February 2009, Volume 51 Issue 2, Pages 113223.


Cover Caption:
AtANK1 on ER of Arabidopsis
Many ankyrin-repeat proteins are present in plant cells, but the knowledge about their function and subcellular distribution is often minimal. A gene named AtANK1 encoding an ankyrin-like protein was cloned from Arabidopsis, and the derived protein was found on the membrane of the endoplasmic reticulum (ER) in Arabidopsis. See pages 140C146 for details (cover design: Ying Wang).

 

          Cell and Developmental Biology
Arabidopsis profilin isoforms, PRF1 and PRF2 show distinctive binding activities and subcellular distributions ties  
Author: Feng Wang, Yanping Jing, Zhen Wang, Tonglin Mao, Jozef Šamaj, Ming Yuan and Haiyun Ren
Journal of Integrative Plant Biology 2009 51(2): 113-121
DOI: 10.1111/j.1744-7909.2008.00781.x
      
    Profilin is an actin-binding protein that shows complex effects on the dynamics of the actin cytoskeleton. There are five profilin isoforms in Arabidopsis thaliana. However, it is still an open question whether these isoforms are functionally different. In present study, two profilin isoforms from Arabidopsis, PRF1 and PRF2 were fused with GFP tag and expressed in E. coli and Arabidopsis thaliana in order to compare their biochemical properties in vitro and their cellular distributions in vivo. Biochemical analysis revealed that fusion proteins of GFP-PRF1 and GFP-PRF2 can bind to poly-L-proline and G-actin showing remarkable differences. GFP-PRF1 has much higher affinities for both poly-L-proline and G-actin comparing to GFP-PRF2. Observations of living cells in stable transgenic Arabidopsis thaliana lines revealed that 35S::GFP-PRF1 formed a filamentous network, while 35S::GFP-PRF2 formed polygonal meshes. Results from the treatment with latrunculin A and subsequent recovery experiment indicated that filamentous alignment of GFP-PRF1 was likely associated with actin filaments. However, GFP-PRF2 localized to polygonal meshes resembling the endoplasmic reticulum. Our results provide evidence that Arabidopsis profilin isoforms PRF1 and PRF2 have different biochemical affinities for poly-L-proline and G-actin, and show distinctive localizations in living cells. These data suggest that PRF1 and PRF2 are functionally different isoforms.
Abstract (Browse 2242)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Accumulation and Dynamic Trends of Triterpenoid Saponin in Vegetative Organs of Achyranthus bidentata
Author: Jinting Li and Zhenghai Hu
Journal of Integrative Plant Biology 2009 51(2): 122-129
DOI: 10.1111/j.1744-7909.2008.00764.x
      
    The relationship between structural features of various vegetative organs and triterpenoid saponin accumulation in Achyranthus bidentata Blume was investigated using anatomy, histochemistry and phytochemistry. The results showed that the primary and secondary structures of roots, and the structures of stems and leaves of A. bidentata, were similar to those of ordinary dicotyledonous plants. The enlargement of its roots, however, was primarily associated with growth and differentiation of tertiary structures. There were collateral medullary vascular bundles in addition to the normal vascular bundles in the stem. The tertiary structure was not only main parts in the roots of A.bidentata, but also important storage region of triterpenoid saponin in its growth and development. The stem may be the essential transport organ of triterpenoid saponin, while palisade tissue cells may be the primary synthesis location. In November, the total quantity of triterpenoid saponin and overall biomass in the roots reach a maximum level. This was the best time, therefore, to harvest the roots and corresponded to the traditional harvest period. Despite the withered appearance of leaves, stems also contained substantial amounts of triterpenoid saponin, and it was recommended that the stems of A. bidentata should be utilized.
Abstract (Browse 1222)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Overexpression of a New Putative Membrane Protein Gene AtMRB1 Results in Organ Size Enlargement in Arabidopsis
Author: Hua Guan, Dingming Kang, Min Fan, Zhangliang Chen and Li-Jia Qu
Journal of Integrative Plant Biology 2009 51(2): 130-139
DOI: 10.1111/j.1744-7909.2008.00795.x
      
    Arabidopsis AtMRB1 is predicted to encode a novel protein of 432 amino acid residues in length, with four putative trans-membrane domains. In the present study, characterization of AtMRB1 is conducted. Green fluorescent protein (GFP) fusion protein assay showed that AtMRB1 was located in the plasma membrane. Transgenic lines overexpressing AtMRB1 driven by a CaMV 35S promoter were generated. Statistic analysis showed that, during the seedling stage, the organ sizes of the transgenic lines including hypocotyl length, root length and root weight were significantly larger than those of the wild type plants under both light and dark conditions. In the adult plant stage, the AtMRB1 overexpressor plants were found to have larger organ sizes in terms of leaf length and width, and increased number of cauline leaves and branches when bolting. Further observation indicated that the larger leaf size phenotype was due to a larger number of mesophyll cells, the size of which was not altered. Quantitative real-time polymerase chain reaction analysis showed that the transcription of ANT, ROT3 and GRF5 were upregulated in the AtMRB1-overexpressor plants. These data suggest that AtMRB1 is possibly a positive regulator of organ size development in Arabidopsis, mainly through cell number control.
Abstract (Browse 1720)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Distribution of an Ankyrin-repeat Protein on the Endoplasmic Reticulum in Arabidopsis
Author: Liqin Wei and Yan Li
Journal of Integrative Plant Biology 2009 51(2): 140-146
DOI: 10.1111/j.1744-7909.2008.00791.x
      
    There are many ankyrin-repeat proteins in plant cells. However, the distribution and function of these proteins are mostly unclear. By RT-PCR, a gene encoding an ankyrin-like protein was cloned from Arabidopsis and named AtANK1 (GenBank accession no. NM_120340). The 6-His-tagged AtAnk1-N fusion protein was affinity-purified and its rabbit polyclonal antibody was obtained. Immuno-blotting with the purified anti-AtAnk1-N polyclonal antibody revealed that the relative molecular weight of the AtANK1 protein was about 76 kDa. By immunoflorescence labeling and immuno-gold labeling with the purified anti-AtAnk1-N polyclonal antibody, coupled with confocal and transmission electron microscopy observation, AtANK1 was found to be distributed on the membrane of the endoplasmic reticulum in Arabidopsis cells. Based on these results, we suggested that AtANK1 might be involved in ER-related protein localization and sorting in plant cells.
Abstract (Browse 1701)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Effects of Irradiance and Temperature on the Photosynthesis and Vegetative Propagation of Caulerpa serrulata
Author: Demao Li, Guangce Wang, Limei Chen, Fang Lu and Zonggen Shen
Journal of Integrative Plant Biology 2009 51(2): 147-154
DOI: 10.1111/j.1744-7909.2008.00762.x
      
    Responses of the photosynthetic activity of Phaeodactylum tricornutum (Bacillariophyta) to organic carbon glycerol were investigated. The growth rate, photosynthetic pigments, 77 K fluorescence spectra, and chloroplast ultrastructure of P. tricornutum were examined under photoautotrophic, mixotrophic, and photoheterotrophic conditions. The results showed that the specific growth rate was the fastest under mixotrophic condition. The cell photosynthetic pigment content and values of Chl a/Chl c were reduced under mixotrophic and photoheterotrophic conditions. The value of carotenoid/Chl a was enhanced under mixotrophic condition, but was decreased under photoheterotrophic condition. In comparison with photoautotrophic condition, the fluorescence emission peaks and fluorescence excitation peaks were not shifted. The relative fluorescence of PS I and PS II and the values of F685/F710 and F685/F738 were decreased. Chloroplast thylakoid pairs were less packed under mixotrophic and photoheterotrophic conditions. There were a strong correlation between degree of chloroplast thylakoid packing and the excitation energy kept in PS II. These results suggested that the PS II activity was reduced by glycerol under mixotrophic conditions, thereby leading to repression of the photosynthetic activity.
Abstract (Browse 1553)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Identification and expression of floral organ homeotic genes from Alpinia oblongifolia (Zingiberaceae)
Author: Yong-Mei Xia, Xue-Mei Gao and Qing-Jun Li
Journal of Integrative Plant Biology 2009 51(2): 155-166
DOI: 10.1111/j.1744-7909.2008.00782.x
      
    Current understanding of the ABC program has provided a new set of characters to evaluate floral evolution. However, what is still lacking is a clear assessment of this genetic program across monocots. Here, to investigate the evolution of members of class A and B genes in monocots, we report the sequence characteristic and transcript expression of three new MADS-box genes in Alpinia oblongifolia Hayata. Sequence and phylogenetic analysis reveales that these genes are FUL-like and AP3-like. Therefore, they were termed AoFL1, AoFL2 and AoAP3. AoFL1 contains the FUL motif, but AoFL2 lacks this motif. Their expression revealed by in situ hybridization may reflect the ancestral function of FUL-like genes in the specification of inflorescence and floral meristems. The AoAP3 gene contains two conserved motifs, the PI-derived and paleoAP3 motifs. The AoAP3 transcripts located to the corolla and stamen, and hybridization signals were detected in the central whorl. These expression patterns suggest that the functions of homologous organ identity genes are diversified in Alpinia oblongifolia Hayata. The implications of these findings on the conservation of homologous gene function are discussed.
Abstract (Browse 1846)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Plant-environmental Interactions
Riboflavin-induced Priming for Pathogen Defense in Arabidopsis thaliana
Author: Shujian Zhang, Xue Yang, Maowu Sun, Feng Sun, Sheng Deng and Hansong Dong
Journal of Integrative Plant Biology 2009 51(2): 167-174
DOI: 10.1111/j.1744-7909.2008.00763.x
      
    Riboflavin (vitamin B2) participates in a variety of redox processes that affect plant defense responses. Previously we have shown that riboflavin induces pathogen resistance in the absence of hypersensitive cell death (HCD) in plants. Herein, we report that riboflavin induces priming of defense responses in Arabidopsis thaliana toward infection by virulent Pseudomonas syringae pv. tomato DC3000 (Pst). Induced resistance was mechanistically connected with the expression of defense response genes and cellular defense events, including H2O2 burst, HCD, and callose deposition in the plant. Riboflavin treatment and inoculation of plants with Pst were neither active but both synergized to induce defense responses. The priming process needed NPR1 (essential regulator of systemic acquired resistance) and maintenance of H2O2 burst but was independent of salicylic acid, jasmonic acid, ethylene, and abscisic acid. Our results suggest that the role of riboflavin in priming defenses is subject to signaling process distinct from the known pathways of hormone signal transduction.
Abstract (Browse 1885)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Nucleotide Variation in the NCED3 Region of Arabidopsis thaliana and its Association Study with Abscisic Acid Content under Drought Stress
Author: Gang-Ping Hao, Xiu-Hai Zhang, Yong-Qin Wang, Zhong-Yi Wu and Cong-Lin Huang
Journal of Integrative Plant Biology 2009 51(2): 175-183
DOI: 10.1111/j.1744-7909.2008.00786.x
      
    Drought tolerance is a comprehensive quantitative trait being understood further at the molecular genetic level. Abscisic acid (ABA) is the main drought induced hormone which regulates the expression of many genes related to drought responses. Nine-cis-epoxycarotenoid dioxygenase (NCED3) is thought to be a key enzyme in ABA biosynthesis. In this paper, we measured the times of ABA content increase under drought stress, and sequenced and compared the sequence of AtNCED3 among 22 Arabidopsis thaliana accessions. The results showed that the times of ABA content increase under drought stress was highly variable among these accessions. High density of single nucleotide polymorphism (SNP) and insertion/deletion (Indel) were found in AtNCED3 region, on average 1 SNP per 87.4bp and 1 indel per 502 bp. Nucleotide diversity was significantly lower in coding region than that in non-coding region. The results of association study with ANOVA analysis suggested that the 274th site (PnS) and the 327th site (P nR) amino acid variations might be the cause of ABA content increase of 163av accession under drought stress.
Abstract (Browse 1785)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Ethylene Response Factor TERF1 Enhances Glucose Sensitivity in Tobacco through Activating the Expression of Sugar-related Genes
Author: Ang Li, Zhijin Zhang, Xue-Chen Wang and Rongfeng Huang
Journal of Integrative Plant Biology 2009 51(2): 184-193
DOI: 10.1111/j.1744-7909.2008.00794.x
      
    Ethylene response factor (ERF) proteins are important plant-specific transcription factors. Increasing evidences show that ERF proteins regulate plant pathogen resistance, abiotic stress response and plant development through interaction with different stress responsive pathways. Previously, we revealed that overexpression of TERF1 in tobacco activates a cluster gene expression through interacting with GCC box and DRE, resulting in enhanced sensitivity to ABA and tolerance to drought, and dark green leaves of mature plants, indicating that TERF1 participates in the integration of ethylene and osmotic responses. Here we further report that overexpression of TERF1 confers sugar response in tobacco. Analysis of the novel isolated tomato TERF1 promoter provides the information that there are many cis-acting elements, including sugar responsive elements SURE and W box, suggesting that TERF1 might be sugar inducible. This prediction is confirmed by RT-PCR amplification that transcripts of TERF1 are accumulated in tomato seedlings after application of glucose. Further investigation indicates that expression of TERF1 in tobacco enhances sensitivity to glucose during seed germination, root and seedling development, showing decrease of the fresh weight and root elongation under glucose treatment. Detailed investigations evidence that TERF1 interacts with sugar responsive cis-acting element SURE and activates the expression of sugar response genes, establishing the transcriptional regulation of TERF1 in sugar response. Therefore, our results deepen our understanding of glucose response mediated by ERF protein TERF1 in tobacco.
Abstract (Browse 2081)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
UV-B-induced Oxidative Damage and Protective Role of Exopolysaccharides in Desert Cyanobacterium Microcoleus vaginatus
Author: Lan-Zhou Chen, Gao-Hong Wang, Song Hong, An Liu, Cheng Li and Yong-Ding Liu
Journal of Integrative Plant Biology 2009 51(2): 194-200
DOI: 10.1111/j.1744-7909.2008.00784.x
      
    UV-B-induced oxidative damage and the protective effect of exopolysaccharides (EPS) in Microcoleus vaginatus, a cyanobacterium isolated from desert crust, were investigated. After being irradiated with UV-B radiation, photosynthetic activity (Fv/Fm), cellular total carbohydrates, EPS and sucrose production of irradiated cells decreased, while reducing sugars, reactive oxygen species (ROS) generation, malondialdehyde (MDA) production and DNA strand breaks increased significantly. However, when pretreated with 100 mg/L exogenous EPS, EPS production in the culture medium of UVB stressed cells decreased significantly; Fv/Fm, cellular total carbohydrates, reducing sugars and sucrose synthase (SS) activity of irradiated cells increased significantly, while ROS generation, MDA production and DNA strand breaks of irradiated cells decreased significantly. The results suggested that EPS exhibited a significant protective effect on DNA strand breaks and lipid peroxidation by effectively eliminating ROS induced by UV-B radiation in M. vaginatus.
Abstract (Browse 1366)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Molecular Ecology and Evolution
Withania somnifera L. (Ashwagandha): A novel source of L asparaginase
Author: Vishal P.Oza, Shraddha D. Trivedi, Pritesh P. Parmar and R.B.Subramanian
Journal of Integrative Plant Biology 2009 51(2): 201-206
DOI: 10.1111/j.1744-7909.2008.00779.x
      
    Different parts of plant species belonging to Solanaceae and Fabaceae families were screened for L -asparaginase enzyme (E.C.3.5.1.1.). Among 34 plant species screened for L-asparaginase enzyme, Withania somnifera was identified as potential source of the enzyme on the basis of high specific activity of the enzyme. The enzyme was purified and characterized from Withania somnifera, a popular medicinal plant in South East Asia and Southern Europe. Purification was carried out by a combination of protein precipitation with ammonium sulfate as well as Sephadex-gel filtration. The purified enzyme is a homodimer, with a molecular mass of 72 0.5 kDa as estimated by SDS-PAGE and Size exclusion chromatography. The enzyme has a pH optimum of 8.5 and an optimum temperature of 37C. The Km value for the enzyme is 6.1 x 10-2 mM. Its the first report for L-asparaginase from Withania somnifera a traditionally used Indian medicinal plant.
Abstract (Browse 1751)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Molecular Physiology
Analysis of the Arabidopsis Floral Proteome: Detection of over 2 000 Proteins and Evidence for Posttranslational Modifications  
Author: Baomin Feng, Lianchao Li, Xiaofan Zhou, Bruce Stanley and Hong Ma
Journal of Integrative Plant Biology 2009 51(2): 207-223
DOI: 10.1111/j.1744-7909.2008.00787.x
      
    

The proteome of the Arabidopsis flower has not been extensively studied previously. Here, we report a proteomic analysis of the wild type Arabidopsis flower. Using both two-dimensional electrophoresis/mass spectrometry (2-DGE/MS) and multi-dimensional protein identification technology (MudPIT) approaches, we identified 2 446 proteins. Although a single experiment or analysis uncovered only a subset of the proteins we identified, a combination of multiple experiments and analyses facilitated the detection of a greater number of proteins. When proteins are grouped according to RNA expression levels revealed by microarray experiments, we found that proteins encoded by genes with relatively high levels of expression were detected with greater frequencies. On the other hand, at the level of the individual gene/protein, there was not a good correlation between protein spot intensity and microarray values. We also obtained strong evidence for post-translational modification from 2-DGE and MudPIT data. We detected proteins that are annotated to function in protein synthesis, folding, modification, and degradation, as well as the presence of regulatory proteins such as transcription factors and protein kinases. Finally, sequence and evolutionary analysis of genes for active methyl group metabolisms suggests that these genes are highly conserved. Our results allow the formulation of hypotheses regarding post-translational regulation of proteins in the flower, providing new understanding about Arabidopsis flower development and physiology.

Abstract (Browse 1388)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
 

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