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Ray A. Bressan - One of the best experts on this subject based on the ideXlab platform.
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Using Arabidopsis-Related Model Species (ARMS): Growth, Genetic Transformation, and Comparative GenomicsArabidopsis Protocols
Springer, 2014Co-Authors: Giorgia Batelli, Jian-kang Zhu, Francesco Orsini, Ray A. Bressan, Hans J Bohnert, Maheshi Dassanayake, Matilde Paino D’urzo, Albino MaggioAbstract:The Arabidopsis-related model species (ARMS) Thellungiella salsuginea and Thellungiella parvula have generated broad interest in salt stress research. While general growth characteristics of these species are similar to Arabidopsis, some aspects of their life cycle require particular attention in order to obtain healthy plants, with a large production of seeds in a relatively short time. This chapter describes basic procedures for growth, maintenance, and Agrobacterium-mediated transformation of ARMS. Where appropriate, differences in requirements between Thellungiella spp. and Arabidopsis are highlighted, along with basic growth requirements of other less studied candidate model species. Current techniques for comparative genomics analysis between Arabidopsis and ARMS are also described in detai
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Journal of Integrative Plant Biology 2007, 49 (10): 1484–1496 Sodium Stress in the Halophyte Thellungiella halophila and Transcriptional Changes in a thsos1-RNA Interference Line
2013Co-Authors: Qingqiu Gong, Dae-jin Yun, Ray A. Bressan, Alex Ulanov, Quan Zhang, Hans J BohnertAbstract:The plasma membrane Na + /H +-antiporter salt overly sensitive1 (SOS1) from the halophytic Arabidopsis-relative Thellungiella halophila (ThSOS1) shows conserved sequence and domain structure with the orthologous genes from Arabidopsis thaliana and other plants. When expression of ThSOS1 was reduced by RNA interference (RNAi), pronounced characteristics of salt-sensitivity were observed. We were interested in monitoring altered transcriptional responses between Thellungiella wild type and thsos1-4, a representative RNAi line with particular emphasis on root responses to salt stress at 350 mmol/L NaCl, a concentration that is only moderately stressful for mature wild type plants. Transcript profiling revealed several functional categories of genes that were differently affected in wild-type and RNAi plants. Down-regulation of SOS1 resulted in different gene expression even in the absence of stress. The pattern of gene induction in the RNAi plant under salt stress was similar to that of glycophytic Arabidopsis rather than that of wild type Thellungiella. The RNAi plants failed to down-regulate functions that are normally reduced in wild type Thellungiella upon stress and did not up-regulate functions that characterize the Thellungiella salt stress response. Metabolite changes observed in wild type Thellungiella after salt stress were less pronounced or absent in RNAi plants. Transcript and metabolite behavior suggested SOS
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tshkt1 2 a hkt1 homolog from the extremophile arabidopsis relative Thellungiella salsuginea shows k specificity in the presence of nacl
Plant Physiology, 2012Co-Authors: Zahir Ali, Hyewon Hong, Hyeong Cheol Park, Akhtar Ali, Rashid Aman, Anna Kropornicka, Wonkyun Choi, Woo Sik Chung, Woe Yeon Kim, Ray A. BressanAbstract:Cellular Na(+)/K(+) ratio is a crucial parameter determining plant salinity stress resistance. We tested the function of plasma membrane Na(+)/K(+) cotransporters in the High-affinity K(+) Transporter (HKT) family from the halophytic Arabidopsis (Arabidopsis thaliana) relative Thellungiella salsuginea. T. salsuginea contains at least two HKT genes. TsHKT1;1 is expressed at very low levels, while the abundant TsHKT1;2 is transcriptionally strongly up-regulated by salt stress. TsHKT-based RNA interference in T. salsuginea resulted in Na(+) sensitivity and K(+) deficiency. The athkt1 mutant lines overexpressing TsHKT1;2 proved less sensitive to Na(+) and showed less K(+) deficiency than lines overexpressing AtHKT1. TsHKT1;2 ectopically expressed in yeast mutants lacking Na(+) or K(+) transporters revealed strong K(+) transporter activity and selectivity for K(+) over Na(+). Altering two amino acid residues in TsHKT1;2 to mimic the AtHKT1 sequence resulted in enhanced sodium uptake and loss of the TsHKT1;2 intrinsic K(+) transporter activity. We consider the maintenance of K(+) uptake through TsHKT1;2 under salt stress an important component supporting the halophytic lifestyle of T. salsuginea.
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the genome of the extremophile crucifer Thellungiella parvula
Nature Genetics, 2011Co-Authors: Maheshi Dassanayake, Dae-jin Yun, Ray A. Bressan, Jeffrey S Haas, Alvaro Gonzalez Hernandez, Hyewon Hong, Shahjahan AliAbstract:Dong-Ha Oh and colleagues report the draft genome of the extremophile crucifer plant Thellungiella parvula. This species is endemic to highly saline environments subject to extreme temperatures. The genome was primarily assembled using next-generation sequencing data.
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sodium stress in the halophyte Thellungiella halophila and transcriptional changes in a thsos1 rna interference line
Journal of Integrative Plant Biology, 2007Co-Authors: Qingqiu Gong, Dae-jin Yun, Ray A. Bressan, Alex Ulanov, Quan Zhang, Hans J BohnertAbstract:The plasma membrane Na + /H + -antiporter salt overly sensitive1 (SOS1) from the halophytic Arabidopsis-relative Thel- lungiella halophila (ThSOS1) shows conserved sequence and domain structure with the orthologous genes from Arabidopsis thaliana and other plants. When expression of ThSOS1 was reduced by RNA interference (RNAi), pronounced characteristics of salt-sensitivity were observed. We were interested in monitoring altered transcriptional responses between Thellungiella wild type and thsos1-4, a representative RNAi line with particular emphasis on root responses to salt stress at 350 mmol/L NaCl, a concentration that is only moderately stressful for mature wild type plants. Transcript profiling revealed several functional categories of genes that were differently affected in wild-type and RNAi plants. Down-regulation of SOS1 resulted in different gene expression even in the absence of stress. The pattern of gene induction in the RNAi plant under salt stress was similar to that of glycophytic Arabidopsis rather than that of wild type Thellungiella. The RNAi plants failed to down-regulate functions that are normally reduced in wild type Thellungiella upon stress and did not up-regulate functions that characterize the Thellungiella salt stress response. Metabolite changes observed in wild type Thellungiella after salt stress were less pronounced or absent in RNAi plants. Transcript and metabolite behavior suggested SOS1 functions including but also extending its established function as a sodium transporter. The down-regulation of ThSOS1 converted the halophyte Thellungiella into a salt-sensitive plant.
Meiru Li - One of the best experts on this subject based on the ideXlab platform.
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establishment of an efficient agrobacterium tumefaciens mediated leaf disc transformation of Thellungiella halophila
Plant Cell Reports, 2007Co-Authors: Hongqing Li, Jie Xu, Lei Chen, Meiru LiAbstract:Thellungiella halophila is a salt-tolerant close relative of Arabidopsis, which is adopted as a halophytic model for stress tolerance research. We established an Agrobacterium tumefaciens-mediated transformation procedure for T. halophila. Leaf explants of T. halophila were incubated with A. tumefaciens strain EHA105 containing a binary vector pCAMBIA1301 with the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene as a reporter gene. Following co-cultivation, leaf explants were cultured on selective medium containing 10 mg l−1 hygromycin and 500 mg l−1 cefotaxime. Hygromycin-resistant calluses were induced from the leaf explants after 3 weeks. Shoot regeneration was achieved after transferring the calluses onto fresh medium of the same composition. Finally, the shoots were rooted on half strength MS basal medium supplemented with 10 mg l−1 hygromycin. Incorporation and expression of the transgenes were confirmed by PCR, Southern blot analysis and GUS histochemical assay. Using this protocol, transgenic T. halophila plants can be obtained in approximately 2 months with a high transformation frequency of 26%.
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establishment of an efficient agrobacterium tumefaciens mediated leaf disc transformation of Thellungiella halophila
Plant Cell Reports, 2007Co-Authors: Hongqing Li, Jie Xu, Lei Chen, Meiru LiAbstract:Thellungiella halophila is a salt-tolerant close relative of Arabidopsis, which is adopted as a halophytic model for stress tolerance research. We established an Agrobacterium tumefaciens-mediated transformation procedure for T. halophila. Leaf explants of T. halophila were incubated with A. tumefaciens strain EHA105 containing a binary vector pCAMBIA1301 with the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene as a reporter gene. Following co-cultivation, leaf explants were cultured on selective medium containing 10 mg l−1 hygromycin and 500 mg l−1 cefotaxime. Hygromycin-resistant calluses were induced from the leaf explants after 3 weeks. Shoot regeneration was achieved after transferring the calluses onto fresh medium of the same composition. Finally, the shoots were rooted on half strength MS basal medium supplemented with 10 mg l−1 hygromycin. Incorporation and expression of the transgenes were confirmed by PCR, Southern blot analysis and GUS histochemical assay. Using this protocol, transgenic T. halophila plants can be obtained in approximately 2 months with a high transformation frequency of 26%.
Dirk K Hincha - One of the best experts on this subject based on the ideXlab platform.
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natural variation in freezing tolerance and cold acclimation response in arabidopsis thaliana and related species
Advances in Experimental Medicine and Biology, 2018Co-Authors: Ellen Zuther, Joachim Kopka, Alexander Erban, Dirk K HinchaAbstract:During low-temperature exposure, temperate plant species increase their freezing tolerance in a process termed cold acclimation. The molecular mechanisms involved in cold acclimation have been mostly investigated in Arabidopsis thaliana. In addition, other Brassicaceae species related to A. thaliana have been employed in recent years to study plant stress responses on a phylogenetically broader basis and in some cases with extremophile species with a much higher stress tolerance. In this paper, we briefly summarize cold acclimation responses in A. thaliana and current knowledge about cold acclimation in A. thaliana relatives with special emphasis on Eutrema salsugineum and two closely related Thellungiella species. We then present a transcriptomic and metabolomic analysis of cold acclimation in five A. thaliana and two E. salsugineum accessions that differ widely in their freezing tolerance. Differences in the cold responses of the two species are discussed.
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salt stress responses in a geographically diverse collection of eutrema Thellungiella spp accessions
Functional Plant Biology, 2016Co-Authors: Yang Ping Lee, Ellen Zuther, Joachim Kopka, Alexander Erban, Christian Funk, Karin Kohl, Dirk K HinchaAbstract:Salinity strongly impairs plant growth and development. Natural genetic variation can be used to dissect complex traits such as plant salt tolerance. We used 16 accessions of the halophytic species Eutrema salsugineum (previously called Thellungiella salsuginea (Pallas) O.E.Schulz, Thellungiella halophila (C.A.Meyer) O.E. Schulz and Thellungiella botschantzevii D.A.German to investigate their natural variation in salinity tolerance. Although all accessions showed survival and growth up to 700 mM NaCl in hydroponic culture, their relative salt tolerance varied considerably. All accessions accumulated the compatible solutes proline, sucrose, glucose and fructose and the polyamines putrescine and spermine. Relative salt tolerance was not correlated with the content of any of the investigated solutes. We compared the metabolomes and transcriptomes of Arabidopsis thaliana (L. Heynh.) Col-0 and E. salsugineum Yukon under control and salt stress conditions. Higher content of several metabolites in Yukon compared with Col-0 under control conditions indicated metabolic pre-adaptation to salinity in the halophyte. Most metabolic salt responses in Yukon took place at 200 mM NaCl, whereas few additional changes were observed between 200 and 500 mM. The opposite trend was observed for the transcriptome, with only little overlap between salt-regulated genes in the two species. In addition, only about half of the salt-regulated Yukon unigenes had orthologues in Col-0.
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substantial reprogramming of the eutrema salsugineum Thellungiella salsuginea transcriptome in response to uv and silver nitrate challenge
BMC Plant Biology, 2015Co-Authors: Stefanie Mucha, Dirk K Hincha, Dirk Walther, Teresa M Muller, Erich GlawischnigAbstract:Cruciferous plants synthesize a large variety of tryptophan-derived phytoalexins in response to pathogen infection, UV irradiation, or high dosages of heavy metals. The major phytoalexins of Eutrema salsugineum (Thellungiella salsuginea), which has recently been established as an extremophile model plant, are probably derivatives of indole glucosinolates, in contrast to Arabidopsis, which synthesizes characteristic camalexin from the glucosinolate precursor indole-3-acetaldoxime. The transcriptional response of E. salsugineum to UV irradiation and AgNO3 was monitored by RNAseq and microarray analysis. Most transcripts (respectively 70% and 78%) were significantly differentially regulated and a large overlap between the two treatments was observed (54% of total). While core genes of the biosynthesis of aliphatic glucosinolates were repressed, tryptophan and indole glucosinolate biosynthetic genes, as well as defence-related WRKY transcription factors, were consistently upregulated. The putative Eutrema WRKY33 ortholog was functionally tested and shown to complement camalexin deficiency in Atwrky33 mutant. In E. salsugineum, UV irradiation or heavy metal application resulted in substantial transcriptional reprogramming. Consistently induced genes of indole glucosinolate biosynthesis and modification will serve as candidate genes for the biosynthesis of Eutrema-specific phytoalexins.
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Transcriptome sequencing and microarray design for functional genomics in the extremophile Arabidopsis relative Thellungiella salsuginea (Eutrema salsugineum)
BMC Genomics, 2013Co-Authors: Yang Ping Lee, Federico M Giorgi, Marc Lohse, Kotryna Kvederaviciute, Sven Klages, Bjorn Usadel, Irute Meskiene, Richard Reinhardt, Dirk K HinchaAbstract:Background Most molecular studies of plant stress tolerance have been performed with Arabidopsis thaliana , although it is not particularly stress tolerant and may lack protective mechanisms required to survive extreme environmental conditions. Thellungiella salsuginea has attracted interest as an alternative plant model species with high tolerance of various abiotic stresses. While the T. salsuginea genome has recently been sequenced, its annotation is still incomplete and transcriptomic information is scarce. In addition, functional genomics investigations in this species are severely hampered by a lack of affordable tools for genome-wide gene expression studies. Results Here, we report the results of Thellungiella de novo transcriptome assembly and annotation based on 454 pyrosequencing and development and validation of a T. salsuginea microarray. ESTs were generated from a non-normalized and a normalized library synthesized from RNA pooled from samples covering different tissues and abiotic stress conditions. Both libraries yielded partially unique sequences, indicating their necessity to obtain comprehensive transcriptome coverage. More than 1 million sequence reads were assembled into 42,810 unigenes, approximately 50% of which could be functionally annotated. These unigenes were compared to all available Thellungiella genome sequence information. In addition, the groups of Late Embryogenesis Abundant (LEA) proteins, Mitogen Activated Protein (MAP) kinases and protein phosphatases were annotated in detail. We also predicted the target genes for 384 putative miRNAs. From the sequence information, we constructed a 44 k Agilent oligonucleotide microarray. Comparison of same-species and cross-species hybridization results showed superior performance of the newly designed array for T. salsuginea samples. The developed microarrays were used to investigate transcriptional responses of T. salsuginea and Arabidopsis during cold acclimation using the MapMan software. Conclusions This study provides the first comprehensive transcriptome information for the extremophile Arabidopsis relative T. salsuginea . The data constitute a more than three-fold increase in the number of publicly available unigene sequences and will greatly facilitate genome annotation. In addition, we have designed and validated the first genome-wide microarray for T. salsuginea , which will be commercially available. Together with the publicly available MapMan software this will become an important tool for functional genomics of plant stress tolerance.
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comparison of freezing tolerance compatible solutes and polyamines in geographically diverse collections of Thellungiella sp and arabidopsis thaliana accessions
BMC Plant Biology, 2012Co-Authors: Alexei Babakov, Bert De Boer, Ellen Zuther, Dirk K HinchaAbstract:Thellungiella has been proposed as an extremophile alternative to Arabidopsis to investigate environmental stress tolerance. However, Arabidopsis accessions show large natural variation in their freezing tolerance and here the tolerance ranges of collections of accessions in the two species were compared. Leaf freezing tolerance of 16 Thellungiella accessions was assessed with an electrolyte leakage assay before and after 14 days of cold acclimation at 4°C. Soluble sugars (glucose, fructose, sucrose, raffinose) and free polyamines (putrescine, spermidine, spermine) were quantified by HPLC, proline photometrically. The ranges in nonacclimated freezing tolerance completely overlapped between Arabidopsis and Thellungiella. After cold acclimation, some Thellungiella accessions were more freezing tolerant than any Arabidopsis accessions. Acclimated freezing tolerance was correlated with sucrose levels in both species, but raffinose accumulation was lower in Thellungiella and only correlated with freezing tolerance in Arabidopsis. The reverse was true for leaf proline contents. Polyamine levels were generally similar between the species. Only spermine content was higher in nonacclimated Thellungiella plants, but decreased during acclimation and was negatively correlated with freezing tolerance. Thellungiella is not an extremophile with regard to freezing tolerance, but some accessions significantly expand the range present in Arabidopsis. The metabolite data indicate different metabolic adaptation strategies between the species.
Hongqing Li - One of the best experts on this subject based on the ideXlab platform.
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establishment of an efficient agrobacterium tumefaciens mediated leaf disc transformation of Thellungiella halophila
Plant Cell Reports, 2007Co-Authors: Hongqing Li, Jie Xu, Lei Chen, Meiru LiAbstract:Thellungiella halophila is a salt-tolerant close relative of Arabidopsis, which is adopted as a halophytic model for stress tolerance research. We established an Agrobacterium tumefaciens-mediated transformation procedure for T. halophila. Leaf explants of T. halophila were incubated with A. tumefaciens strain EHA105 containing a binary vector pCAMBIA1301 with the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene as a reporter gene. Following co-cultivation, leaf explants were cultured on selective medium containing 10 mg l−1 hygromycin and 500 mg l−1 cefotaxime. Hygromycin-resistant calluses were induced from the leaf explants after 3 weeks. Shoot regeneration was achieved after transferring the calluses onto fresh medium of the same composition. Finally, the shoots were rooted on half strength MS basal medium supplemented with 10 mg l−1 hygromycin. Incorporation and expression of the transgenes were confirmed by PCR, Southern blot analysis and GUS histochemical assay. Using this protocol, transgenic T. halophila plants can be obtained in approximately 2 months with a high transformation frequency of 26%.
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establishment of an efficient agrobacterium tumefaciens mediated leaf disc transformation of Thellungiella halophila
Plant Cell Reports, 2007Co-Authors: Hongqing Li, Jie Xu, Lei Chen, Meiru LiAbstract:Thellungiella halophila is a salt-tolerant close relative of Arabidopsis, which is adopted as a halophytic model for stress tolerance research. We established an Agrobacterium tumefaciens-mediated transformation procedure for T. halophila. Leaf explants of T. halophila were incubated with A. tumefaciens strain EHA105 containing a binary vector pCAMBIA1301 with the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene as a reporter gene. Following co-cultivation, leaf explants were cultured on selective medium containing 10 mg l−1 hygromycin and 500 mg l−1 cefotaxime. Hygromycin-resistant calluses were induced from the leaf explants after 3 weeks. Shoot regeneration was achieved after transferring the calluses onto fresh medium of the same composition. Finally, the shoots were rooted on half strength MS basal medium supplemented with 10 mg l−1 hygromycin. Incorporation and expression of the transgenes were confirmed by PCR, Southern blot analysis and GUS histochemical assay. Using this protocol, transgenic T. halophila plants can be obtained in approximately 2 months with a high transformation frequency of 26%.
Dae-jin Yun - One of the best experts on this subject based on the ideXlab platform.
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Journal of Integrative Plant Biology 2007, 49 (10): 1484–1496 Sodium Stress in the Halophyte Thellungiella halophila and Transcriptional Changes in a thsos1-RNA Interference Line
2013Co-Authors: Qingqiu Gong, Dae-jin Yun, Ray A. Bressan, Alex Ulanov, Quan Zhang, Hans J BohnertAbstract:The plasma membrane Na + /H +-antiporter salt overly sensitive1 (SOS1) from the halophytic Arabidopsis-relative Thellungiella halophila (ThSOS1) shows conserved sequence and domain structure with the orthologous genes from Arabidopsis thaliana and other plants. When expression of ThSOS1 was reduced by RNA interference (RNAi), pronounced characteristics of salt-sensitivity were observed. We were interested in monitoring altered transcriptional responses between Thellungiella wild type and thsos1-4, a representative RNAi line with particular emphasis on root responses to salt stress at 350 mmol/L NaCl, a concentration that is only moderately stressful for mature wild type plants. Transcript profiling revealed several functional categories of genes that were differently affected in wild-type and RNAi plants. Down-regulation of SOS1 resulted in different gene expression even in the absence of stress. The pattern of gene induction in the RNAi plant under salt stress was similar to that of glycophytic Arabidopsis rather than that of wild type Thellungiella. The RNAi plants failed to down-regulate functions that are normally reduced in wild type Thellungiella upon stress and did not up-regulate functions that characterize the Thellungiella salt stress response. Metabolite changes observed in wild type Thellungiella after salt stress were less pronounced or absent in RNAi plants. Transcript and metabolite behavior suggested SOS
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role of hkt1 in Thellungiella salsuginea a model extremophile plant
Plant Signaling & Behavior, 2013Co-Authors: Akhtar Ali, Hyeong Cheol Park, Rashid Aman, Zahir Ali, Dae-jin YunAbstract:Maintenance of the cytosolic Na+/K+ ratio under saline conditions is crucial for plants. HKT-type Na+ transporters play a key role in keeping low cytosolic Na+ concentrations thus retaining a low Na+/K+ ratio, that reduces Na+ toxicity and causing high salinity stress tolerance. Two HKT-type transporters, AtHKT1 from Arabidopsis and TsHKT1;2 from Thellungiella salsuginea, that share high DNA and protein sequence identities, are distinguished by fundamentally different ion selection and salinity stress behavior. On the level of transcription, TsHKT1;2 is dramatically induced upon salt stress, whereas AtHKT1 is downregulated. TsHKT1;2-RNAi lines show severe potassium deficiency and are also sensitive to high [Na+]. We have validated the ability of the TsHKT1;2 protein to act as an efficient K+ transporter in the presence of high [Na+] by expression in yeast cells. K+ specificity is based on amino acid differences in the pore of the transporter protein relative to AtHKT1.
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the genome of the extremophile crucifer Thellungiella parvula
Nature Genetics, 2011Co-Authors: Maheshi Dassanayake, Dae-jin Yun, Ray A. Bressan, Jeffrey S Haas, Alvaro Gonzalez Hernandez, Hyewon Hong, Shahjahan AliAbstract:Dong-Ha Oh and colleagues report the draft genome of the extremophile crucifer plant Thellungiella parvula. This species is endemic to highly saline environments subject to extreme temperatures. The genome was primarily assembled using next-generation sequencing data.
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A comparative study of salt tolerance parameters in 11 wild relatives of Arabidopsis thaliana
Journal of Experimental Botany, 2010Co-Authors: Francesco Orsini, Matilde Paino D'urzo, Gunsu Inan, Dong Ha Oh, Federica Consiglio, Jae Cheol Jeong, Michael V. Mickelbart, Sara Serra, Xia Li, Dae-jin YunAbstract:Salinity is an abiotic stress that limits both yield and the expansion of agricultural crops to new areas. In the last 20 years our basic understanding of the mechanisms underlying plant tolerance and adaptation to saline environments has greatly improved owing to active development of advanced tools in molecular, genomics, and bioinformatics analyses. However, the full potential of investigative power has not been fully exploited, because the use of halophytes as model systems in plant salt tolerance research is largely neglected. The recent introduction of halophytic Arabidopsis-Relative Model Species (ARMS) has begun to compare and relate several unique genetic resources to the well-developed Arabidopsis model. In a search for candidates to begin to understand, through genetic analyses, the biological bases of salt tolerance, 11 wild relatives of Arabidopsis thaliana were compared: Barbarea verna, Capsella bursa-pastoris, Hirschfeldia incana, Lepidium densiflorum, Malcolmia triloba, Lepidium virginicum, Descurainia pinnata, Sisymbrium officinale, Thellungiella parvula, Thellungiella salsuginea (previously T. halophila), and Thlaspi arvense. Among these species, highly salt-tolerant (L. densiflorum and L. virginicum) and moderately salt-tolerant (M. triloba and H. incana) species were identified. Only T. parvula revealed a true halophytic habitus, comparable to the better studied Thellungiella salsuginea. Major differences in growth, water transport properties, and ion accumulation are observed and discussed to describe the distinctive traits and physiological responses that can now be studied genetically in salt stress research.
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sodium stress in the halophyte Thellungiella halophila and transcriptional changes in a thsos1 rna interference line
Journal of Integrative Plant Biology, 2007Co-Authors: Qingqiu Gong, Dae-jin Yun, Ray A. Bressan, Alex Ulanov, Quan Zhang, Hans J BohnertAbstract:The plasma membrane Na + /H + -antiporter salt overly sensitive1 (SOS1) from the halophytic Arabidopsis-relative Thel- lungiella halophila (ThSOS1) shows conserved sequence and domain structure with the orthologous genes from Arabidopsis thaliana and other plants. When expression of ThSOS1 was reduced by RNA interference (RNAi), pronounced characteristics of salt-sensitivity were observed. We were interested in monitoring altered transcriptional responses between Thellungiella wild type and thsos1-4, a representative RNAi line with particular emphasis on root responses to salt stress at 350 mmol/L NaCl, a concentration that is only moderately stressful for mature wild type plants. Transcript profiling revealed several functional categories of genes that were differently affected in wild-type and RNAi plants. Down-regulation of SOS1 resulted in different gene expression even in the absence of stress. The pattern of gene induction in the RNAi plant under salt stress was similar to that of glycophytic Arabidopsis rather than that of wild type Thellungiella. The RNAi plants failed to down-regulate functions that are normally reduced in wild type Thellungiella upon stress and did not up-regulate functions that characterize the Thellungiella salt stress response. Metabolite changes observed in wild type Thellungiella after salt stress were less pronounced or absent in RNAi plants. Transcript and metabolite behavior suggested SOS1 functions including but also extending its established function as a sodium transporter. The down-regulation of ThSOS1 converted the halophyte Thellungiella into a salt-sensitive plant.
