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Tamarix hispida Willd. 1816, a crucial native plant species in the arid desert region of northwestern China, plays a significant role in maintaining ecological stability. It is instrumental in addressing soil salinity–alkalinity and heavy metal pollution. This research aims to analyze the phylogenetic divergence pattern and evolutionary history of T. hispida by comparing chloroplast genome structures across different populations. Despite the minimal differences in chloroplast genome structure due to conserved genes and junction regions, sequencing was conducted using the Illumina NovaSeq platform to verify the historical evolutionary processes between different populations, followed by assembly and annotation. The results revealed that the T. hispida chloroplast genome is approximately 156,164–156,186 bp in length, with a quadripartite structure and 131 annotated genes. Phylogenetic analysis indicated two lineages within T. hispida, with a divergence time of 3.15 Ma. These findings emphasize the low genetic diversity in T. hispida and offer valuable insights into its evolutionary past. To effectively protect and manage this species, increased scientific research and monitoring of its genetic diversity are necessary. This study underscores the importance of comprehending the genetic mechanisms behind species divergence to develop informed conservation strategies. [ABSTRACT FROM AUTHOR]

Tamarix hispida Willd. 1816, a crucial native plant species in the arid desert region of northwestern China, plays a significant role in maintaining ecological stability. It is instrumental in addressing soil salinity–alkalinity and heavy metal pollution. This research aims to analyze the phylogenetic divergence pattern and evolutionary history of T. hispida by comparing chloroplast genome structures across different populations. Despite the minimal differences in chloroplast genome structure due to conserved genes and junction regions, sequencing was conducted using the Illumina NovaSeq platform to verify the historical evolutionary processes between different populations, followed by assembly and annotation. The results revealed that the T. hispida chloroplast genome is approximately 156,164–156,186 bp in length, with a quadripartite structure and 131 annotated genes. Phylogenetic analysis indicated two lineages within T. hispida, with a divergence time of 3.15 Ma. These findings emphasize the low genetic diversity in T. hispida and offer valuable insights into its evolutionary past. To effectively protect and manage this species, increased scientific research and monitoring of its genetic diversity are necessary. This study underscores the importance of comprehending the genetic mechanisms behind species divergence to develop informed conservation strategies.

Salt stress is a common abiotic factor that restricts plant growth and development. As a halophyte, Tamarix hispida is a good model plant for exploring salt-tolerance genes and regulatory mechanisms. DNA-binding with one finger (DOF) is an important transcription factor (TF) that influences and controls various signaling substances involved in diverse biological processes related to plant growth and development, but the regulatory mechanisms of DOF TFs in response to salt stress are largely unknown in T. hispida. In the present study, a newly identified Dof gene, ThDOF8 , was cloned from T. hispida , and its expression was found to be induced by salt stress. Transient overexpression of ThDOF8 enhanced T. hispida salt tolerance by enhancing proline levels, and increasing the activities of the antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD). These results were also verified in stably transformed Arabidopsis. Results from TF-centered yeast one-hybrid (Y1H) assays and EMSAs showed that ThDOF8 binds to a newly identified cis -element (TGCG). Expression profiling by gene chip analysis identified four potential direct targets of ThDOF8, namely the cysteine-rich receptor-like kinases genes, CRK10 and CRK26, and two glutamate decarboxylase genes, GAD41 , and GAD42 , and these were further verified by ChIP–quantitative-PCR, EMSAs, Y1H assays, and β-glucuronidase enzyme activity assays. ThDOF8 can bind to the TGCG element in the promoter regions of its target genes, and transient overexpression of ThCRK10 also enhanced T. hispida salt tolerance. On the basis of our results, we propose a new regulatory mechanism model, in which ThDOF8 binds to the TGCG cis -element in the promoter of the target gene CRK10 to regulate its expression and improve salt tolerance in T. hispida. This study provides a basis for furthering our understanding the role of DOF TFs and identifying other downstream candidate genes that have the potential for improving plant salt tolerance via molecular breeding. [ABSTRACT FROM AUTHOR]

GRAS transcription factors belong to the plant-specific protein family. They are not only involved in plant growth and development but also in plant responses to a variety of abiotic stresses. However, to date, the SCL32 (SCARECROW-like 32) gene conferring the desired resistance to salt stresses has not been reported in plants. Here, ThSCL32 , a homologous gene of Arabidopsis thaliana AtSCL32 , was identified. ThSCL32 was highly induced by salt stress in Tamarix hispida. ThSCL32 overexpression in T. hispida gave rise to improved salt tolerance. ThSCL32 -silenced T. hispida plants were more sensitive to salt stress. RNA-seq analysis of transient transgenic T. hispida overexpressing ThSCL32 revealed significantly enhanced ThPHD3 (prolyl-4-hydroxylase domain 3 protein) gene expression. ChIP-PCR further verified that ThSCL32 probably binds to the novel cis -element SBS (ACGTTG) in the promoter of ThPHD3 to activate its expression. In brief, our results suggest that the ThSCL32 transcription factor is involved in salt tolerance in T. hispida by enhancing ThPHD3 expression. [ABSTRACT FROM AUTHOR]

Abstract Background ASR (abscisic acid-, stress-, and ripening-induced) gene family plays a crucial role in responding to abiotic stresses in plants. However, the roles of ASR genes protecting plants against high salt and drought stresses remain unknown in Tamarix hispida. Results In this study, a salt and drought-induced ASR gene, ThASR3, was isolated from Tamarix hispida. Transgenic Arabidopsis overexpressing ThASR3 exhibited stimulating root growth and increasing fresh weight compared with wild-type (WT) plants under both salt and water deficit stresses. To further analyze the gain- and loss-of-function of ThASR3, the transgenic T. hispida plants overexpressing or RNA interference (RNAi)-silencing ThASR3 were generated using transient transformation. The overexpression of ThASR3 in Tamarix and Arabidopsis plants displayed enhanced reactive oxygen species (ROS) scavenging capability under high salt and osmotic stress conditions, including increasing the activities of antioxidant enzymes and the contents of proline and betaine, and reducing malondialdehyde (MDA) content and electrolyte leakage rates. Conclusion Our results indicate that ThASR3 functions as a positive regulator in Tamarix responses to salt and osmotic stresses and confers multiple abiotic stress tolerances in transgenic plants, which may have an important application value in the genetic improvement of forest tree resistance.

Understanding the molecular mechanisms of seed germination and seedling growth is vital for mining functional genes for the improvement of plant drought in a desert. Tamarix hispida is extremely resistant to drought and soil salinity perennial shrubs or trees. This study was the first to investigate the protein abundance profile of the transition process during the processes of T. hispida seed germination and seedling growth using label-free proteomics approaches. Our data suggested that asynchronous regulation of transcriptomics and proteomics occurs upon short-term seed germination and seedling growth of T. hispida. Enrichment analysis revealed that the main differentially abundant proteins had significant enrichment in stimulus response, biosynthesis, and metabolism. Two delta-1-pyrroline-5-carboxylate synthetases (P5CS), one Ycf3-interacting protein (Y3IP), one low-temperature-induced 65 kDa protein-like molecule, and four peroxidases (PRX) were involved in both water deprivation and hyperosmotic salinity responses. Through a comparative analysis of transcriptomics and proteomics, we found that proteomics may be better at studying short-term developmental processes. Our results support the existence of several mechanisms that enhance tolerance to salinity and drought stress during seedling growth in T. hispida. [ABSTRACT FROM AUTHOR]

Background: ASR (abscisic acid-, stress-, and ripening-induced) gene family plays a crucial role in responding to abiotic stresses in plants. However, the roles of ASR genes protecting plants against high salt and drought stresses remain unknown in Tamarix hispida. Results: In this study, a salt and drought-induced ASR gene, ThASR3, was isolated from Tamarix hispida. Transgenic Arabidopsis overexpressing ThASR3 exhibited stimulating root growth and increasing fresh weight compared with wild-type (WT) plants under both salt and water deficit stresses. To further analyze the gain- and loss-of-function of ThASR3, the transgenic T. hispida plants overexpressing or RNA interference (RNAi)-silencing ThASR3 were generated using transient transformation. The overexpression of ThASR3 in Tamarix and Arabidopsis plants displayed enhanced reactive oxygen species (ROS) scavenging capability under high salt and osmotic stress conditions, including increasing the activities of antioxidant enzymes and the contents of proline and betaine, and reducing malondialdehyde (MDA) content and electrolyte leakage rates. Conclusion: Our results indicate that ThASR3 functions as a positive regulator in Tamarix responses to salt and osmotic stresses and confers multiple abiotic stress tolerances in transgenic plants, which may have an important application value in the genetic improvement of forest tree resistance. [ABSTRACT FROM AUTHOR]

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Salt and drought are considered two major abiotic stresses that have a significant impact on plants. Plant NAC (NAM, ATAF1/2, and CUC2) transcription factors (TFs) have been shown to play vital roles in plant development and responses to various abiotic stresses. ThNAC4, a NAC gene from Tamarix hispida involved in salt and osmotic stress tolerance, was identified and characterized in this study. According to a phylogenetic study, ThNAC4 is a member of NAC subfamily II. Subcellular localization analysis showed that ThNAC4 is located in the nucleus, and transcriptional activation experiments demonstrated that ThNAC4 is a transcriptional activator. Transgenic Arabidopsis plants overexpressing ThNAC4 exhibited improved salt and osmotic tolerance, as demonstrated by improved physiological traits. ThNAC4-overexpressing and ThNAC4-silenced T. hispida plants were generated using the transient transformation method and selected for gain- and loss-of-function analysis. The results showed that overexpression of ThNAC4 in transgenic Tamarix and Arabidopsis plants increased the activities of antioxidant enzymes (SOD, POD, and GST) and osmoprotectant (proline and trehalose) contents under stress conditions. These findings suggest that ThNAC4 plays an important physiological role in plant abiotic stress tolerance by increasing ROS scavenging ability and improving osmotic potential. [ABSTRACT FROM AUTHOR]

Abstract Background Seed germination is a series of ordered physiological and morphogenetic processes and a critical stage in plant life cycle. Tamarix hispida is one of the most salt-tolerant plant species; however, its seed germination has not been analysed using combined transcriptomics and metabolomics. Results Transcriptomic sequencing and widely targeted metabolomics were used to detect the transcriptional metabolic profiles of T. hispida at different stages of seed germination and young seedling growth. Transcriptomics showed that 46,538 genes were significantly altered throughout the studied development period. Enrichment study revealed that plant hormones, such as auxin, ABA, JA and SA played differential roles at varying stages of seed germination and post-germination. Metabolomics detected 1022 metabolites, with flavonoids accounting for the highest proportion of differential metabolites. Combined analysis indicated that flavonoid biosynthesis in young seedling growth, such as rhoifolin and quercetin, may improve the plant’s adaptative ability to extreme desert environments. Conclusions The differential regulation of plant hormones and the accumulation of flavonoids may be important for the seed germination survival of T. hispida in response to salt or arid deserts. This study enhanced the understanding of the overall mechanism in seed germination and post-germination. The results provide guidance for the ecological value and young seedling growth of T. hispida.

NAC transcription factors play a significant role in regulating plant responses to biological processes and environmental stresses. Our previous study revealed 21 ThNAC proteins, and ThNAC13 is a nuclear protein that responds to saline stress in Tamarix hispida. To determine whether ThNAC13 regulates downstream genes, RNA sequencing (RNA-seq) and DNA affinity purification sequencing (DAP-seq) were used to identify the binding sites of ThNAC13 at the whole-genome level. In RNAi-silenced ThNAC13 transgenic Tamarix , a total of 4 downregulated differentially expressed genes (DEGs) and 114 peaks strongly associated with four different motifs were identified compared with those in empty vector transgenic Tamarix under salt stress. The c48149.graph_c0 gene contains the key domain of the phloem protein 2 (PP2) protein and is a candidate gene downstream of ThNAC13. Yeast one-hybrid (Y1H), chromatin immunoprecipitation (ChIP) and dual-luciferase reporter (LUC) assays were used to identify ThNAC13 as an upstream regulator of ThPP2. Transgenic Tamarix plants in which ThPP2 was transiently expressed or silenced via RNAi were used for functional gain and loss experiments. The ThPP2- overexpressing plants exhibited decreased hydrogen peroxide (H 2 O 2), superoxide (O 2 •−), and electrolyte leakage (EL) and malondialdehyde (MDA) levels and increased superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activity. In contrast, transient RNAi-mediated silencing of ThPP2 in Tamarix had the opposite effect. ThNAC13 binds to the promoter region of the ThPP2 gene and reduces the reactive oxygen species (ROS) accumulation and enhances antioxidant enzyme activity, positively regulating salt stress tolerance in Tamarix. • 4 down-regulated DEGs and 4 different motifs were identified in RNAi-silenced ThNAC13 compare with empty vector transgenic Tamarix under salt stress. • The phloem protein 2 (PP2) protein as a downstream gene by ThNAC13 TFs. • Overexpression of ThPP2 Tamarix decreased the contents of H 2 O 2 , O 2 •−, EL and MDA; induced the activities of SOD, POD and CAT. • In contrast, transiently RNAi-silenced ThPP2 Tamarix showed the opposite result. • ThNAC13 binds to ThPP2 gene through reduces the ROS accumulation and enhances antioxidant enzyme activity to improve salt stress tolerance. [ABSTRACT FROM AUTHOR]

Tamarix hispida Willd. 1816, a crucial native plant species in the arid desert region of northwestern China, plays a significant role in maintaining ecological stability. It is instrumental in addressing soil salinity-alkalinity and heavy metal pollution. This research aims to analyze the phylogenetic divergence pattern and evolutionary history of T. hispida by comparing chloroplast genome structures across different populations. Despite the minimal differences in chloroplast genome structure due to conserved genes and junction regions, sequencing was conducted using the Illumina NovaSeq platform to verify the historical evolutionary processes between different populations, followed by assembly and annotation. The results revealed that the T. hispida chloroplast genome is approximately 156,164-156,186 bp in length, with a quadripartite structure and 131 annotated genes. Phylogenetic analysis indicated two lineages within T. hispida , with a divergence time of 3.15 Ma. These findings emphasize the low genetic diversity in T. hispida and offer valuable insights into its evolutionary past. To effectively protect and manage this species, increased scientific research and monitoring of its genetic diversity are necessary. This study underscores the importance of comprehending the genetic mechanisms behind species divergence to develop informed conservation strategies., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Understanding the molecular mechanisms of seed germination and seedling growth is vital for mining functional genes for the improvement of plant drought in a desert. Tamarix hispida is extremely resistant to drought and soil salinity perennial shrubs or trees. This study was the first to investigate the protein abundance profile of the transition process during the processes of T. hispida seed germination and seedling growth using label-free proteomics approaches. Our data suggested that asynchronous regulation of transcriptomics and proteomics occurs upon short-term seed germination and seedling growth of T. hispida. Enrichment analysis revealed that the main differentially abundant proteins had significant enrichment in stimulus response, biosynthesis, and metabolism. Two delta-1-pyrroline-5-carboxylate synthetases (P5CS), one Ycf3-interacting protein (Y3IP), one low-temperature-induced 65 kDa protein-like molecule, and four peroxidases (PRX) were involved in both water deprivation and hyperosmotic salinity responses. Through a comparative analysis of transcriptomics and proteomics, we found that proteomics may be better at studying short-term developmental processes. Our results support the existence of several mechanisms that enhance tolerance to salinity and drought stress during seedling growth in T. hispida.

Background: Seed germination is a series of ordered physiological and morphogenetic processes and a critical stage in plant life cycle. Tamarix hispida is one of the most salt-tolerant plant species; however, its seed germination has not been analysed using combined transcriptomics and metabolomics. Results: Transcriptomic sequencing and widely targeted metabolomics were used to detect the transcriptional metabolic profiles of T. hispida at different stages of seed germination and young seedling growth. Transcriptomics showed that 46,538 genes were significantly altered throughout the studied development period. Enrichment study revealed that plant hormones, such as auxin, ABA, JA and SA played differential roles at varying stages of seed germination and post-germination. Metabolomics detected 1022 metabolites, with flavonoids accounting for the highest proportion of differential metabolites. Combined analysis indicated that flavonoid biosynthesis in young seedling growth, such as rhoifolin and quercetin, may improve the plant's adaptative ability to extreme desert environments. Conclusions: The differential regulation of plant hormones and the accumulation of flavonoids may be important for the seed germination survival of T. hispida in response to salt or arid deserts. This study enhanced the understanding of the overall mechanism in seed germination and post-germination. The results provide guidance for the ecological value and young seedling growth of T. hispida. [ABSTRACT FROM AUTHOR]

Trehalose is a non-reducing disaccharide with high stability and strong water absorption properties that can improve the resistance of organisms to various abiotic stresses. Trehalose-6-phosphate synthase (TPS) plays important roles in trehalose metabolism and signaling. In this study, the full-length cDNA of ThTPS was cloned from Tamarix hispida Willd. A phylogenetic tree including ThTPS and 11 AtTPS genes from Arabidopsis indicated that the ThTPS protein had a close evolutionary relationship with AtTPS7. However, the function of AtTPS7 has not been determined. To analyze the abiotic stress tolerance function of ThTPS, the expression of ThTPS in T. hispida under salt and drought stress and JA, ABA and GA3 hormone stimulation was monitored by qRT-PCR. The results show that ThTPS expression was clearly induced by all five of these treatments at one or more times, and salt stress caused particularly strong induction of ThTPS in the roots of T. hispida. The ThTPS gene was transiently overexpressed in T. hispida. Both physiological indexes and staining results showed that ThTPS gene overexpression increased salt and osmotic stress tolerance in T. hispida. Overall, the ThTPS gene can respond to abiotic stresses such as salt and drought, and its overexpression can significantly improve salt and osmotic tolerance. These findings establish a foundation to better understand the responses of TPS genes to abiotic stress in plants. [ABSTRACT FROM AUTHOR]

Abstract Background Peroxiredoxins (Prxs) are a large family of antioxidant enzymes that respond to biotic and abiotic stress by decomposing reactive oxygen species (ROS). In this study, the stress tolerance function of the Th2CysPrx gene was further analysed. It lays a foundation for further studies on the salt tolerance molecular mechanism of T. hispida and improved salt tolerance via transgenic plants. Results In this study, the stress tolerance function of the Th2CysPrx gene was further analysed. The results of transgenic tobacco showed higher seed germination rates, root lengths, and fresh weight under salt stress than wild-type tobacco. Simultaneously, physiological indicators of transgenic tobacco and T. hispida showed that Th2CysPrx improved the activities of antioxidant enzymes and enhanced ROS removal ability to decrease cellular damage under salt stress. Moreover, Th2CysPrx improved the expression levels of four antioxidant genes (ThGSTZ1, ThGPX, ThSOD and ThPOD). Conclusions Overall, these results suggested that Th2CysPrx enhanced the salt tolerance of the transgenic plants. These findings lay a foundation for further studies on the salt tolerance molecular mechanism of T. hispida and improved salt tolerance via transgenic plants.

Salt and drought are considered two major abiotic stresses that have a significant impact on plants. Plant NAC (NAM, ATAF1/2, and CUC2) transcription factors (TFs) have been shown to play vital roles in plant development and responses to various abiotic stresses. ThNAC4, a NAC gene from Tamarix hispida involved in salt and osmotic stress tolerance, was identified and characterized in this study. According to a phylogenetic study, ThNAC4 is a member of NAC subfamily II. Subcellular localization analysis showed that ThNAC4 is located in the nucleus, and transcriptional activation experiments demonstrated that ThNAC4 is a transcriptional activator. Transgenic Arabidopsis plants overexpressing ThNAC4 exhibited improved salt and osmotic tolerance, as demonstrated by improved physiological traits. ThNAC4-overexpressing and ThNAC4-silenced T. hispida plants were generated using the transient transformation method and selected for gain- and loss-of-function analysis. The results showed that overexpression of ThNAC4 in transgenic Tamarix and Arabidopsis plants increased the activities of antioxidant enzymes (SOD, POD, and GST) and osmoprotectant (proline and trehalose) contents under stress conditions. These findings suggest that ThNAC4 plays an important physiological role in plant abiotic stress tolerance by increasing ROS scavenging ability and improving osmotic potential.

Stress associated proteins (SAPs), a class of A20/AN1 zinc finger domain-containing proteins, are involved in a variety of biotic and abiotic stress responses in plants. However, little is known about the SAP gene family and their functions in Tamarix hispida. In this study, we isolated and characterized 11 SAPs from T. hispida. The expression patterns of ThSAPs were analyzed under various stresses (salt and drought) and phytohormone treatment (SA, ABA and MeJA) using real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR). Most ThSAPs exhibited transcriptional responses to abiotic stresses and phytohormones. Among these ThSAPs , ThSAP6 was significantly induced by salt stress. Gain-and loss-of-function analyses revealed that ThSAP6 was a positive regulator of salt stress response. Overexpression of ThSAP6 in T. hispida increased antioxidant enzymes activity and proline content and decreased reactive oxygen species (ROS) accumulation and cell membrane damage under salt stress, while the opposite physiological changes were observed in ThSAP6 -RNAi (RNA interference) lines. This study provides a comprehensive description of the SAP gene family in T. hispida , and demonstrates that ThSAP6 is a potential candidate for biotechnological approaches to improve salt tolerance in plants. • Eleven SAP genes were identified and characterized in Tamarix hispida. • ThSAP genes were regulated by abiotic stresses and hormone treatments. • ThSAP6 overexpression enhanced the ROS scavenging capacity to reduce cell damage. • ThSAP6 can improve the salt tolerance of Tamarix hispida. [ABSTRACT FROM AUTHOR]

The CONSTANS-LIKE (COL) transcription factor has been reported to play important roles in regulating plant flowering and the response to abiotic stress. To clone and screen COL genes with excellent salt tolerance from the woody halophyte Tamarix hispida, 8 ThCOL genes were identified in this study. The expression patterns of these genes under different abiotic stresses (high salt, osmotic, and heavy metal) and abscisic acid (ABA) treatment were detected using quantitative real-time PCR (qRT-PCR). The expression levels of 8 ThCOL genes changed significantly after exposure to one or more stresses, indicating that these genes were all stress-responsive genes and may be involved in the stress resistance response of T. hispida. In particular, the expression level of ThCOL2 changed significantly at most time points in the roots and leaves of T. hispida under salt stress and after ABA treatments, which may play an important role in the response process of salt stress through a mechanism dependent on the ABA pathway. The recombinant vectors pROKII–ThCOL2 and pFGC5941–ThCOL2 were constructed for the transient transformation of T. hispida, and the transient infection of T. hispida with the pROKII empty vector was used as the control to further verify whether the ThCOL2 gene was involved in the regulation of the salt tolerance response of T. hispida. Overexpression of the ThCOL2 gene in plants under 150 mM NaCl stress increased the ability of transgenic T. hispida cells to remove reactive oxygen species (ROS) by regulating the activity of protective enzymes and promoting a decrease in the accumulation of O2– and H2O2, thereby reducing cell damage or cell death and enhancing salt tolerance. The ThCOL2 gene may be a candidate gene associated with excellent salt tolerance. Furthermore, the expression levels of some genes related to the ABA pathway were analyzed using qRT-PCR. The results showed that the expressions of ThNCED1 and ThNCED4 were significantly higher, and the expressions of ThNCED3, ThZEP, and ThAAO3 were not significantly altered in OE compared with CON under normal conditions. But after 24 h of salt stress, the expressions of all five studied genes all were lower than the normal condition. In the future, the downstream genes directly regulated by the ThCOL2 transcription factor will be searched and identified to analyze the salt tolerance regulatory network of ThCOL2.

The CONSTANS-LIKE (COL) transcription factor has been reported to play important roles in regulating plant flowering and the response to abiotic stress. To clone and screen COL genes with excellent salt tolerance from the woody halophyte Tamarix hispida , 8 ThCOL genes were identified in this study. The expression patterns of these genes under different abiotic stresses (high salt, osmotic, and heavy metal) and abscisic acid (ABA) treatment were detected using quantitative real-time PCR (qRT-PCR). The expression levels of 8 ThCOL genes changed significantly after exposure to one or more stresses, indicating that these genes were all stress-responsive genes and may be involved in the stress resistance response of T. hispida. In particular, the expression level of ThCOL2 changed significantly at most time points in the roots and leaves of T. hispida under salt stress and after ABA treatments, which may play an important role in the response process of salt stress through a mechanism dependent on the ABA pathway. The recombinant vectors pROKII– ThCOL2 and pFGC5941– ThCOL2 were constructed for the transient transformation of T. hispida , and the transient infection of T. hispida with the pROKII empty vector was used as the control to further verify whether the ThCOL2 gene was involved in the regulation of the salt tolerance response of T. hispida. Overexpression of the ThCOL2 gene in plants under 150 mM NaCl stress increased the ability of transgenic T. hispida cells to remove reactive oxygen species (ROS) by regulating the activity of protective enzymes and promoting a decrease in the accumulation of O2– and H2O2, thereby reducing cell damage or cell death and enhancing salt tolerance. The ThCOL2 gene may be a candidate gene associated with excellent salt tolerance. Furthermore, the expression levels of some genes related to the ABA pathway were analyzed using qRT-PCR. The results showed that the expressions of ThNCED1 and ThNCED4 were significantly higher, and the expressions of ThNCED3 , ThZEP , and ThAAO 3 were not significantly altered in OE compared with CON under normal conditions. But after 24 h of salt stress, the expressions of all five studied genes all were lower than the normal condition. In the future, the downstream genes directly regulated by the ThCOL2 transcription factor will be searched and identified to analyze the salt tolerance regulatory network of ThCOL2. [ABSTRACT FROM AUTHOR]

The salt overly sensitive (SOS) signal transduction pathway is one of the most highly studied salt tolerance pathways in plants. However, the molecular mechanism of the salt stress response in Tamarix hispida has remained largely unclear. In this study, five SOS genes (ThSOS1–ThSOS5) from T. hispida were cloned and characterized. The expression levels of most ThSOS genes significantly changed after NaCl, PEG6000, and abscisic acid (ABA) treatment in at least one organ. Notably, the expression of ThSOS3 was significantly downregulated after 6 h under salt stress. To further analyze ThSOS3 function, ThSOS3 overexpression and RNAi-mediated silencing were performed using a transient transformation system. Compared with controls, ThSOS3-overexpressing transgenic T. hispida plants exhibited greater reactive oxygen species (ROS)-scavenging capability and antioxidant enzyme activity, lower malondialdehyde (MDA) and H2O2 levels, and lower electrolyte leakage rates under salt stress. Similar results were obtained for physiological parameters in transgenic Arabidopsis, including H2O2 and MDA accumulation, superoxide dismutase (SOD) and peroxidase (POD) activity, and electrolyte leakage. In addition, transgenic Arabidopsis plants overexpressing ThSOS3 displayed increased root growth and fresh weight gain under salt stress. Together, these data suggest that overexpression of ThSOS3 confers salt stress tolerance on plants by enhancing antioxidant enzyme activity, improving ROS-scavenging capability, and decreasing the MDA content and lipid peroxidation of cell membranes. These results suggest that ThSOS3 might play an important physiological role in salt tolerance in transgenic T. hispida plants. This study provides a foundation for further elucidation of salt tolerance mechanisms involving ThSOSs in T. hispida.

The salt overly sensitive (SOS) signal transduction pathway is one of the most highly studied salt tolerance pathways in plants. However, the molecular mechanism of the salt stress response in Tamarix hispida has remained largely unclear. In this study, five SOS genes (ThSOS1 – ThSOS5) from T. hispida were cloned and characterized. The expression levels of most ThSOS genes significantly changed after NaCl, PEG6000, and abscisic acid (ABA) treatment in at least one organ. Notably, the expression of ThSOS3 was significantly downregulated after 6 h under salt stress. To further analyze ThSOS3 function, ThSOS3 overexpression and RNAi-mediated silencing were performed using a transient transformation system. Compared with controls, ThSOS3 -overexpressing transgenic T. hispida plants exhibited greater reactive oxygen species (ROS)-scavenging capability and antioxidant enzyme activity, lower malondialdehyde (MDA) and H2O2 levels, and lower electrolyte leakage rates under salt stress. Similar results were obtained for physiological parameters in transgenic Arabidopsis, including H2O2 and MDA accumulation, superoxide dismutase (SOD) and peroxidase (POD) activity, and electrolyte leakage. In addition, transgenic Arabidopsis plants overexpressing ThSOS3 displayed increased root growth and fresh weight gain under salt stress. Together, these data suggest that overexpression of ThSOS3 confers salt stress tolerance on plants by enhancing antioxidant enzyme activity, improving ROS-scavenging capability, and decreasing the MDA content and lipid peroxidation of cell membranes. These results suggest that ThSOS3 might play an important physiological role in salt tolerance in transgenic T. hispida plants. This study provides a foundation for further elucidation of salt tolerance mechanisms involving ThSOS s in T. hispida. [ABSTRACT FROM AUTHOR]

Nanoparticles are known to have a distinctive interaction at the molecular level with biological systems and widely used in cancer treatment. Silver nanoparticles (AgNPs) was characterized by UV-visible, XRD and TEM. The phytochemical screening was performed to study the plant chemical compounds. The cytotoxic properties of AgNPs on breast cancer cells (MCF-7 line) have obtained using MTT assay. The potent inhibitory effects of nanoparticles on Cyclin-D1 gene expression were demonstrated by western blotting. The AgNPs (7-10 nm) were synthesized using Tamarix hispida. The phytochemical analysis showed that T. hispida is rich in proteins, carbohydrates, and alkaloids. The western blot analysis showed that the AgNPs inhibits the Cyclin D1 expression and decreases cell proliferation. In conclusion, the results provide a promising approach for designing a new AgNPs-mediated drug delivery study due to the remarkable exhibition of cytotoxicity activity for cancer therapy. [ABSTRACT FROM AUTHOR]

Background: Peroxiredoxins (Prxs) are a large family of antioxidant enzymes that respond to biotic and abiotic stress by decomposing reactive oxygen species (ROS). In this study, the stress tolerance function of the Th2CysPrx gene was further analysed. It lays a foundation for further studies on the salt tolerance molecular mechanism of T. hispida and improved salt tolerance via transgenic plants. Results: In this study, the stress tolerance function of the Th2CysPrx gene was further analysed. The results of transgenic tobacco showed higher seed germination rates, root lengths, and fresh weight under salt stress than wild-type tobacco. Simultaneously, physiological indicators of transgenic tobacco and T. hispida showed that Th2CysPrx improved the activities of antioxidant enzymes and enhanced ROS removal ability to decrease cellular damage under salt stress. Moreover, Th2CysPrx improved the expression levels of four antioxidant genes (ThGSTZ1, ThGPX, ThSOD and ThPOD). Conclusions: Overall, these results suggested that Th2CysPrx enhanced the salt tolerance of the transgenic plants. These findings lay a foundation for further studies on the salt tolerance molecular mechanism of T. hispida and improved salt tolerance via transgenic plants. [ABSTRACT FROM AUTHOR]

Histone deacetylases (HDACs) play an important regulatory role in plant response to biotic and abiotic stresses. They improve plant stress resistance by increasing the degree of histone acetylation associated with stress-responsive genes. SAP30BP, a human transcriptional regulatory protein, can increase histone deacetylase activity by regulating the deacetylation levels of lysines 9 and 14 in histone H3. In this study, a ThSAP30BP gene was cloned and characterized from Tamarix hispida (a kind of woody halophyte). The expression patterns of ThSAP30BP under different abiotic stresses and hormone treatments were detected by qRT-PCR. The results showed that ThSAP30BP was significantly upregulated at most time points under various stress treatments, suggesting that ThSAP30BP may be related to the abiotic stress response of T. hispida. To further analyze the salt stress resistance function of the ThSAP30BP gene, the plant overexpression vector pROKII- ThSAP30BP was instantaneously constructed and transformed into T. hispida. Meanwhile, the empty vector pROKII was also transformed as a control. The activities of SOD and POD, the contents of H 2 O 2 and MDA, the relative conductance and the staining of NBT, DAB and Evans blue were analyzed and compared under salt stress. The results showed that the overexpression of ThSAP30BP in T. hispida reduced the accumulation of ROS in plants and the cell death rate under salt stress. These results suggested that ThSAP30BP may play an important physiological role in salt tolerance of T. hispida. • ThSAP30BP was localized in the nucleus and has transactivation activity. • ThSAP30BP gene can respond to three abiotic stresses and two hormone treatments. • ThSAP30BP overexpression increased ROS-scavenging capability and decreasing lipid peroxidation in cell membrane. • ThSAP30BP could effectively enhance the tolerance of transgenic T. hispida to salt stress. [ABSTRACT FROM AUTHOR]

Heat shock transcription factors (HSFs) play critical roles in several types of environmental stresses. However, the detailed regulatory mechanisms in response to salt stress are still largely unknown. In this study, we examined the salt-induced transcriptional responses of ThHSFA1-ThWRKY4 in Tamarix hispida and their functions and regulatory mechanisms in salt tolerance. ThHSFA1 protein acts as an upstream regulator that can directly activate ThWRKY4 expression by binding to the heat shock element (HSE) of the ThWRKY4 promoter using yeast one-hybrid (Y1H), chromatin immunoprecipitation (ChIP), and dual-luciferase reporter assays. ThHSFA1 and ThWRKY4 expression was significantly induced by salt stress and abscisic acid (ABA) treatment in the roots and leaves of T. hispida. ThHSFA1 is a nuclear-localized protein with transactivation activity at the C-terminus. Compared to nontransgenic plants, transgenic plants overexpressing ThHSFA1 displayed enhanced salt tolerance and exhibited reduced reactive oxygen species (ROS) levels and increased antioxidant enzyme activity levels under salt stress. Therefore, we further concluded that ThHSFA1 mediated the regulation of ThWRKY4 in response to salt stress in T. hispida.

GRAS (GAI, RGA and SCR) domain proteins are plant-specific transcriptional regulators that play roles in developmental processes and stress responses. However, the function and molecular regulatory networks of woody plant GRAS under various physiological conditions are still unclear. As a step toward understanding the GRAS function in plants under diverse environmental stimuli, a total of 12 GRAS genes from Tamarix hispida were identified and characterized. Sequence analysis showed that most of these ThGRASs contained a complete GRAS DNA-binding domain and a variable N-terminal region. Phylogenetic analysis revealed that these GRAS members were divided into PAT1, SHR, LISCL, DLT and DELLA groups. The expressions of each individual GRAS under various abiotic stress conditions or hormone treatments were investigated by real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR). qRT-PCR results showed that these ThGRASs were all differentially expressed in the roots or leaves of T. hispida under abiotic stress and hormone treatment, especially ThGRAS3, ThGRAS5, ThGRAS6, ThGRAS7 and ThGRAS10 genes, indicating that these genes were involved in abiotic stress responses and signaling pathways. This study provides a basis for the elucidation of the function of GRAS genes for future works. [ABSTRACT FROM AUTHOR]

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

WRKY proteins are a large family of transcription factors that are involved in diverse developmental processes and abiotic stress responses in plants. However, our knowledge of the regulatory mechanisms of WRKYs participation in protein–protein interactions is still fragmentary, and such protein–protein interactions are fundamental in understanding biological networks and the functions of proteins. In this study, we report that a WRKY protein from Tamarix hispida, ThWRKY4, can form both homodimers and heterodimers with ThWRKY2 and ThWRKY3. In addition, ThWRKY2 and ThWRKY3 can both bind to W-box motif with binding affinities similar to that of ThWRKY4. Further, the expression patterns of ThWRKY2 and ThWRKY3 are similar to that of ThWRKY4 when plants are exposed to abscisic acid (ABA). Subcellular localization shows that these three ThWRKY proteins are nuclear proteins. Taken together, these results demonstrate that ThWRKY4 is a dimeric protein that can form functional homodimers or heterodimers that are involved in abiotic stress responses.

The MYB transcription factors (TFs) is a plant TF families, which involves in hormone signal transduction, and abiotic stress tolerance, etc. However, there are few studies on the MYB TFs family and its regulatory mechanism in Tamarix hispida. In this study, 14 MYB genes (named ThMYB1 - ThMYB14) were cloned and characterized from T. hispida. The transcription profiles of ThMYBs in T. hispida under different abiotic stress conditions were monitored using qRT-PCR. Most of studied ThMYBs were significantly downregulated and/or upregulated by salt and osmotic stress, ABA, GA3 and JA treatments in at least one organ. Especially, ThMYB13 was induced in the leaves and roots of T. hispida when exposed to NaCl treatment at all study periods, indicating that it may involve in salt stress. To further study ThMYB13 function, ThMYB13 overexpression and knock-down plants and control plants transformed with an empty pROKII were obtained using a transient transformation system. Overexpression of ThMYB13 in T. hispida displayed the lowest O2-, H2O2 and MDA accumulation, minimal cell death, the most stable K+/Na+ ratio and the lowest electrolyte leakage rate among the three kinds of transient expression in T. hispida. Conversely, the RNAi-silencing, transiently transformed plants displayed the opposite physiological changes. Therefore, ThMYB13 might play a role in salt stress tolerance in transgenic T. hispida plants.

Introduction: Biofilms are communities of microorganisms embedded in a self-produced extracellular polymeric matrix. Bacterial cells are protected from antimicrobial agents in biofilm structure. Biofilms formation cause many problems in industry, medicine and microbial drug resistance; thus it is essential to find new techniques for removing and inhibiting biofilms. This study aimed to examine the antimicrobial effect of Tamarix hispida alcoholic extracts against six pathogenic bacteria in planktonic and biofim forms. Materials and methods: Antimicrobial activities of the plant extracts against the planktonic form of bacteria were evaluated by using the disc diffusion method. MIC and MBC values were determined by a macrobroth dilution technique. Anti-biofilm effects were assessed by microtiter plate method. Results: The results of this study confirmed high ability of T. hispida extracts against the biofilm of tested bacteria and their free-living forms. Methanolic extracts better inhibited bacterial growth and biofilm formation than ethanolic extracts. Anti-biofilm effects of plant extracts were depended on the solvent and extract concentration. The maximum inhibitory effects of T. hispida extracts on biofilm formation, demolish of biofilm structure and inhibition of metabolic activity of bacteria in the biofilm were observed for S. aureus (87/35 %), S. pneumonia (74/49 %) and B. ceruse (88/34 %) respectively. Discussion and conclusion: In this study the capacity of herbal extracts to encountering whit biofilm was demonstrated and it was confirmed that these extracts have interesting potentiality to become active agents of new drugs.

The MYB transcription factors (TFs) is a plant TF families, which involves in hormone signal transduction, and abiotic stress tolerance, etc. However, there are few studies on the MYB TFs family and its regulatory mechanism in Tamarix hispida. In this study, 14 MYB genes (named ThMYB1 - ThMYB14) were cloned and characterized from T. hispida. The transcription profiles of ThMYBs in T. hispida under different abiotic stress conditions were monitored using qRT-PCR. Most of studied ThMYBs were significantly downregulated and/or upregulated by salt and osmotic stress, ABA, GA3 and JA treatments in at least one organ. Especially, ThMYB13 was induced in the leaves and roots of T. hispida when exposed to NaCl treatment at all study periods, indicating that it may involve in salt stress. To further study ThMYB1 3 function, ThMYB1 3 overexpression and knock-down plants and control plants transformed with an empty pROKII were obtained using a transient transformation system. Overexpression of ThMYB1 3 in T. hispida displayed the lowest O2-, H2O2 and MDA accumulation, minimal cell death, the most stable K+/Na+ ratio and the lowest electrolyte leakage rate among the three kinds of transient expression in T. hispida. Conversely, the RNAi-silencing, transiently transformed plants displayed the opposite physiological changes. Therefore, ThMYB1 3 might play a role in salt stress tolerance in transgenic T. hispida plants. [ABSTRACT FROM AUTHOR]

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

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

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

Ethylene-Responsive Factors (ERFs) are plant-specific transcription factors (TFs) involved in multiple biological processes, especially in abiotic stress tolerance. However, the ERFs from woody halophytes that are involved in salt stress have been little studied. In the present investigation, we characterized a subfamily member of ERF TFs from Tamarix hispida , ThCRF1, which responds to salt stress. ThCRF1 is a nuclear protein that binds to the motifs including TTG, DRE and GCC-box. Transient transformation was performed to generate T. hispida overexpressing ThCRF1 and RNA interference (RNAi)-silenced ThCRF1 to analyze its function using gain- and loss-of-function methods. Overexpression of ThCRF1 in T. hispida significantly improved tolerance to salt-shock-induced stress; by contrast, RNAi-silence of ThCRF1 significantly decreased tolerance to salt-shock-induced stress. Further experiments showed that ThCRF1 induces the expression of genes including those encoding pyrroline-5-carboxylate synthetase ( P5CS ), trehalose-6-phosphate synthase ( TPS ), trehalose-6-phosphate phosphatase ( TPP ), superoxide dismutase ( SOD ) and peroxidase ( POD ), which lead to enhanced proline and trehalose levels and increased SOD and POD activities. These results were further confirmed by studying transgenic Arabidopsis plants overexpressing ThCRF1 . Therefore, the results suggested that ThCRF1 improves tolerance to salt-shock-induced stress by enhancing trehalose and proline biosynthesis to adjust the osmotic potential, and by improving SOD and POD activities to increase reactive oxygen species scavenging capability. [ABSTRACT FROM AUTHOR]

Peroxiredoxins (Prxs) are ubiquitous thiol-specific antioxidant enzymes that are critically involved in cell defense and protect cells from oxidative damage. In this study, a putative Type II Prx (ThPrx1) was identified and characterized from Tamarix hispida. The expression of ThPrx1 is highly induced in response to hydrogen peroxide (HO) and methyl viologen (MV) stresses. When expressed ectopically, ThPrx1 showed enhanced tolerance against oxidative stress in yeast and Arabidopsis. In addition, transgenic Arabidopsis plants overexpressing ThPrx1 displayed improved seedling survival rates and increased root growth and fresh weight gain under HO and MV treatments. Moreover, transgenic Arabidopsis plants showed decreased accumulation of HO, superoxide (O ) and malondialdehyde (MDA), increased superoxide dismutase (SOD) activity compared to wild-type (WT) plants under oxidative stress. Moreover, transgenic plants maintained higher photosynthesis efficiency and lower electrolyte leakage rates than that of WT plants under stress conditions. These results clearly indicated that ThPrx1 plays an important role in cellular redox homeostasis under stress conditions, leading to the maintenance of membrane integrity and increased tolerance to oxidative stress. [ABSTRACT FROM AUTHOR]

R2R3-MYB transcription factors play an important role in plant development and response to various environmental stresses. In this study, a new R2R3-MYB gene, named ThRAX2 , was isolated from T. hispida. ThRAX2 has an open reading frame (ORF) of 1191 bp and encodes a protein of 396 amino acids. ThRAX2 was localized in the nucleus. The overexpression of ThRAX2 in Arabidopsis and T. hispida significantly increased Cadmium (Cd) tolerance. Moreover, the accumulation of cadmium in roots and leaves was significantly reduced. The TF-centred Y1H and Y1H results showed that ThRAX2 was able to specifically bind a new cis-element (MYB-T, CTTCCA). The promoters of some Cd-responsive genes, such as ThSOS1 , ThCKX3 , ThCAX3A , ThMYB78 , ThMIP2 , ThTPS4 , and ThSOD2, all contained 1–3 MYB-T sequences. Furthermore, chromatin immunoprecipitation-polymerase chain reaction (ChIP-PCR) and ChIP quantitative (q)PCR showed that the ThRAX2 gene can bind to ThSOS1 , ThCKX3 , ThCAX3A and ThMYB78 promoter fragments, including the MYB-T motif. Meanwhile, the qRT PCR results also showed that the expression trends of ThSOS1 , ThCKX3 , ThCAX3A and ThMYB78 were similar to that of ThRAX2. This finding suggests that Cd tolerance of the ThRAX2 gene may regulate the expression of some downstream genes through specific recognition of the MYB-T motif and participate in regulating intracellular ion homeostasis, transport, and protein activity or enhance antioxidant enzyme activity. This study found a novel cis-acting element that binds ThRAX2 to regulate Cd tolerance, which lays the foundation for the ThRAX2 regulatory mechanism of Cd stress. This study provides a genetic and theoretical basis for the bioremediation of Cd-contaminated land by cultivating transgenic plants in the future. • Overexpression of ThRAX2 significantly increased Cd tolerance. • ThRAX2 was able to specifically bind a new cis-element (CTTCCA). • ThRAX2 gene can bind to 4 genes promoter fragments including the CTTCCA motif. [ABSTRACT FROM AUTHOR]

NAC (NAM, ATAF1/2, and CUC2) proteins play critical roles in many plant biological processes and environmental stress. However, NAC proteins from Tamarix hispida have not been functionally characterized. Here, we studied a NAC gene from T. hispida, ThNAC13, in response to salt and osmotic stresses. ThNAC13 is a nuclear protein with a C-terminal transactivation domain. ThNAC13 can bind to NAC recognized sites and calmodulin-binding NAC (CBNAC) binding element. Overexpression of ThNAC13 in Arabidopsis improved seed germination rate and increased root growth and fresh weight gain under salt or osmotic stress. Transgenic T. hispida plants transiently overexpressing ThNAC13 and with RNAi-silenced ThNAC13 were generated for gain- and loss-of-function experiments. Following exposure to salt or osmotic stress, overexpression of ThNAC13 induced superoxide dismutase (SOD) and peroxidase (POD) activities, chlorophyll and proline contents; decreased the reactive oxygen species (ROS) and malondialdehyde levels; and reduced electrolyte leakage rates in both transgenic Tamarix and Arabidopsis plants. In contrast, RNAi-silenced ThNAC13 showed the opposite results in transgenic Tamarix. Furthermore, ThNAC13 induced the expression of SODs and PODs in transgenic Arabidopsis. These results suggest that ThNAC13 improves salt and osmotic tolerance by enhancing the ROS-scavenging capability and adjusting osmotic potential.

Protein–protein interactions are important for the molecular understanding of the biological processes of proteins. The dimerization of bZIPs (basic leucine zipper proteins) is involved in modifying binding site specificities, altering dimer stability, and permitting a new set of specific protein-to-protein interactions to occur at the promoter. In the present study, we studied the whether ThbZIP1 form homo- and heterodimers using the yeast two-hybrid method. Five bZIP genes were cloned from Tamarix hispida to investigate their interaction with ThbZIP1. Our results showed that ThbZIP1 can form homodimers with itself, and three out of five bZIPs could interact with the ThbZIP1 protein to form heterodimers. Real-time RT-PCR results suggested that these ThbZIPs can all respond to abiotic stresses and abscisic acid (ABA), and shared very similar expression patterns in response to NaCl, ABA or PEG6000. Subcellular localization studies showed that all ThbZIPs are targeted to the nucleus. Our results showed that ThbZIP1 are dimeric proteins, which can form homo- or heterodimers.

Plant specific NAC (NAM, ATAF1/2 and CUC2) transcription factors (TFs) play important roles in response to abiotic stress. In this study, we identified and characterized a NAC protein, ThNAC7, from Tamarix hispida. ThNAC7 is a nuclear localized protein and has transcriptional activation activity. ThNAC7 expression was markedly induced by salt and osmotic stresses. Transiently transformed T. hispida seedlings overexpressing ThNAC7 (OE) or with RNA interference (RNAi) silenced ThNAC7 were generated to investigate abiotic stress tolerance via the gain- and loss- of function. Overexpressing ThNAC7 showed an increased reactive oxygen species (ROS) scavenging capabilities and proline content, which was accomplished by enhancing the activities of superoxide dismutase (SOD) and peroxidase (POD) in transiently transformed T. hispida and stably transformed Arabidopsis plants. Additionally, ThNAC7 activated these physiological changes by regulating the transcription level of P5CS, SOD and POD genes. RNA-sequencing (RNA-seq) comparison between wild-type and ThNAC7-transformed Arabidopsis showed that more than 40 known salt tolerance genes might regulated by ThNAC7, including stress tolerance-related genes and TF genes. The results indicated that ThNAC7 induces the transcription level of genes associated with stress tolerance to enhance salt and osmotic stress tolerance via an increase in osmotic potential and enhanced ROS scavenging.

Aquaporins belong to the highly conserved major intrinsic protein family and are involved in the transcellular membrane transport of water and other small solutes. However, there has been little work on cloning aquaporin (AQP) family genes and characterizing their functions in plants under various environmental stimuli. In this study, a total of 18 full-length AQP genes were identified in Tamarix hispida, a woody halophyte. Sequence analysis showed that most of these AQP proteins have six transmembrane domains connected by five loops. Phylogenetic analysis revealed that the members of the AQP family can be divided into four groups based on their structural characteristics, including plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), NOD26-like intrinsic proteins (NIPs), and small basic intrinsic proteins (SIPs). Furthermore, the expression profiles of AQP genes were analyzed in the roots, stems, and leaves under salinity, drought, heavy metal, and abscisic acid (ABA) treatments using real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays. The results demonstrated that the AQP were involved in abiotic stress responses, indicating that they play important roles in response to abiotic stress and are involved in ABA-dependent stress-signaling pathways. These data will be useful to elucidate the complexity of the AQP gene family and the molecular mechanisms of abiotic stress tolerance. [ABSTRACT FROM AUTHOR]

Identification of the upstream regulators of a gene is important to characterize the transcriptional pathway and the function of the gene. Previously, we found that a zinc finger protein (ThZFP1) is involved in abiotic stress tolerance of Tamarix hispida. In the present study, we further investigated the transcriptional pathway of ThZFP1. Dof motifs are abundant in the ThZFP1 promoter; therefore, we used them to screen for transcriptional regulators of ThZFP1. A Dof protein, ThDof1.4, binds to the Dof motif specifically, and was hypothesized as the upstream regulator of ThZFP1. Further study showed that overexpression of ThDof1.4 in T. hispida activated the expression of GUS controlled by the ThZFP1 promoter. In T. hispida, transient overexpression of ThDof1.4 increased the transcripts of ThZFP1; conversely, transient RNAi-silencing of ThDof1.4 reduced the expression of ThZFP1. Chromatin immunoprecipitation indicated that ThDof1.4 binds to the ThZFP1 promoter. Additionally, ThDof1.4 and ThZFP1 share similar expression patterns in response to salt or drought stress. Furthermore, like ThZFP1, ThDof1.4 could increase the proline level and enhance ROS scavenging capability to improve salt and osmotic stress tolerance. Together, these results suggested that ThDof1.4 and ThZFP1 form a transcriptional regulatory cascade involved in abiotic stress resistance in T. hispida. [ABSTRACT FROM AUTHOR]

NAC (NAM, ATAF1/2, and CUC2) proteins play critical roles in many plant biological processes and environmental stress. However, NAC proteins from Tamarix hispida have not been functionally characterized. Here, we studied a NAC gene from T. hispida, ThNAC13, in response to salt and osmotic stresses. ThNAC13 is a nuclear protein with a C-terminal transactivation domain. ThNAC13 can bind to NAC recognized sites and calmodulin-binding NAC (CBNAC) binding element. Overexpression of ThNAC13 in Arabidopsis improved seed germination rate and increased root growth and fresh weight gain under salt or osmotic stress. Transgenic T. hispida plants transiently overexpressing ThNAC13 and with RNAi-silenced ThNAC13 were generated for gain- and loss-of-function experiments. Following exposure to salt or osmotic stress, overexpression of ThNAC13 induced superoxide dismutase (SOD) and peroxidase (POD) activities, chlorophyll and proline contents; decreased the reactive oxygen species (ROS) and malondialdehyde levels; and reduced electrolyte leakage rates in both transgenic Tamarix and Arabidopsis plants. In contrast, RNAi-silenced ThNAC13 showed the opposite results in transgenic Tamarix. Furthermore, ThNAC13 induced the expression of SODs and PODs in transgenic Arabidopsis. These results suggest that ThNAC13 improves salt and osmotic tolerance by enhancing the ROS-scavenging capability and adjusting osmotic potential. [ABSTRACT FROM AUTHOR]