Os07g0186000

As a subgroup I h-type Trx in rice, OsTRXh1 regulates the redox state of the apoplast and influences plant development and stress responses.

Annotated Information

Function

OsTRXh1 could be secreted into the rice apoplast by transient expression and immunohistochemistry experiments. Furthermore, in the apoplast of rice, OsTRXh1 was induced by salt stress at the protein level. It has a conserved redox-active site (WCGPC), which involves in the redox status regulation of target proteins. OsTRXh1 not only had the ability to reduce insulin in the presence of DTT but also it can complement the hydrogen peroxide sensitivity of the thioredoxin-deficient yeast mutant. OsTRXh1 possesses disulfide reductase activity and could be secreted into the extracellular regions. The knockdown and overexpression transgenic plants in rice showed that it involved in salt and ABA response regulation. More hydrogen peroxide was produced in the extracellular space of OsTRXh1 knockdown plants than in wild-type plants under salt stress, whereas the OsTRXh1 overexpression plants produced less hydrogen peroxide under the same conditions,which suggesting that OsTRXh1 regulated apoplastic ROS accumulation and influenced plant stress responses in rice. Recently, a report showed that OsTRXh1 was induced by cold stress and negatively regulated the kinase activities of Oryza sativa Mitogen-activated Protein Kinase3 (OsMPK3) and OsMPK6 in vitro through a redox-dependent mechanism.

GO assignment(s): GO:0005489, GO:0006118

Mutation

Figure 1.The growth performance of the transformed yeast mutant EMY63 under synthetic dextrose/Gal/-Ura agar medium containing 0 mM H₂O₂ and 0.7 mM H₂O₂.(from reference ).

To test whether OsTRXh1 has the ability to complement the yeast mutant, the full-length cDNA of OsTRXh1 and the OsTRXh1^C43S mutant were introduced into the yeast mutant.The yeast mutant cells expressing the wild type OsTRXh1 grew as well as the positive control, whereas the transformants expressing the OsTRXh1^C43S mutant did not grow in the culture medium containing H₂O₂ (Figure 1). All transformed yeast mutant cells grew well in medium that did not contain H₂O₂. These results indicate that OsTRXh1 had the ability to complement the H₂O₂ hypersensitivity of the trx1△ trx2△ yeast mutant but the OsTRXh1^C43S mutant did not.

Expression

Figure 2.Expression pattern of OsTRXh1.(from reference )

• OsTRXh1 is a salt and abscisic acid response gene and is extensively expressed:

The OsTRXh1 mRNA expression levels were slightly increased after treatment with 100 mM NaCl for 3 h, and a nearly 2.2-fold increase was observed after treatment for 6 h (Fig. 2A). We also found that OsTRXh1 expression was slightly induced by abscisic acid (ABA; Fig. 2B). The expression level of its homologous gene, OsTRXh2, was lower as compared with OsTRXh1 in whole plants under the same conditions(Fig. 2, A and B). The expression analysis of OsTRXh1 under normal conditions using RT-PCR showed that OsTRXh1 was expressed in all of the tissues examined, and the level of transcription was abundant in leaves and nodes(Fig. 5C).During seed germination, GUS staining was detected at the radicle, germ (Fig. 2, D and E), bud, and root of 5-d-old seedlings (Fig. 2F). In seedlings, OsTRXh1 was expressed in the leaf, root, and shoot apical meristem (Fig. 2, G–I). In mature rice plants, staining was detected in the stem and node (Fig.2, J and K). We could also detect OsTRXh1 expression in the palea, lodicule, stamen, pistil, and panicle during the reproductive phase (Fig. 2, L and M). OsTRXh1 expression was also observed in the callus (Fig. 2N), indicating that OsTRXh1 is a stress-responsive gene that is widely expressed in rice.

• Knockdown of OsTRXh1 in Rice Causes dwarf and low-tillering Phenotypes: after the formation of the fourth complete leaf, the OsTRXh1 RNAi lines showed a dwarf phenotype as compared with wild-type plants. In 60-d-old OsTRXh1 RNAi plants, the knockdown of OsTRXh1 led to the dwarf and low-tillering phenotypes in the late developmental stages, and the knockdown of OsTRXh1 increases H₂O₂ levels.
• Knockdown or Overexpression of OsTRXh1 Leads to an ABA-Insensitive Phenotype: the ABA pathway was impaired in the OsTRXh1 overexpression and RNAi lines.
• OsTRXh1 is expressed extensively and is involved in salt and ABA Responses by regulating the apoplastic ROS Accumulation plant growth and development

Subcellular localization

To determine the subcellular localization of OsTRXh1, fluorescently tagged OsTRXh1-YFP (for yellow fluorescent protein) and YFP-OsTRXh1 fusion proteins were transiently expressed in onion (Allium cepa) epidermal cells by particle bombardment. The fluorescence of OsTRXh1-GFP could be detected in the cell wall region, whereas the GFP control was distributed in the intracellular region and could not be detected in the extracellular region. OsTRXh1 is secreted into extracellular regions.

Evolution

Figure 3.Phylogenetic tree of rice and Arabidopsis h-type Trxs and an N. alata-secreted Trx.(from reference )

Figure 4.A schematic cell illustrating locations of different components from NTS based on the following references(from reference )

• A phylogenetic tree was constructed with rice and Arabidopsis h-type Trxs and an N. alata-secreted Trx. OsTRXh1, together with OsTRXh2, OsTRXh3, OsTRXh6, AtTRXh1, AtTRXh3, AtTRXh4, and AtTRXh5, belongs to the h-type Trx subgroup I (Figure 3). The amino acid sequence alignment of OsTRXh1, OsTRXh2, AtTRXh1, AtTRXh3, AtTRXh4, AtTRXh5, and NaTrxh shows that OsTRXh1 has the common structure of Trxs and a conserved redox-active site.
• Although h-type Trxs are considered to be mainly cytosolic, some Trx-h are apparently translocated to other compartments(Fig. 4).

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References

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Structured Information

Gene Name	Os07g0186000
Description	Similar to Thioredoxin h isoform 1
Version	NM_001065604.1 GI:115470940 GeneID:4342593
Length	1911 bp
Definition	Oryza sativa Japonica Group Os07g0186000, complete gene.
Source	Oryza sativa Japonica Group ORGANISM Oryza sativa Japonica Group Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta; Spermatophyta; Magnoliophyta; Liliopsida; Poales; Poaceae; BEP clade; Ehrhartoideae; Oryzeae; Oryza.
Chromosome	Chromosome 7
Location	Chromosome 7:4606471..4608381
Sequence Coding Region	4606739..4606894,4606976..4607098,4608199..4608288
Expression	GEO Profiles:Os07g0186000
Genome Context	<gbrowseImage1> name=NC_008400:4606471..4608381 source=RiceChromosome07 preset=GeneLocation </gbrowseImage1>
Gene Structure	<gbrowseImage2> name=NC_008400:4606471..4608381 source=RiceChromosome07 preset=GeneLocation </gbrowseImage2>
Coding Sequence	<cdnaseq>atggccgccgaggagggagtcgtgatcgcctgccacaacaaggacgagttcgacgcccagatgaccaaggccaaggaggccggcaaagtggtcataattgacttcactgcttcctggtgtggcccttgccgcttcatcgccccagtgttcgctgaatacgccaaaaagttccctggtgctgtcttcctgaaggttgatgttgatgagctgaaggaagttgctgaaaagtacaatgtcgaggcaatgccgaccttcctattcatcaaggatggtgctgaggctgacaaggtcgttggcgccaggaaggatgacctccagaacaccatcgtgaagcacgtcggtgccactgctgcatctgcttctgcctaa</cdnaseq>
Protein Sequence	<aaseq>MAAEEGVVIACHNKDEFDAQMTKAKEAGKVVIIDFTASWCGPCR FIAPVFAEYAKKFPGAVFLKVDVDELKEVAEKYNVEAMPTFLFIKDGAEADKVVGARK DDLQNTIVKHVGATAASASA</aaseq>
Gene Sequence	<dnaseqindica>1488..1643#1284..1406#94..183#gcaatctcatcgcaagaaaagaaaaaaaatcctattcaaatcgaaacccctctctttgatctcgtcgccgaggaattaggaggagagagagcaatggccgccgaggagggagtcgtgatcgcctgccacaacaaggacgagttcgacgcccagatgaccaaggccaaggaggccggcaaagtggtaagtttcctggcgcagaattttggggatttttttttgggggttttgttcaccagggggtcgcggttcgtcttagatcgataggattttgaagaaatttaggatttaatttcttgctgagatttgtggcatgtggtgaaatcgcgaggagatcgattgtttctattttggcgattggggcgtagggttgtcgcggatttggggattgccgattctggtgggggagattttagtagtagattttcatgaatatattttaggatgatataatgaacaattcttttaaaagaaatctgttgcagtaattacagggcactctgtatttgacatgattaatcgttgatgtttggattttaccatgagatggggcgatttgatgcttacatctgcaagcgaattttcatccgctatctgtatagtatttgactccataggcgaaattgttagtgtttaaatttaccgtaagatgggatggtgtgatgtgatgtttaggtttgctccagttgtttcatgctgatgattctctaatttgagtataagctttgtttaaatatatagatatattcttaaatagtactataatttgacatgattcgccagagttgaaggaaatctggttctaatctagttcaattgttgttatggacaatagattgccacttcacatgtcttggcattgttatgatgtgatgctttgtacagataagcgtccgccctgtagtattggatttggtttcttgctgcgcggcataaacgaggattttgaccaagagtattatatttgaactgtattagatttggtttcttgctgtgcggcatcaacgaggattttgatcaagagtagttagcacttaccaggctgatatattgttgtctatggaattatcaatggttcttggatttattttctttctgtgcaacaacaacaaggttgccaaagaatatttatctagtatgaaattctgaactagtggtacttatgcttgtcatgccaataactgtgaggctaccgttattctttcttactgcgcaattgaccatttgttcatgtcatgtttccatccctaatgatggccttttctggactgtttgatctacaggtcataattgacttcactgcttcctggtgtggcccttgccgcttcatcgccccagtgttcgctgaatacgccaaaaagttccctggtgctgtcttcctgaaggttgatgttgatgagctgaaggtgcgcagagttgcccacaatcttccaaaaacatttttgtcacccctgtgatagtgagtaatgcttttctttatccaacaggaagttgctgaaaagtacaatgtcgaggcaatgccgaccttcctattcatcaaggatggtgctgaggctgacaaggtcgttggcgccaggaaggatgacctccagaacaccatcgtgaagcacgtcggtgccactgctgcatctgcttctgcctaagaattctcgcaggcgcaagttatcaaataagggccagcacctggtgttgtagtaggtattagcgttagtcatcgttatcgtcagtttggcttgggtgtcctcgaatatcatgcgaaatcgattccgagttctctttttaaaattcctgatgatgatatatagtttgtggaaatttggatctggctattctgtacgagtttgctgactattaaagcaattattataatatgatgatgctggcaagcttgtagatagcttgaatttgtcc</dnaseqindica>
External Link(s)	NCBI Gene:Os07g0186000, RefSeq:Os07g0186000