• Journal of Life Science
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• v.23 no.2
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• pp.182-189
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• 2013

Halophytes are unique land plants that are capable of thriving in a high-salt environment. They are attracting public attention due to their ability to synthesize bioactive substances such as UV protectants or antioxidizing agents. To achieve unaffected growth under high salinity, halophytes may take advantage of the activities of cell growth factors such as expansins. Expansins are well-known cell wall proteins that are responsible for cell enlargement. They loosen cell walls, thereby contributing to actual plant growth. This study aimed to identify positive roles of expansins in the growth of halophytes. Three expansin cDNA clones were isolated from seedlings of Suaeda japonica. Comparing the deduced amino acid sequences of the expansin genes of S. japonica with those of other plant species suggested that the cDNA clones isolated from S. japonica belong to the EXPA (${\alpha}$-expansin) gene family. A phylogenetic tree based on the deduced amino acid sequences revealed that the expansins of S. japonica share a close evolutionary relationship with those of strawberry (Fragaria ananassa) and jujube (Ziziphus jujuba), both of which are woody dicots. SjEXPAs did not show any remarkable change in the gene expression level in different NaCl concentrations, providing a clue to the unaffected seedling growth of S. japonica in a high-salt environment. In conclusion, the present study presents the first report of expansin genes from halophytes and suggests a putative role for these genes in plant growth under high salinity.

• Journal of the Korean Society of Tobacco Science
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• v.27 no.2
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• pp.153-162
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• 2005

Tobacco (Nicotiana tabacum L.) cells were transformed with rice expansin genes, OsEXPA4, OsEXPB3, OsEXPB4, and OsEXPB6, to elucidate the function of the genes in tobacco cells. The transformation increased the mass of the callus by $36\%-65 \%$, and the cell length by $12\%-28\%$. The cell width was decreased by $3\%$ for OsEXPB3, not changed for OsEXPB4, increased by $25\%\;and\;20\%$ for OsEXPA4 and OsEXPB6, respectively. From database search, seven expansin genes were found and six of them belong to EXPA group and one of them belongs to EXPB group. EXLA and EXLB were not found. All tobacco expansin genes were evenly distributed in the phylogenetic tree of rice and Arabidopsis expansin genes.

• The Plant Pathology Journal
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• v.20 no.1
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• pp.18-21
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• 2004

The root hair provides a major entering spot for the symbiotic legume rhizobia. It is obvious that dynamic cell wall modification occurs in the plant root hair during the early microbe invasion. Expansins are nondestructive cell wall-modifying proteins that are involved in cell growth and differentiation. Among about 40 expansin genes in Arabidopsis, two expansin genes are expressed specifically in the root hair cell. Orthologous genes of this Arabidopsis root hair expansins have been found in other Brassica members, rice, and Medicago truncatula (a legume). In this review, I discuss the probable function of expansins during the early symbiotic process between the root hair and microbes and the regulation of root hair expansin genes in a comparative approach.

• Plant Biotechnology Reports
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• v.3 no.1
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• pp.75-85
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• 2009

We report here a first evaluation of chilling-responsive gene regulation in the sweetpotato. The growth of sweetpotato plants was severely retarded at $12^{\circ}C$; the lengths of the leaf, petiole, and root were markedly reduced and microscopic observation revealed that the elongation growth of the epidermal cells in each of these organs was significantly reduced. We examined the transcriptional regulation of three sweetpotato expansin genes (IbEXP1, IbEXP2 and IbEXPL1) in response to various chilling temperatures (12, 16, 22, and $28^{\circ}C$). In the leaf and petiole, the highest transcript levels were those of IbEXP1 at $28^{\circ}C$, whereas IbEXPL1 transcript levels were highest in the root. IbEXP1 mRNA levels in the $12^{\circ}C-treated$ petiole showed a fluctuating pattern (transient decrease-recovery-stable decrease) for 48 h. In the leaf and petiole, IbEXP1 and IbEXPL1 exhibited a similar response to chilling in that their mRNA levels decreased at $22^{\circ}C$, increased at $16^{\circ}C$, and decreased dramatically at $12^{\circ}C$. In contrast, mRNA levels of IbEXP2 in the leaf fell gradually as the temperature fell from 28 to $12^{\circ}C$, while they remained unaltered in the petiole. In the root, mRNA levels of IbEXPL1 and IbEXP1 reached maximum levels at $16^{\circ}C$, and decreased significantly at $12^{\circ}C$. These data demonstrated that expression of these three expansin genes was ultimately down-regulated at $12^{\circ}C$; however, transcriptional regulation of each expansin gene exhibited its own distinctive pattern in response to various chilling temperatures.

• Journal of Microbiology and Biotechnology
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• v.28 no.4
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• pp.622-629
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• 2018

Expansins are cell wall proteins that mediate cell wall loosening and promote specific tissue and organ morphogenesis in plants and in some microorganisms. Unlike plant expansins, the biological functions of fungal expansin-like proteins have rarely been discussed. In the present study, an expansin-like protein-encoding fvexpl1 gene, was identified from Flammulina velutipes by using local BLAST. It consisted of five exons with a total length of 822 bp. The deduced protein FVEXPL1 contained 274 amino acids with a predicted molecular mass and isoelectric point of 28,589 Da and pH 4.93, respectively. The first 19 amino acids from the N terminal are the signal peptide. Phylogenetic analysis and multiple protein alignment indicated FVEXPL1 was an expansin-like protein. The expression level of fvexpl1 gene in the stipe was significantly higher than that in the mycelia, primordia, and cap. However, the expression level of fvexpl1 gene was significantly higher in the fast elongation region of the stipe as compared with the slow elongation region. Expression analysis indicated that fvexpl1 gene might have an auxiliary role in the stipe morphogenesis of F. velutipes.

• Molecules and Cells
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• v.20 no.1
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• pp.119-126
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• 2005

${\alpha}$-Expansins are bound to the cell wall of plants and can be solubilized with an extraction buffer containing 1 M NaCl. Localization of ${\alpha}$-expansins in the cell wall was confirmed by immunogold labeling and electron microscopy. The subcellular localization of vegetative ${\beta}$-expansins has not yet been studied. Using antibodies specific for OsEXPB3, a vegetative ${\beta}$-expansin of rice (Oryza sativa L.), we found that OsEXPB3 is tightly bound to the cell wall and, unlike ${\alpha}$-expansins, cannot be solubilized with extraction buffer containing 1 M NaCl. OsEXPB3 protein could only be extracted with buffer containing SDS. The subcellular localization of the OsEXPB3 protein was confirmed by immunogold labeling and electron microscopy. Gold particles were mainly distributed over the primary cell walls. Immunohistochemistry showed that OsEXPB3 is present in all regions of the coleoptile and root tissues tested.

• 한국약용작물학회:학술대회논문집
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• 2011.09a
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• pp.206-207
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• 2011

• KOGO NEWS
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• v.5 no.3
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• pp.13-18
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• 2005

• Proceedings of the Korean Society of Tobacco Science Conference
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• 2005.10a
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• pp.40-40
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• 2005

• Journal of Applied Biological Chemistry
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• v.49 no.4
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• pp.148-153
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• 2006

While the underlying molecular mechanism remains to be elucidated, recent studies suggest that polar auxin transport is a key controlling factor in triggering differential growth responses to gravity. Identification of regulatory components in auxin-mediated differential cell expansion would improve our understanding of the gravitropic response. In this study, we identify a mutant designated aux1-like(later changed to aux1), an allele of the aux1 mutant that exhibits a severely disrupted root gravitropic response, but no defects in developmental processes. In Arabidopsis, AUX1 encodes an auxin influx carrier. Since in-depth characterization of the gravitropic response caused by mutations in this gene has been performed previously, we focused on identifying the downstream genes that were differentially expressed compared to wild-type plants. Consistent with the mutant phenotype, the transcription of the auxin-responsive genes IAA17 and GH3 were altered in aux1 plants treated with IAA, 2, 4-D and NAA. In addition, we identified two expansin genes EXP10 and EXPL3 that exhibited different expression in wild-type and mutant plants.