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Plant Molecular Biology 04/2013; · 4.15 Impact Factor
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ABSTRACT: Regulation of gene expression is mediated by diverse RNA binding proteins which play important roles in development and defense processes. Pumilio/FBF (Puf) protein in mammals functions as a posttranscriptional/translational repressor by binding to the 3' UTR regions of its target mRNAs. Previous study reported that APUM5 provides protection against CMV infection by directly binding to CMV RNAs in Arabidopsis. CMV RNAs contain putative Pumilio-binding motifs and APUM5 bound to the 3' UTR and some of its internal motifs both in vitro and in vivo. APUM5 works as a negative regulator of the 3' UTR of CMV and it might regulate CMV replication. Our findings suggest that APUM5 acts as a defensive repressor in plants during CMV infection. However, functions of APUM5 and other APUM members are still not clear and more studies are needed to find out the interacting partners and target mRNAs in host plant.
Plant signaling & behavior 03/2013; 8(5).
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Molecules and Cells 02/2013; 35(2):175. · 2.18 Impact Factor
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ABSTRACT: Posttranscriptional/translational regulation of gene expression is mediated by diverse RNA binding proteins and plays an important role in development and defense processes. Among the RNA-binding proteins, the mammalian Pumilio RNA-binding family (Puf) acts as posttranscriptional and translational repressors. An Arabidopsis Puf mutant, apum5-D, was isolated during a T-DNA insertional mutant screen for mutants with reduced susceptibility to Cucumber mosaic virus (CMV) infection. Interestingly, CMV RNA contained putative Pumilio-homology domain binding motifs in its 3' untranslated region (UTR) and internal places in its genome. APUM5 directly bound to the 3' UTR motifs and some internal binding motifs in CMV RNAs in vitro and in vivo. We showed that APUM5 acts as a translational repressor that regulates the 3' UTR of CMV and affects CMV replication. This study uncovered a unique defense system that Arabidopsis APUM5 specifically regulates CMV infection by the direct binding of CMV RNAs.
Proceedings of the National Academy of Sciences 12/2012; · 9.68 Impact Factor
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ABSTRACT: WRKY transcription factors regulate biotic, abiotic, and developmental processes. In terms of plant defense, WRKY factors have important roles as positive and negative regulators via transcriptional regulation or protein-protein interaction. Here, we report the characterization of the gene encoding Capsicum annuum WRKY transcription factor d (CaWRKYd) isolated from microarray analysis in the Tobacco mosaic virus (TMV)-P(0)-inoculated hot pepper plants. CaWRKYd belongs to the WRKY IIa group, a very small clade in the WRKY subfamily, and WRKY IIa group has positive/negative regulatory roles in Arabidopsis and rice. CaWRKYd transcripts were induced by various plant defense-related hormone treatments and TMV-P(0) inoculation. Silencing of CaWRKYd affected TMV-P(0)-mediated hypersensitive response (HR) cell death and accumulation of TMV-P(0) coat protein in local and systemic leaves. Furthermore, expression of some pathogenesis-related (PR) genes and HR-related genes was reduced in the CaWRKYd-silenced plants compared with TRV2 vector control plants upon TMV-P(0) inoculation. CaWRKYd was confirmed to bind to the W-box. Thus CaWRKYd is a newly identified Capsicum annuum WRKY transcription factor that appears to be involved in TMV-P(0)-mediated HR cell death by regulating downstream gene expression.
Plant Science 12/2012; 197:50-8. · 2.94 Impact Factor
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ABSTRACT: The transcription factor ATAF2, one of the plant specific NAC family genes, is known as repressor of pathogenesisrelated genes and responsive to the diverse defense-related hormones, pathogen infection, and wounding stress. Furthermore, it is important to consider that tryptophandependant IAA biosynthesis pathway can be activated by wounding and pathogen. We found that ATAF2pro::GUS reporter was induced upon indole-3-acetonitrile (IAN) treatments. And ataf2 mutant showed reduced sensitivity to IAN whereas 35S::ATAF2 plants showed hyper-sensitivity to IAN. IAN biosynthesis required nitrilase involved in the conversion of IAN to an auxin, indole-3-acetic acid (IAA). We found that the NIT2 gene was repressed in ataf2 knockout plants. Expression of both ATAF2 and NIT2 genes was induced by IAN treatment. Transgenic plants overexpressing ATAF2 showed up-regulated NIT2 expression. ATAF2 activated promoter of the NIT2 gene in Arabidopsis protoplasts. Electrophoretic mobility shift assay revealed that NIT2 promoter region from position -117 to -82 contains an ATAF2 binding site where an imperfect palindrome sequence was critical to the protein-DNA interaction. These findings indicate that ATAF2 regulates NIT2 gene expression via NIT2 promoter binding.
Molecules and Cells 09/2012; 34(3):305-13. · 2.18 Impact Factor
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ABSTRACT: The role of an expansin gene (IbEXP1) in the formation of the storage root (SR) was investigated by expression pattern analysis and characterization of IbEXP1-antisense sweetpotato (Ipomoea batatas cv. Yulmi) plants in an attempt to elucidate the molecular mechanism underlying SR development in sweetpotato. The transcript level of IbEXP1 was high in the fibrous root (FR) and petiole at the FR stage, but decreased significantly at the young storage root (YSR) stage. IbEXP1-antisense plants cultured in vitro produced FRs which were both thicker and shorter than those of wild-type (WT) plants. Elongation growth of the epidermal cells was significantly reduced, and metaxylem and cambium cell proliferation was markedly enhanced in the FRs of IbEXP1-antisense plants, resulting in an earlier thickening growth in these plants relative to WT plants. There was a marked reduction in the lignification of the central stele of the FRs of the IbEXP1-antisense plants, suggesting that the FRs of the mutant plants possessed a higher potential than those of WT plants to develop into SRs. IbEXP1-antisense plants cultured in soil produced a larger number of SRs and, consequently, total SR weight per IbEXP1-antisense plant was greater than that per WT plant. These results demonstrate that SR development was accelerated in IbEXP1-antisense plants and suggest that IbEXP1 plays a negative role in the formation of SR by suppressing the proliferation of metaxylem and cambium cells to inhibit the initial thickening growth of SRs. IbEXP1 is the first sweetpotato gene whose role in SR development has been directly identified in soil-grown transgenic sweetpotato plants.
Journal of Experimental Botany 09/2012; · 5.36 Impact Factor
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ABSTRACT: Tsip1, a Zn finger protein that was isolated as a direct interactor with tobacco stress-induced 1 (Tsi1), plays an important role in both biotic and abiotic stress signaling. To further understand Tsip1 function, we searched for more Tsip1-interacting proteins by yeast two-hybrid screening using a tobacco cDNA library. Screening identified a new Tsip1-interacting protein, Nicotiana tabacum Tsip1-interacting ferredoxin 1 (NtTfd1), and binding specificity was confirmed both in vitro and in vivo. The four repeats of a cysteine-rich motif (CXXCXGXG) of Tsip1 proved important for binding to NtTfd1. Virus-induced gene silencing of NtTfd1, Tsip1, and NtTfd1/Tsip1 rendered plants more susceptible to salinity stress compared with TRV2 control plants. NtTfd1- and Tsip1-silenced tobacco plants were more susceptible to infection by Cucumber mosaic virus compared with control plants. These results suggest that NtTfd1 might be involved in the regulation of biotic and abiotic stresses in chloroplasts by interaction with Tsip1.
Molecules and Cells 06/2012; 34(1):43-52. · 2.18 Impact Factor
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ABSTRACT: We have identified a cDNA clone(CaEF1A) sharing significant homology with the protein synthesis elongation factor 1As (eEFIA) found in eukaryotes. This clone was
isolated from a tobacco mosaic virus (TMV)-inoculatecl hot pepper(Capsicum annuum L.) cDNA library by differential screening. Based on the results of our Southern blot analysis using theCaEFIA full-length cDNA clone as a probe, we suggest thatCaEFIA exists as part of a multigene family in ~e hot pepper genome. In another experiment, the mRNA of theCaEFIA gene was found to accumulate in ripe fruits, flowers, young and old leaves, and roots, but was not detected in immature fruits
or stems. The transcript ofCaEFIA accumula-tion was induced within 12 h of local wounding treatment, as well as by both avirulent and virulent TMV inoculations.
Journal of Plant Biology 04/2012; 44(4):199-204. · 1.07 Impact Factor
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ABSTRACT: Programmed cell death (PCD) in plant cells is often accompanied by biochemical and morphological hallmarks similar to those
of animal apoptosis. However, orthologs of several core components of such apoptosis have not been reported in plants. Here,
we describe an ortholog of Fas-associated factor1 (FAF1), a member of the Fas-death-inducing signaling complex (Fas-DISC),
found in pepper. We also examined FAF1 orthologs in other plant species. Transcripts of CaFAF1 specifically accumulated in pepper leaves infected with the avirulent pepper mild mottle virus (PMMoV) P0 pathotype. This gene was also strongly expressed in aging leaves. To determine whether those orthologs are involved in PCD,
we suppressed their expression through virus-induced gene silencing, and determined the effect on the hypersensitive response
(HR), a typical PCD, in pepper, tomato, and tobacco. Constitutive expression of CaFAF1 in transgenic tobacco triggered spontaneous
induction of cell death lesions and induced pathogenesis-related (PR) genes. This ability to cause cell death and suppress R gene-mediated HR in its knockdown condition suggests that some features of animal and plant cell death processes may be shared.
We propose that plant FAF1 is a conserved cell death regulator in both kingdoms.
Journal of Plant Biology 04/2012; 52(2):125-134. · 1.07 Impact Factor
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ABSTRACT: Hypersensitive response (HR) cell death upon plant virus infection is an excellent plant strategy for inhibiting viral movement and obtaining systemic acquired resistance (SAR) against further infection. Various host factors are involved in these HR processes, either directly as viral resistance proteins or indirectly. We characterized a gene encoding the CaBtf3 [β-nascent polypeptide-associated complex (NAC) subunit] of NAC from the hot pepper plant. NAC contacts nascent polypeptides to prevent aggregation and degradation of newly synthesized proteins by controlling cotranslational protein folding. CaBtf3 protein fused to green fluorescent protein predominantly localized to the nucleus. Silencing phenotype of CaBtf3 upon the Tobacco mosaic virus (TMV)-P(0) inoculation exhibited reduced HR cell death and decreased expression of some HR-associated genes, but increased TMV coat protein levels compared with TRV2 control plants. Furthermore, silencing of NbBtf3, a highly homologous gene of CaBtf3, also led to the reduced Bax- and Pto-mediated cell death. The results indicate that CaBtf3 might be involved in HR cell death and could function as a transcription factor in the nucleus by transcriptional regulation of HR-related gene expression.
Biochemical and Biophysical Research Communications 12/2011; 417(2):910-7. · 2.48 Impact Factor
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ABSTRACT: In plant, some WRKY transcription factors are known to play an important role in the transcriptional reprogramming associated with the immune response. By using WRKY-domain-specific differential display procedure, we isolated CaWRKYb gene, which is rapidly induced during an incompatible interaction between hot pepper and Tobacco mosaic virus (TMV) pathotype P(0) infection. The recombinant CaWRKYb bound to the W box-containing CaPR-10 promoter probes efficiently and the specificity of binding was confirmed by mutant study and competition with cold oligonucleotides. Also, in GUS reporter activity assay using Arabidopsis protoplasts with the CaPR-10 promoter, GUS activity was increased in the presence of CaWRKYb. And CaWRKYb-knockdown plant showed reduced number of hypersensitive response local lesions upon TMV-P(0) infection. Furthermore, CaWRKYb-knockdown plant exhibited compromised resistance to TMV-P(0) by accumulating more TMV, apparently through decreased expression of CaPR-10, CaPR-1, and CaPR-5. These results suggest that CaWRKYb is involved as a positive transcription factor in defense-related signal transduction pathways in hot pepper.
Biochemical and Biophysical Research Communications 08/2011; 411(3):613-9. · 2.48 Impact Factor
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ABSTRACT: Harvestable, starch-storing organs of plants, such as fleshy taproots and tubers, are important agronomic products that are also suitable target organs for use in the molecular farming of recombinant proteins due to their strong sink strength. To exploit a promoter directing strong expression restricted to these storage organs, we isolated the promoter region (3.0 kb) of SRD1 from sweetpotato (Ipomoea batatas cv. 'White Star') and characterized its activity in transgenic Arabidopsis, carrot, and potato using the β-glucuronidase (GUS) gene (uidA) as a reporter gene. The SRD1 promoter conferred root-specific expression in transgenic Arabidopsis, with SRD1 promoter activity increasing in response to exogenous IAA. A time-course study of the effect of IAA (50 μM) revealed a maximum increase in SRD1 promoter activity at 24 h post-treatment initiation. A serial 5' deletion analysis of the SRD1 promoter identified regions related to IAA-inducible expression as well as regions containing positive and negative elements, respectively, controlling the expression level. In transgenic carrot, the SRD1 promoter mediated strong taproot-specific expression, as evidenced by GUS staining being strong in almost the entire taproot, including secondary phloem, secondary xylem and vascular cambium. The activity of the SRD1 promoter gradually increased with increasing diameter of the taproot in the transgenic carrot and was 10.71-fold higher than that of the CaMV35S promoter. The SRD1 promoter also directed strong tuber-specific expression in transgenic potato. Taken together, these results demonstrate that the SRD1 promoter directs strong expression restricted to the underground storage organs, such as fleshy taproots and tubers, as well as fibrous root tissues.
Transgenic Research 06/2011; 21(2):265-78. · 2.75 Impact Factor
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ABSTRACT: • In Cucumber mosaic virus (CMV) RNA replication, replicase-associated protein CMV 1a and RNA-dependent RNA polymerase protein CMV 2a are essential for formation of an active virus replicase complex on vacuolar membranes. • To identify plant host factors involved in CMV replication, a yeast two-hybrid system was used with CMV 1a protein as bait. One of the candidate genes encoded Tsi1-interacting protein 1 (Tsip1), a zinc (Zn) finger protein. Tsip1 strongly interacted with CMV 2a protein, too. • Formation of a Tsip1 complex involving CMV 1a or CMV 2a was confirmed in vitro and in planta. When 35S::Tsip1 tobacco (Nicotiana tabacum) plants were inoculated with CMV-Kor, disease symptom development was delayed and the accumulation of CMV RNAs and coat protein was decreased in both the infected local leaves and the uninfected upper leaves, compared with the wild type, whereas Tsip1-RNAi plants showed modestly but consistently increased CMV susceptibility. In a CMV replication assay, CMV RNA concentrations were reduced in the 35S::Tsip1 transgenic protoplasts compared with wild-type (WT) protoplasts. • These results indicate that Tsip1 might directly control CMV multiplication in tobacco plants by formation of a complex with CMV 1a and CMV 2a.
New Phytologist 04/2011; 191(3):746-62. · 6.64 Impact Factor
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ABSTRACT: Cytokinins affect plant immunity to various pathogens; however, the mechanisms coupling plant-derived cytokinins to pathogen responses have been elusive. Here, we found that plant-derived cytokinins promote resistance of Arabidopsis to Pseudomonas syringae pv. tomato DC3000 (Pst). Modulated cytokinin levels or signaling activity in CKX- or IPT-overexpressing plants or in ahk2 ahk3 mutants correlated with altered resistance. In fact, the cytokinin-activated transcription factor ARR2 contributes specifically to Pst resistance. The salicylic acid (SA) response factor TGA3 binds ARR2, and mutation of TGA-binding cis-elements in the Pr1 promoter abolished cytokinin- and ARR2-dependent Pr1 activation. Cytokinin treatment did not increase pathogen resistance in tga3 plants, as the cytokinin-dependent induction of Pr1 was eliminated. Moreover, SA signaling enhanced binding of ARR2/TGA3 to the Pr1 promoter. Taken together, these results show that cytokinins modulate the SA signaling to augment resistance against Pst, a process in which the interaction between TGA3 and ARR2 is important.
Developmental cell 08/2010; 19(2):284-95. · 13.36 Impact Factor
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ABSTRACT: A sweetpotato (Ipomoea batatas cv. 'Jinhongmi') MADS-box protein cDNA (SRD1) has been isolated from an early stage storage root cDNA library. The role of the SRD1 gene in the formation of the storage root in sweetpotato was investigated by an expression pattern analysis and characterization of SRD1-overexpressing (ox) transgenic sweetpotato plants. Transcripts of SRD1 were detected only in root tissues, with the fibrous root having low levels of the transcript and the young storage root showing relatively higher transcript levels. SRD1 mRNA was mainly found in the actively dividing cells, including the vascular and cambium cells of the young storage root. The transcript level of SRD1 in the fibrous roots increased in response to 1000 muM indole-3-acetic acid (IAA) applied exogenously. During the early stage of storage root development, the endogenous IAA content and SRD1 transcript level increased concomitantly, suggesting an involvement of SRD1 during the early stage of the auxin-dependent development of the storage root. SRD1-ox sweetpotato plants cultured in vitro produced thicker and shorter fibrous roots than wild-type plants. The metaxylem and cambium cells of the fibrous roots of SRD1-ox plants showed markedly enhanced proliferation, resulting in the fibrous roots of these plants showing an earlier thickening growth than those of wild-type plants. Taken together, these results demonstrate that SRD1 plays a role in the formation of storage roots by activating the proliferation of cambium and metaxylem cells to induce the initial thickening growth of storage roots in an auxin-dependent manner.
Journal of Experimental Botany 02/2010; 61(5):1337-49. · 5.36 Impact Factor
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ABSTRACT: Capsicum annuum L. Bugang exhibits a hypersensitive response against Tobacco mosaic virus (TMV) P(0) infection. The C. annuumUDP-glucosyltransferase 1 (CaUGT1) gene was upregulated during resistance response to TMV and by salicylic acid, ethephon, methyl viologen, and sodium nitroprusside treatment. When the gene was downregulated by virus-induced gene silencing, a delayed HR was observed. In addition, free and total SA concentrations in the CaUGT1-downregulated hot pepper were decreased by 52% and 48% compared to that of the control plants, respectively. This suggested that the CaUGT1 gene was involved in resistance response against TMV infection by controlling the accumulation of SA.
FEBS letters 07/2009; 583(13):2315-20. · 3.54 Impact Factor
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ABSTRACT: The FCA protein is involved in controlling flowering time and plays more general roles in RNA-mediated chromatin silencing in Arabidopsis. It contains two RNA-binding domains and a WW domain. The FCA protein interacts with FY, a polyadenylation factor, via its WW domain. We previously characterized a rice gene, OsFCA, which was homologous to FCA. Here, we found that the OsFCA protein could interact through its WW domain with the following proteins: OsFY, a protein containing a CID domain present in RNA-processing factors such as Pcf11 and Nrd1; a protein similar to splicing factor SF1; a protein similar to FUSE splicing factor; and OsMADS8. The FY protein is associated with the 3' end processing machinery in Arabidopsis. Thus, we examined interactions between OsFY and the rice homologs (OsCstF-50, -64 and -77) of the AtCstF-50, -64 and -77 proteins. We found that OsFY could bind OsCstF50, whereas the OsCstF77 protein could bridge the interaction between OsCstF50 and OsCstF64. Taken together, our data suggest that OsFCA could interact with several proteins other than OsFY through its WW domain and may play several roles in rice.
Plant and Cell Physiology 07/2009; 50(8):1479-92. · 4.70 Impact Factor
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ABSTRACT: We report here a first evaluation of chilling-responsive gene regulation in the sweetpotato. The growth of sweetpotato plants
was severely retarded at 12°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°C). In the leaf and petiole, the highest transcript levels
were those of IbEXP1 at 28°C, whereas IbEXPL1 transcript levels were highest in the root. IbEXP1 mRNA levels in the 12°C-treated petiole showed a fluctuating pattern (transient decrease–recovery–stable decrease) for 48h.
In the leaf and petiole, IbEXP1 and IbEXPL1 exhibited a similar response to chilling in that their mRNA levels decreased at 22°C, increased at 16°C, and decreased dramatically
at 12°C. In contrast, mRNA levels of IbEXP2 in the leaf fell gradually as the temperature fell from 28 to 12°C, while they remained unaltered in the petiole. In the
root, mRNA levels of IbEXPL1 and IbEXP1 reached maximum levels at 16°C, and decreased significantly at 12°C. These data demonstrated that expression of these three
expansin genes was ultimately down-regulated at 12°C; however, transcriptional regulation of each expansin gene exhibited
its own distinctive pattern in response to various chilling temperatures.
Plant Biotechnology Reports 01/2009; 3(1):75-85. · 1.19 Impact Factor
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ABSTRACT: A full length cDNA clone encoding Capsicum annuum GDSL-lipase 1 (CaGL1) was isolated by microarray analysis. The expression of CaGL1 was triggered by methyl jasmonic acid (MeJA), an important signal in abiotic/biotic stress response. However, the expression of this gene was not increased by the application of salicylic acid (SA) or ethylene treatment. And, local/systemic wounding stimuli resulted in rapid accumulation of CaGL1 mRNA. However, CaGL1 was not specifically induced during the hypersensitive response upon Tobacco mosaic virus (TMV) inoculation. By using a virus-induced gene silencing (VIGS)-based reverse genetic approach, it was observed that the suppression of CaGL1 attenuates the expression of Capsicum annuumpathogenesis-related protein 4 (CaPR-4) during wound stress. However, the CaPR-4 transcript level induced by TMV was not regulated by CaGL1 expression. These results indicate that CaGL1 may be involved in signaling pathway of MeJA and/or the wound responses through CaPR-4 expression modulation.
Biochemical and Biophysical Research Communications 11/2008; 374(4):693-8. · 2.48 Impact Factor
