October 2015, Volume 57 Issue 10, Pages 810每870.


Cover Caption: Reproductive Isolation in Sympatric Mussaenda
Reproductive isolation may lead to formation of new species. In this issue, Luo et al. (pp. 859每870) report that principal pollinators between two sympatric sister species of Mussaenda differed strikingly, and interspecific pollination resulted in significantly reduced pollen tube growth rates. These findings strongly suggest that pre-zygotic isolation plays an important role in limiting gene exchange for species with close phylogenetic relationship. The cover image shows pollen grains germinated on an interspecific stigma.

 

          Cell and Developmental Biology
Arabidopsis SMALL ORGAN 4, a homolog of yeast NOP53, regulates cell proliferation rate during organ growth  
Author: Xiao-Ran Zhang, Zhixiang Qin, Xiao Zhang and Yuxin Hu
Journal of Integrative Plant Biology 2015 57(10): 810每818
Published Online: August 27, 2015
DOI: 10.1111/jipb.12424
      
    

Cell proliferation is a fundamental event essential for plant organogenesis and contributes greatly to the final organ size. Although the control of cell proliferation in plants has been extensively studied, how the plant sets the cell number required for a single organ is largely elusive. Here, we describe the Arabidopsis SMALL ORGAN 4 (SMO4) that functions in the regulation of cell proliferation rate and thus final organ size. The smo4 mutant exhibits a reduced size of organs due to the decreased cell number, and further analysis reveals that such phenotype results from a retardation of the cell cycle progression during organ development. SMO4 encodes a homolog of NUCLEOLAR PROTEIN 53 (NOP53) in Saccharomyces cerevisiae and is expressed primarily in tissues undergoing cell proliferation. Nevertheless, further complementation tests show that SMO4 could not rescue the lethal defect of NOP53 mutant of S. cerevisiae. These results define SMO4 as an important regulator of cell proliferation during organ growth and suggest that SMO4 might have been evolutionarily divergent from NOP53.

 

Zhang XR, Qin Z, Zhang X, Hu Y (2015) Arabidopsis SMALL ORGAN 4, a homolog of yeast NOP53, regulates cell proliferation rate during organ growth. J Integr Plant Biol 57: 810–818 doi: 10.1111/jipb.12424

Abstract (Browse 755)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Cell division is a fundamental cellular event that contributes to the overall organ size in plants. How cell division progression is strictly regulated remains largely elusive during plant organogenesis. Here, the Arabidopsis SMO4, a homologue of yeast NOP53, is shown to regulate cell division progression and thus the final organ size.
The alteration in the architecture of a T-DNA insertion rice mutant osmtd1 is caused by up-regulation of MicroRNA156f  
Author: Qing Liu, Gezhi Shen, Keqin Peng, Zhigang Huang, Jianhua Tong, Mohammed Humayun Kabir, Jianhui Wang, Jingzhe Zhang, Genji Qin and Langtao Xiao
Journal of Integrative Plant Biology 2015 57(10): 819每829
Published Online: February 11, 2015
DOI: 10.1111/jipb.12340
      
    

Plant architecture is an important factor for crop production. Some members of microRNA156 (miR156) and their target genes SQUAMOSA Promoter-Binding Protein-Like (SPL) were identified to play essential roles in the establishment of plant architecture. However, the roles and regulation of miR156 is not well understood yet. Here, we identified a T-DNA insertion mutant Osmtd1 (Oryza sativa multi-tillering and dwarf mutant). Osmtd1 produced more tillers and displayed short stature phenotype. We determined that the dramatic morphological changes were caused by a single T-DNA insertion in Osmtd1. Further analysis revealed that the T-DNA insertion was located in the gene Os08g34258 encoding a putative inhibitor I family protein. Os08g34258 was knocked out and OsmiR156f was significantly upregulated in Osmtd1. Overexpression of Os08g34258 in Osmtd1 complemented the defects of the mutant architecture, while overexpression of OsmiR156f in wild-type rice phenocopied Osmtd1. We showed that the expression of OsSPL3, OsSPL12, and OsSPL14 were significantly downregulated in Osmtd1 or OsmiR156f overexpressed lines, indicating that OsSPL3, OsSPL12, and OsSPL14 were possibly direct target genes of OsmiR156f. Our results suggested that OsmiR156f controlled plant architecture by mediating plant stature and tiller outgrowth and may be regulated by an unknown protease inhibitor I family protein.

 

Liu Q, Shen G, Peng K, Huang Z, Tong J, Kabir MH, Wang J, Zhang J, Qin G, Xiao L (2015) The alteration in the architecture of a T-DNA insertion rice mutant osmtd1 is caused by up-regulation of MicroRNA156f. J Integr Plant Biol 57: 819–829 doi: 10.1111/jipb.12340

Abstract (Browse 1102)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Plant architecture is a key factor affecting crop production. A rice T-DNA insertion mutant Osmtd1 displayed multi-tillering and dwarf phenotypes. Os08g34258 gene encoding an unknown protease inhibitor I family protein was knocked down whereas OsmiR156f was significantly up-regulated in Osmtd1 mutant. Our results suggested that OsMTD1 might regulate plant architecture by controlling OsmiR156f in rice.
          Molecular Physiology
Glucose alleviates cadmium toxicity by increasing cadmium fixation in root cell wall and sequestration into vacuole in Arabidopsis
Author: Yuan-Zhi Shi, Xiao-Fang Zhu, Jiang-Xue Wan, Gui-Xin Li and Shao-Jian Zheng
Journal of Integrative Plant Biology 2015 57(10): 830每837
Published Online: November 17, 2014
DOI: 10.1111/jipb.12312
      
    

Glucose (Glu) is involved in not only plant physiological and developmental events but also plant responses to abiotic stresses. Here, we found that the exogenous Glu improved root and shoot growth, reduced shoot cadmium (Cd) concentration, and rescued Cd-induced chlorosis in Arabidopsis thaliana (Columbia ecotype, Col-0) under Cd stressed conditions. Glucose increased Cd retained in the roots, thus reducing its translocation from root to shoot significantly. The most Cd retained in the roots was found in the hemicellulose 1. Glucose combined with Cd (Glu + Cd) treatment did not affect the content of pectin and its binding capacity of Cd while it increased the content of hemicelluloses 1 and the amount of Cd retained in it significantly. Furthermore, Leadmium Green staining indicated that more Cd was compartmented into vacuoles in Glu + Cd treatment compared with Cd treatment alone, which was in accordance with the significant upregulation of the expression of tonoplast-localized metal transporter genes, suggesting that compartmentation of Cd into vacuoles also contributes to the Glu-alleviated Cd toxicity. Taken together, we demonstrated that Glu-alleviated Cd toxicity is mediated through increasing Cd fixation in the root cell wall and sequestration into the vacuoles.

 

Shi YZ, Zhu XF, Wan JX, Li GX, Zheng SJ (2015) Glucose alleviates cadmium toxicity by increasing cadmium fixation in root cell wall and sequestration into vacuole in Arabidopsis. J Integr Plant Biol 57: 830–837 doi: 10.1111/jipb.12312

Abstract (Browse 878)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Glucose applied exogenously can increase Cd fixation in the root cell wall and sequestration into the vacuoles. As a result, less Cd was translocated to the shoot, thus alleviating the Cd-induced leaf chlorosis in Arabidopsis.
ThERF1 regulates its target genes via binding to a novel cis-acting element in response to salt stress
Author: Liuqiang Wang, Chao Wang, Liping Qin, Wenjin Liu and Yucheng Wang
Journal of Integrative Plant Biology 2015 57(10): 838每847
Published Online: January 31, 2015
DOI: 10.1111/jipb.12335
      
    

Ethylene responsive factors (ERFs) are plant-specific transcription factors that are involved in a variety of biological processes. We previously demonstrated that an ERF gene from Tamarix hispida, ThERF1, encodes a protein binding to GCC-box and DRE motifs and negatively modulates abiotic stress tolerance. In the present study, microarray analysis was performed to study the genes regulated by ThERF1 on a genomic scale. There were 154 and 307 genes (respectively representing 134 and 260 unique genes) significantly up- and downregulated by ThERF1 under salt stress conditions, respectively. A novel motif, named TTG, was identified to be recognized by ThERF1, which commonly presents in the promoters of ThERF1-targeted genes. The TTG motif is also bound by other ERFs of a different subfamily from T. hispida and Arabidopsis, indicating that it is commonly recognized by ERF proteins. The binding affinities of ERFs to the TTG motif are significantly induced by salt stress. The TTG motif is more enriched than the GCC-box and DRE motifs in the promoters of ThERF1-targeted genes. Taken together, these studies suggested that the TTG motif plays an important role in the gene expression regulated by ERFs in response to salt stress.

 

Wang L, Wang C, Qin L, Liu W, Wang Y (2015) ThERF1 regulates its target genes via binding to a novel cis-acting element in response to salt stress. J Integr Plant Biol 57: 838–847 doi: 10.1111/jipb.12335

Abstract (Browse 870)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
We identified that ethylene responsive factor (ERF) can bind to a novel DNA sequence (TTG motif). Most of the ERF regulated genes contain TTG motif rather than GCC-box and DRE motifs in their promoters, suggesting that TTG motif plays an important role in the gene expression regulated by ERFs.
An eukaryotic translation initiation factor, AteIF5A-2, affects cadmium accumulation and sensitivity in Arabidopsis  
Author: Xiao-Yan Xu, Zhong-Jie Ding, Lei Chen, Jin-Ying Yan, Gui-Xin Li and Shao-Jian Zheng
Journal of Integrative Plant Biology 2015 57(10): 848每858
Published Online: January 5, 2015
DOI: 10.1111/jipb.12329
      
    

Cadmium (Cd) is one of the most toxic elements and can be accumulated in plants easily; meanwhile, eIF5A is a highly conserved protein in all eukaryotic organisms. The present work tried to investigate whether eIF5A is involved in Cd accumulation and sensitivity in Arabidopsis (Arabidopsis thaliana L.) by comparing the wild-type Columbia-0 (Col-0) with a knockdown mutant of AteIF5A-2, fbr12-3 under Cd stress conditions. The results showed that the mutant fbr12-3 accumulated more Cd in roots and shoots and had significantly lower chlorophyll content, shorter root length, and smaller biomass, suggesting that downregulation of AteIF5A-2 makes the mutant more Cd sensitive. Real-time polymerase chain reaction revealed that the expressions of metal transporters involved in Cd uptake and translocation including IRT1, ZIP1, AtNramp3, and AtHMA4 were significantly increased but the expressions of PCS1 and PCS2 related to Cd detoxification were decreased notably in fbr12-3 compared with Col-0. As a result, an increase in MDA and H2O2 content but decrease in root trolox, glutathione and proline content under Cd stress was observed, indicating that a severer oxidative stress occurs in the mutant. All these results demonstrated for the first time that AteIF5A influences Cd sensitivity by affecting Cd uptake, accumulation, and detoxification in Arabidopsis.

 

Xu XY, Ding ZJ, Chen L, Yan JY, Li GX, Zheng SJ (2015) An eukaryotic translation initiation factor, AteIF5A-2, affects cadmium accumulation and sensitivity in Arabidopsis. J Integr Plant Biol 57: 848–858 doi: 10.1111/jipb.12329

Abstract (Browse 750)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Mutation of a eukaryotic translation initiation factor AteIF5A-2 increases Cd uptake and accumulation, and decreases Cd detoxification by regulating the expression of metal transporters and ROS metabolism, thus results in the increase of Cd sensitivity in Arabidopsis.
          Plant Reproduction Biology
Reproductive isolation between sympatric sister species, Mussaenda kwangtungensis and M. pubescens var. alba
Author: Zhonglai Luo, Tingting Duan, Shuai Yuan, Shi Chen, Xiufeng Bai and Dianxiang Zhang
Journal of Integrative Plant Biology 2015 57(10): 859每870
Published Online: December 26, 2014
DOI: 10.1111/jipb.12325
      
    

Reproductive isolation defines the biological species concept and plays a key role in the formation and maintenance of species. The relative contributions of different isolating stages has been suggested to be closely associated with phylogenetic relatedness. Few studies have focused on the relative contributions of pre- versus post-zygotic mechanisms, and even fewer have been conducted under strict phylogenetic frameworks. Pre- and post-zygotic reproductive isolation stages have been investigated in the sister species Mussaenda kwangtungensis and M. pubescens var. alba. The two species have partly overlapping distribution ranges and flowering times, while the principal pollinators differed strikingly for them, demonstrating strong pre-zygotic isolations. Natural hybrids were detected by simple sequence repeat markers and their maternal parents were identified based on chloroplast gene sequences. Five out of 81 individuals were suggested to be hybrids that fall into the categories F2, BC1, and BC2 by the NewHybrids analysis. Interspecific crossings resulted in significantly reduced fruit set and seed germination rates. Phylogenetic analysis revealed short Kimura-2-parameter distance between M. kwangtungensis and M. pubescens var. alba. These findings strongly supported the hypothesis that for species with a closer phylogenetic relationship, pre-zygotic isolation plays an important part in limiting gene exchange in sympatric areas.

 

Luo Z, Duan T, Yuan S, Chen S, Bai X, Zhang D (2015) Reproductive isolation between sympatric sister species, Mussaenda kwangtungensis and M. pubescens var.alba. J Integr Plant Biol 57: 859–870 doi: 10.1111/jipb.12325

Abstract (Browse 899)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Reproductive isolation plays a key role in the formation and maintenance of species. Between the sympatric sister species Mussaenda kwangtungensis and M. pubescens var. alba, principal pollinators differed strikingly, strongly supporting the hypothesis that pre-zygotic isolation plays an important part in limiting gene exchange for species with a closer phylogenetic relationship.
 

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