SOS1, SOS2, and SOS3), were upregulated in the transgenic lines when subjected to salt treatment. Transcriptome and real-time quantitative PCR (RT-qPCR) analyses indicated that transgenic lines were accompanied by an increased expression of jasmonic acid (JA) biosynthesis genes, as well as a higher JA content under salt stress. Our results suggest that ScDREB5 could improve salt tolerance by enhancing the scavenging abilities of reactive oxygen species (ROS), increasing JA content by upregulating JA synthesis gene expression, regulating ion homeostasis by up-regulating stress-related genes, osmotic adjustment, and protein protection, making ScDREB5 a promising candidate gene for crop salt stress breeding.

Genome-wide promoter analysis, homology modeling and protein interaction network of Dehydration Responsive Element Binding (DREB) gene family in Solanum tuberosum

Dehydration Responsive Element Binding (DREB) regulates the expression of numerous stress-responsive genes, and hence plays a pivotal role in abiotic stress responses and tolerance in plants. The study aimed to develop a complete overview of the cis-acting regulatory elements (CAREs) present in S. tuberosum DREB gene promoters. A total of one hundred and four (104) cis-regulatory elements (CREs) were identified from 2.5kbp upstream of the start codon (ATG). The in-silico promoter analysis revealed variable sets of cis-elements and functional diversity with the predominance of light-responsive (30%), development-related (20%), abiotic stress-responsive (14%), and hormone-responsive (12%) elements in StDREBs. Among them, two light-responsive elements (Box-4 and G-box) were predicted in 64 and 61 StDREB genes, respectively. Two development-related motifs (AAGAA-motif and as-1) were abundant in StDREB gene promoters. Most of the DREB genes contained one or more Myeloblastosis (MYB) and Myelocytometosis (MYC) elements associated with abiotic stress responses. Hormone-responsive element i.e. ABRE was found in 59 out of 66 StDREB genes, which implied their role in dehydration and salinity stress. Moreover, six proteins were chosen corresponding to A1-A6 StDREB subgroups for secondary structure analysis and three-dimensional protein modeling followed by model validation through PROCHECK server by Ramachandran Plot. The predicted models demonstrated >90% of the residues in the favorable region, which further ensured their reliability. The present study also anticipated pocket binding sites and disordered regions (DRs) to gain insights into the structural flexibility and functional annotation of StDREB proteins. The protein association network determined the interaction of six selected StDREB proteins with potato proteins encoded by other gene families such as MYB and NAC, suggesting their similar functional roles in biological and molecular pathways. Overall, our results provide fundamental information for future functional analysis to understand the precise molecular mechanisms of the DREB gene family in S. tuberosum.

Chloroplastic SaNADP-ME4 of C3-C4 Woody Desert Species Salsola laricifolia Confers Drought and Salt Stress Resistance to Arabidopsis

The NADP-malic enzyme (NADP-ME) catalyzes the reversible decarboxylation of L-malate to produce pyruvate, CO2, and NADPH in the presence of a bivalent cation. In addition, this enzyme plays crucial roles in plant developmental and environment responses, especially for the plastidic isoform. However, this isoform is less studied in C3-C4 intermediate species under drought and salt stresses than in C3 and C4 species. In the present study, we characterized SaNADP-ME4 from the intermediate woody desert species Salsola laricifolia. SaNADP-ME4 encoded a protein of 646 amino acids, which was found to be located in the chloroplasts based on confocal imaging. Quantitative real-time PCR analysis showed that SaNADP-ME4 was highly expressed in leaves, followed by stems and roots, and SaNADP-ME4 expression was improved and reached its maximum under the 200 mm mannitol and 100 mm NaCl treatments, respectively. Arabidopsis overexpressing SaNADP-ME4 showed increased root length and fresh weight under mannitol and salt stress conditions at the seedling stage. In the adult stage, SaNADP-ME4 could alleviate the decreased in chlorophyll contents and PSII photochemical efficiency, as well as improve the expression of superoxide dismutase, peroxidase, and pyrroline-5-carboxylate synthase genes to enhance reactive oxygen species scavenging capability and proline levels. Our results suggest that SaNADP-ME4 overexpression in Arabidopsis increases drought and salt stress resistance.

Overexpression of a Banana Aquaporin Gene MaPIP1;1 Enhances Tolerance to Multiple Abiotic Stresses in Transgenic Banana and Analysis of Its Interacting Transcription Factors

Aquaporins can improve the ability of plants to resist abiotic stresses, but the mechanism is still not completely clear. In this research, overexpression of MaPIP1;1 in banana improved tolerance to multiple stresses. The transgenic plants resulted in lower ion leakage and malondialdehyde content, while the proline, chlorophyll, soluble sugar, and abscisic acid (ABA) contents were higher. In addition, under high salt and recovery conditions, the content of Na⁺ and K⁺ is higher, also under recovery conditions, the ratio of K⁺/Na⁺ is higher. Finally, under stress conditions, the expression levels of ABA biosynthesis and response genes in the transgenic lines are higher than those of the wild type. In previous studies, we proved that the MaMADS3 could bind to the promoter region of MaPIP1;1, thereby regulating the expression of MaPIP1;1 and affecting the drought tolerance of banana plants. However, the mechanism of MaPIP1;1 gene response to stress under different adversity conditions might be regulated differently. In this study, we proved that some transcription factor genes, including MaERF14, MaDREB1G, MaMYB1R1, MaERF1/39, MabZIP53, and MaMYB22, showed similar expression patterns with MaPIP1;1 under salt or cold stresses, and their encoded proteins could bind to the promoter region of MaPIP1;1. Here we proposed a novel MaPIP1;1-mediated mechanism that enhanced salt and cold tolerance in bananas. The results of this study have enriched the stress-resistant regulatory network of aquaporins genes and are of great significance for the development of molecular breeding strategies for stress-resistant fruit crops.

The Genetic Regulation of Secondary Metabolic Pathways in Response to Salinity and Drought as Abiotic Stresses

Global development has generated a plethora of unfavorable and adverse environmental factors for the living organisms in the ecosystem. Plants are sessile organisms, and they are crucial to sustain life on earth. Since plants are sessile, they face a great number of environmental challenges related to abiotic stresses, such as temperature fluctuation, drought, salinity, flood and metal contamination. Salinity and drought are considered major abiotic stresses that negatively affect the plants’ growth and production of useful content. However, plants have evolved various molecular mechanisms to increase their tolerance to these environmental stresses. There is a whole complex system of communication (cross-talk) through massive signaling cascades that are activated and modulated in response to salinity and drought. Secondary metabolites are believed to play significant roles in the plant’s response and resistance to salinity and drought stress. Until recently, attempts to unravel the biosynthetic pathways were limited mainly due to the inadequate plant genomics resources. However, recent advancements in generating high-throughput “omics” datasets, computational tools and functional genomics approach integration have aided in the elucidation of biosynthetic pathways of many plant bioactive metabolites. This review gathers comprehensive knowledge of plants’ complex system that is involved in the response and resistance to salinity and water deficit stresses as abiotic stress. Additionally, it offers clues in determining the genes involved in this complex and measures its activity. It covers basic information regarding the signaling molecules involved in salinity and drought resistance and how plant hormones regulate the cross-talking mechanism with emphasis on transcriptional activity. Moreover, it discusses many studies that illustrate the relationship between salinity and drought and secondary metabolite production. Furthermore, several transcriptome analysis research papers of medicinal plants are illustrated. The aim of this review is to be a key for any researcher that is aspiring to study the relationship between salinity and drought stresses and secondary metabolite production at the transcriptome and transcription level.

Systematic analysis of differentially expressed ZmMYB genes related to drought stress in maize

MYB transcription factors play pivotal roles in hormone conduction signaling and abiotic stress response. In this study, 54 differentially expressed ZmMYB genes were identified and comprehensive analyses were conducted including gene's structure, chromosomal localization, phylogenetic tree, motif prediction, cis-elements and expression patterns. The results showed that 54 genes were unevenly distributed on 10 chromosomes and classified into eleven main subgroups by phylogenetic analysis, supported by motif and exon/intron analyses. The mainly stress-related cis-elements were ABRE, ARE, MBS and DRE-core. In addition, 8 core ZmMYB genes were identified by co-expression network. qRT-PCR results showed that the 8 ZmMYB genes exhibited different expression levels under different abiotic stresses, indicating that they were responsive to various abiotic stress. These results will provide insight for further functional investigation of ZmMYB genes.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-021-01013-2.

Chloroplast Localized FIBRILLIN11 Is Involved in the Osmotic Stress Response during Arabidopsis Seed Germination

Simple Summary

The FIBRILLIN11 (FBN11) of Arabidopsis has a lipid-binding FBN domain and a kinase domain. FBN11 is present in chloroplasts and is involved in salt and osmotic stress responses during seed germination. In mannitol, the seed germination rate of the fbn11 mutants significantly reduced compared to that of the wild type. The ABA-dependent and -independent stress response regulating genes were differentially expressed in fbn11 mutants and wild-type when grown in mannitol supplemented medium. These results suggest that chloroplast localized FBN11 is involved in mediating osmotic stress tolerance through the signaling pathway that regulates the stress response in the nucleus.

Abstract

Plants live in ever-changing environments, facing adverse environmental conditions including pathogen infection, herbivore attack, drought, high temperature, low temperature, nutrient deficiency, toxic metal soil contamination, high salt, and osmotic imbalance that inhibit overall plant growth and development. Plants have evolved mechanisms to cope with these stresses. In this study, we found that the FIBRILLIN11 (FBN11) gene in Arabidopsis, which has a lipid-binding FBN domain and a kinase domain, is involved in the plant’s response to abiotic stressors, including salt and osmotic stresses. FBN11 protein localizes to the chloroplast. FBN11 gene expression significantly changed when plants were exposed to the abiotic stress response mediators such as abscisic acid (ABA), sodium chloride (NaCl), and mannitol. The seed germination rates of fbn11 homozygous mutants in different concentrations of mannitol and NaCl were significantly reduced compared to wild type. ABA-dependent and -independent stress response regulatory genes were differentially expressed in the fbn11 mutant compared with wild type when grown in mannitol medium. These results suggest a clear role for chloroplast-localized FBN11 in mediating osmotic stress tolerance via the stress response regulatory signaling pathway in the nucleus.

Propagation of desert moss Syntrichia caninervis in peat pellet: a method for rapidly obtaining large numbers of cloned gametophytes

BACKGROUND

Syntrichia caninervis is a typical desiccation tolerant moss that is a dominant species forming biological soil crusts in the Gurbantunggut Desert. This study investigated the effect of different explants on regeneration potential by propagating them on peat pellet.

RESULT

Juvenile and green leaves can regenerate secondary protonema within one week and shoots in one-half month in peat pellet. Rhizoids have a great ability to regenerate, and similar to leaf regeneration, secondary protonema is the dominant type of regenerant. The process of stem regeneration is similar to that of whole gametophytes. Stems are the most important integral body part during propagation. The whole gametophyte is the best materials for rapidly propagating gametophyte on peat pellet.

CONCLUSION

This article improves the state of our current knowledge of desiccation tolerant moss cultivation, highlighting efforts to effectively obtain a large number of gametophytes through different explant parts. This work provides a useful resource for the study of S. caninervis as well as biocrust restoration.

Transcriptome Analysis Reveals Potential Roles of Abscisic Acid and Polyphenols in Adaptation of Onobrychis viciifolia to Extreme Environmental Conditions in the Qinghai-Tibetan Plateau

A detailed understanding of the molecular mechanisms of plant stress resistance in the face of ever-changing environmental stimuli will be helpful for promoting the growth and production of crop and forage plants. Investigations of plant responses to various single abiotic or biotic factors, or combined stresses, have been extensively reported. However, the molecular mechanisms of plants in responses to environmental stresses under natural conditions are not clearly understood. In this study, we carried out a transcriptome analysis using RNA-sequencing to decipher the underlying molecular mechanisms of Onobrychis viciifolia responding and adapting to the extreme natural environment in the Qinghai-Tibetan Plateau (QTP). The transcriptome data of plant samples collected from two different altitudes revealed a total of 8212 differentially expressed genes (DEGs), including 5387 up-regulated and 2825 down-regulated genes. Detailed analysis of the identified DEGs uncovered that up-regulation of genes potentially leading to changes in hormone homeostasis and signaling, particularly abscisic acid-related ones, and enhanced biosynthesis of polyphenols play vital roles in the adaptive processes of O. viciifolia. Interestingly, several DEGs encoding uridine diphosphate glycosyltransferases, which putatively regulate phytohormone homeostasis to resist environmental stresses, were also discovered. Furthermore, numerous DEGs encoding transcriptional factors, such as members of the myeloblastosis (MYB), homeodomain-leucine zipper (HD-ZIP), WRKY, and nam-ataf1,2-cuc2 (NAC) families, might be involved in the adaptive responses of O. viciifolia to the extreme natural environmental conditions. The DEGs identified in this study represent candidate targets for improving environmental stress resistance of O. viciifolia grown in higher altitudes of the QTP, and can provide deep insights into the molecular mechanisms underlying the responses of this plant species to the extreme natural environmental conditions of the QTP.

Identification and expression analysis of the DREB transcription factor family in pineapple (Ananas comosus (L.) Merr.)

Background

Dehydration responsive element-binding (DREB) transcription factors play a crucial role in plant growth, development and stress responses. Although DREB genes have been characterized in many plant species, genome-wide identification of the DREB gene family has not yet been reported in pineapple (Ananas comosus (L.) Merr.).

Results

Using comprehensive genome-wide screening, we identified 20 AcoDREB genes on 14 chromosomes. These were categorized into five subgroups. AcoDREBs within a group had similar gene structures and domain compositions. Using gene structure analysis, we showed that most AcoDREB genes (75%) lacked introns, and that the promoter regions of all 20 AcoDREB genes had at least one stress response-related cis-element. We identified four genes with high expression levels and six genes with low expression levels in all analyzed tissues. We detected expression changes under abiotic stress for eight selected AcoDREB genes.

Conclusions

This report presents the first genome-wide analysis of the DREB transcription factor family in pineapple. Our results provide preliminary data for future functional analysis of AcoDREB genes in pineapple, and useful information for developing new pineapple varieties with key agronomic traits such as stress tolerance.