June 2012, Volume 54 Issue 6, Pages 358¨C429.

Cover Caption: Subcellular Localization of AaNhaD
About the cover: The AaNhaD gene from soda lake Alkalimonas amylolytica encodes a Na+/H+ antiporter that plays a crucial role in the bacterium¡¯s resistance to salt/alkali stresses. Zhong et al. (pp. 420¨C429) reported that AaNhaD functions as a pH-dependent tonoplast Na+/H+ antiporter in plant cells and is able to enhance the salinity/alkalinity tolerance in transgenic tobacco BY-2 cells and plants. The cover picture illustrates that AaNhaD proteins are located primarily in the vacuole membranes in a BY-2 cell.


          Invited Expert Reviews
The Genetic Architecture of Flowering Time and Photoperiod Sensitivity in Maize as Revealed by QTL Review and Meta Analysis
Author: Jie Xu, Yaxi Liu, Jian Liu, Moju Cao, Jing Wang, Hai Lan, Yunbi Xu, Yanli Lu, Guangtang Pan and Tingzhao Rong
Journal of Integrative Plant Biology 2012 54(6): 358-373
Published Online: May 14, 2012
DOI: 10.1111/j.1744-7909.2012.01128.x

The control of flowering is not only important for reproduction, but also plays a key role in the processes of domestication and adaptation. To reveal the genetic architecture for flowering time and photoperiod sensitivity, a comprehensive evaluation of the relevant literature was performed and followed by meta analysis. A total of 25 synthetic consensus quantitative trait loci (QTL) and four hot-spot genomic regions were identified for photoperiod sensitivity including 11 genes related to photoperiod response or flower morphogenesis and development. Besides, a comparative analysis of the QTL for flowering time and photoperiod sensitivity highlighted the regions containing shared and unique QTL for the two traits. Candidate genes associated with maize flowering were identified through integrated analysis of the homologous genes for flowering time in plants and the consensus QTL regions for photoperiod sensitivity in maize (Zea mays L.). Our results suggest that the combination of literature review, meta-analysis and homologous blast is an efficient approach to identify new candidate genes and create a global view of the genetic architecture for maize photoperiodic flowering. Sequences of candidate genes can be used to develop molecular markers for various models of marker-assisted selection, such as marker-assisted recurrent selection and genomic selection that can contribute significantly to crop environmental adaptation.

Xu J, Liu Y, Liu J, Cao M, Wang J, Lan H, Xu Y, Lu Y, Pan G, Rong T (2012) The genetic architecture of flowering time and photoperiod sensitivity in maize as revealed by QTL review and meta analysis. J. Integr. Plant Biol. 54(6), 358–373.

Abstract (Browse 1858)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Plant-environmental Interactions
Nitrogen Under- and Over-supply Induces Distinct Protein Responses in Maize Xylem Sap  
Author: Chengsong Liao, Renyi Liu, Fusuo Zhang, Chunjian Li and Xuexian Li
Journal of Integrative Plant Biology 2012 54(6): 374-387
Published Online: April 14, 2012
DOI: 10.1111/j.1744-7909.2012.01122.x

Xylem sap primarily transports water and mineral nutrients such as nitrogen (N) from roots to shoots in vascular plants. However, it remains largely unknown how nitrogenous compounds, especially proteins in xylem sap, respond to N under- or over-supply. We found that reducing N supply increased amino-N percentage of total N in maize (Zea mays L.) xylem sap. Proteomic analysis showed that 23 proteins in the xylem sap of maize plants, including 12 newly identified ones, differentially accumulated in response to various N supplies. Fifteen of these 23 proteins were primarily involved in general abiotic or biotic stress responses, whereas the other five proteins appeared to respond largely to N under- or over-supply, suggesting distinct protein responses in maize xylem upon N under- and over-supply. Furthermore, one putative xylanase inhibitor and two putative O-glycosyl hydrolases had preferential gene expression in shoots.

Liao C, Liu R, Zhang F, Li C, Li X (2012) Nitrogen under- and over-supply induces distinct protein responses in maize xylem sap. J. Integr. Plant Biol. 54(6), 374–387.

Abstract (Browse 2176)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Somatic Embryogenesis Receptor Kinases Control Root Development Mainly via Brassinosteroid-Independent Actions in Arabidopsis thaliana
Author: Junbo Du, Hongju Yin, Shasha Zhang, Zhuoyun Wei, Baolin Zhao, Jinghua Zhang, Xiaoping Gou, Honghui Lin, and Jia Li
Journal of Integrative Plant Biology 2012 54(6): 388-399
Published Online: April 24, 2012
DOI: 10.1111/j.1744-7909.2012.01124.x

Brassinosteroids (BRs), a group of plant steroidal hormones, play critical roles in many aspects of plant growth and development. Previous studies showed that BRI1-mediated BR signaling regulates cell division and differentiation during Arabidopsis root development via interplaying with auxin and other phytohormones. Arabidopsis somatic embryogenesis receptor-like kinases (SERKs), as co-receptors of BRI1, were found to play a fundamental role in an early activation step of BR signaling pathway. Here we report a novel function of SERKs in regulating Arabidopsis root development. Genetic analyses indicated that SERKs control root growth mainly via a BR-independent pathway. Although BR signaling pathway is completely disrupted in the serk1 bak1 bkk1 triple mutant, the root growth of the triple mutant is much severely damaged than the BR deficiency or signaling null mutants. More detailed analyses indicated that the triple mutant exhibited drastically reduced expression of a number of genes critical to polar auxin transport, cell cycle, endodermis development and root meristem differentiation, which were not observed in null BR biosynthesis mutant cpd and null BR signaling mutant bri1-701.

Du J, Yin H, Zhang S, Wei Z, Zhao B, Zhang J, Gou X, Lin H, Li J (2012) Somatic embryogenesis receptor kinases control root development mainly via brassinosteroid-independent actions in Arabidopsis thaliana. J. Integr. Plant Biol. 54(6), 388–399.

Abstract (Browse 1963)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Characterization of Two Putative Protein Phosphatase Genes and Their Involvement in Phosphorus Efficiency in Phaseolus vulgaris  
Author: Cui-Yue Liang, Zhi-Jian Chen, Zhu-Fang Yao, Jiang Tian and Hong Liao
Journal of Integrative Plant Biology 2012 54(6): 400-411
Published Online: May 10, 2012
DOI: 10.1111/j.1744-7909.2012.01126.x

Protein dephosphorylation mediated by protein phosphatases plays a major role in signal transduction of plant responses to environmental stresses. In this study, two putative protein phosphatases, PvPS2:1 and PvPS2:2 were identified and characterized in bean (Phaseolus vulgaris). The two PvPS2 members were found to be localized to the plasma membrane and the nucleus by transient expression of PvPS2:GFP in onion epidermal cells. Transcripts of the two PvPS2 genes were significantly increased by phosphate (Pi) starvation in the two bean genotypes, G19833 (a P-efficient genotype) and DOR364 (a P-inefficient genotype). However, G19833 exhibited higher PvPS2:1 expression levels than DOR364 in both leaves and roots during Pi starvation. Increased transcription of PvPS2:1 in response to Pi starvation was further verified through histochemical analysis of PvPS2:1 promoter fusion ß-glucuronidase (GUS) in transgenic Arabidopsis plants. Analysis of PvPS2:1 overexpression lines in bean hairy roots and Arabidopsis showed that PvS2:1 was involved in root growth and P accumulation. Furthermore, expression levels of two Pi starvation responsive genes were upregulated and the APase activities were enhanced in the overexpressing PvPS2:1 Arabidopsis lines. Taken together, our results strongly suggested that PvPS2:1 positively regulated plant responses to Pi starvation, and could be further targeted as a candidate gene to improve crop P efficiency.

Liang CY, Chen ZJ, Yao ZF, Tian J, Liao H (2012) Characterization of two putative protein phosphatase genes and their involvement in phosphorus efficiency in Phaseolus vulgaris. J. Integr. Plant Biol. 54(6), 400–411.

Abstract (Browse 2208)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Ectopic Expression of a Bacterium NhaD-type Na+/H+ Antiporter Leads to Increased Tolerance to Combined Salt/Alkali Stresses
Author: Nai-Qin Zhong, Li-Bo Han, Xiao-Min Wu, Li-Li Wang, Fang Wang, Yan-He Ma and Gui-Xian Xia
Journal of Integrative Plant Biology 2012 54(6): 412-421
Published Online: May 14, 2012
DOI: 10.1111/j.1744-7909.2012.01129.x

AaNhaD, a gene isolated from the soda lake alkaliphile Alkalimonas amylolytica, encodes a Na+/H+ antiporter crucial for the bacterium’s resistance to salt/alkali stresses. However, it remains unknown whether this type of bacterial gene may be able to increase the tolerance of flowering plants to salt/alkali stresses. To investigate the use of extremophile genetic resources in higher plants, transgenic tobacco BY-2 cells and plants harboring AaNhaD were generated and their stress tolerance was evaluated. Ectopic expression of AaNhaD enhanced the salt tolerance of the transgenic BY-2 cells in a pH-dependent manner. Compared to wild-type controls, the transgenic cells exhibited increased Na+ concentrations and pH levels in the vacuoles. Subcellular localization analysis indicated that AaNhaD-GFP fusion proteins were primarily localized in the tonoplasts. Similar to the transgenic BY-2 cells, AaNhaD-overexpressing tobacco plants displayed enhanced stress tolerance when grown in saline-alkali soil. These results indicate that AaNhaD functions as a pH-dependent tonoplast Na+/H+ antiporter in plant cells, thus presenting a new avenue for the genetic improvement of salinity/alkalinity tolerance.

Zhong NQ, Han LB, Wu XM, Wang LL, Wang F, Ma YH, Xia GX (2012) Ectopic expression of a bacterium NhaD-type Na+/H+ antiporter leads to increased tolerance to combined salt/alkali stresses. J. Integr. Plant Biol. 54(6), 412–421.

Abstract (Browse 1730)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Molecular Physiology
Virus-induced Gene Silencing in Eggplant (Solanum melongena)
Author: Haiping Liu, Daqi Fu, Benzhong Zhu, Huaxue Yan, Xiaoying Shen, Jinhua Zuo, Yi Zhu and Yunbo Luo
Journal of Integrative Plant Biology 2012 54(6): 422-429
Published Online: June 12, 2012
DOI: 10.1111/j.1744-7909.2012.01102.x

Eggplant (Solanum melongena) is an economically important vegetable requiring investigation into its various genomic functions. The current limitation in the investigation of genomic function in eggplant is the lack of effective tools available for conducting functional assays. Virus-induced gene silencing (VIGS) has played a critical role in the functional genetic analyses. In this paper, TRV-mediated VIGS was successfully elicited in eggplant. We first cloned the CDS sequence of PDS (PHYTOENE DESATURASE) in eggplant and then silenced the PDS gene. Photo-bleaching was shown on the newly-developed leaves four weeks after agroinoculation, indicating that VIGS can be used to silence genes in eggplant. To further illustrate the reliability of VIGS in eggplant, we selected Chl H, Su and CLA1 as reporters to elicit VIGS using the high-pressure spray method. Suppression of Chl H and Su led to yellow leaves, while the depletion of CLA1 resulted in albino. In conclusion, four genes, PDS, Chl H, Su (Sulfur), CLA1, were down-regulated significantly by VIGS, indicating that the VIGS system can be successfully applied in eggplant and is a reliable tool for the study of gene function.

Liu H, Fu D, Zhu B, Yan H, Shen X, Zuo J, Zhu Y, Luo Y (2012) Virus-induced gene silencing in eggplant (Solanum melongena). J. Integr. Plant Biol. 54(6), 422–429.

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