November 2014, Volume 56 Issue 11, Pages 1034每1105.


Cover Caption: A Germ Cell-Specific AGO in Maize
About the cover: Argonaute (AGO) proteins are core factors of the RNAinduced silencing complex that guides sRNAs to their target genes. In this issue (pp. 1042每1052), Zhai et al. studied AGOs expressed in maize reproductive tissues, and identified the ZmAGO18b as a member highly accumulated in meiotic microsporocytes, suggesting its role in cell-type specific gene silencing.

 

          Molecular Physiology
Knockdown of LjALD1, AGD2-like defense response protein 1, influences plant growth and nodulation in Lotus japonicus
Author: Wei Chen, Xueliu Li, Lu Tian, Pingzhi Wu, Meiru Li, Huawu Jiang, Yaping Chen and Guojiang Wu
Journal of Integrative Plant Biology 2014 56(11): 1034每1041
Published Online: May 5, 2014
DOI: 10.1111/jipb.12211
      
    

The discovery of the enzyme L,L-diaminopimelate aminotransferase (LL-DAP-AT, EC 2.6.1.83) uncovered a unique step in the L-lysine biosynthesis pathway in plants. In Arabidopsis thaliana, LL-DAP-AT has been shown to play a key role in plant-pathogen interactions by regulation of the salicylic acid (SA) signaling pathway. Here, a full-length cDNA of LL-DAP-AT named as LjALD1 from Lotus japonicus (Regel) Larsen was isolated. The deduced amino acid sequence shares 67% identity with the Arabidopsis aminotransferase AGD2-LIKE DEFENSE RESPONSE PROTEIN1 (AtALD1) and is predicted to contain the same key elements: a conserved aminotransferase domain and a pyridoxal-5'-phosphate cofactor binding site. Quantitative real-time PCR analysis showed that LjALD1 was expressed in all L. japonicus tissues tested, being strongest in nodules. Expression was induced in roots that had been infected with the symbiotic rhizobium Mesorhizobium loti or treated with SA agonist benzo-(1, 2, 3)-thiadiazole-7-carbothioic acid. LjALD1 Knockdown exhibited a lower SA content, an increased number of infection threads and nodules, and a slight reduction in nodule size. In addition, compared with wild-type, root growth was increased and shoot growth was suppressed in LjALD1 RNAi plant lines. These results indicate that LjALD1 may play important roles in plant development and nodulation via SA signaling in L. japonicus.

 

Chen W, Li X, Tian L, Wu P, Li M, Jiang H, Chen Y, Wu G (2014) Knockdown of LjALD1, AGD2坼like defense response protein 1, influences plant growth and nodulation in Lotus japonicus. J Integr Plant Biol 56: 1034–1041. doi: 10.1111/jipb.12211

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Identification and characterization of Argonaute gene family and meiosis-enriched Argonaute during sporogenesis in maize
Author: Lihong Zhai, Wei Sun, Ke Zhang, Haitao Jia, Lei Liu, Zhijie Liu, Feng Teng and Zuxin Zhang
Journal of Integrative Plant Biology 2014 56(11): 1042每1052
Published Online: April 16, 2014
DOI: 10.1111/jipb.12205
      
    

Argonaute (AGO) proteins play a key role in regulation of gene expression through small RNA-directed RNA cleavage and translational repression, and are essential for multiple developmental processes. In the present study, 17 AGO genes of maize (Zea mays L., ZmAGOs) were identified using a Hidden Markov Model and validated by rapid amplification of cDNA ends assay. Subsequently, quantitative PCR revealed that expressions of these genes were higher in reproductive than in vegetative tissues. AGOs presented five temporal and spatial expression patterns, which were likely modulated by DNA methylation, 5′-untranslated exons and microRNA-mediated feedback loops. Intriguingly, ZmAGO18b was highly expressed in tassels during meiosis. Furthermore, in situ hybridization and immunofluorescence showed that ZmAGO18b was enriched in the tapetum and germ cells in meiotic anthers. We hypothesized that ZmAGOs are highly expressed in reproductive tissues, and that ZmAGO18b is a tapetum and germ cell-specific member of the AGO family in maize.

 

 Zhai L, Sun W, Zhang K, Jia H, Liu L, Liu Z, Teng F, Zhang Z (2014) Identification and characterization of Argonaute gene family and meiosis坼enriched Argonaute during sporogenesis in maize. J Integr Plant Biol 56: 1042–1052. doi: 10.1111/jipb.12205

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Overexpression of the maize GRF10, an endogenous truncated growth-regulating factor protein, leads to reduction in leaf size and plant height
Author: Lei Wu, Dengfeng Zhang, Ming Xue, Jianjun Qian, Yan He and Shoucai Wang
Journal of Integrative Plant Biology 2014 56(11): 1053每1063
Published Online: May 22, 2014
DOI: 10.1111/jipb.12220
      
    
It has long been thought that growth-regulating factors (GRFs) gene family members act as transcriptional activators to play important roles in multiple plant developmental processes. However, the recent characterization of Arabidopsis GRF7 showed that it functions as a transcriptional repressor of osmotic stress-responsive genes. This highlights the complex and diverse mechanisms by which different GRF members use to take action. In this study, the maize (Zea mays L.) GRF10 was functionally characterized to improve this concept. The deduced ZmGRF10 protein retains the N-terminal QLQ and WRC domains, the characteristic regions as protein-interacting and DNA-binding domains, respectively. However, it lacks nearly the entire C-terminal domain, the regions executing transactivation activity. Consistently, ZmGRF10 protein maintains the ability to interact with GRF-interacting factors (GIFs) proteins, but lacks transactivation activity. Overexpression of ZmGRF10 in maize led to a reduction in leaf size and plant height through decreasing cell proliferation, whereas the yield-related traits were not affected. Transcriptome analysis revealed that multiple biological pathways were affected by ZmGRF10 overexpression, including a few transcriptional regulatory genes, which have been demonstrated to have important roles in controlling plant growth and development. We propose that ZmGRF10 aids in fine-tuning the homeostasis of the GRF-GIF complex in the regulation of cell proliferation.

 

Wu L, Zhang D, Xue M, Qian J, He Y, Wang S (2014) Overexpression of the maize GRF10, an endogenous truncated GRF protein, leads to reduction in leaf size and plant height. J Integr Plant Biol 56:1053–1063. doi: 10.1111/jipb.12220

Abstract (Browse 925)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Plant-environmental Interactions
Comparative proteomic and metabolomic analyses reveal mechanisms of improved cold stress tolerance in bermudagrass (Cynodon dactylon (L.) Pers.) by exogenous calcium  
Author: Haitao Shi, Tiantian Ye, Bao Zhong, Xun Liu and Zhulong Chan
Journal of Integrative Plant Biology 2014 56(11): 1064每1079
Published Online: January 16, 2014
DOI: 10.1111/jipb.12167
      
    

As an important second messenger, calcium is involved in plant cold stress response, including chilling (<20 °C) and freezing (<0 °C). In this study, exogenous application of calcium chloride (CaCl2) improved both chilling and freezing stress tolerances, while ethylene glycol-bis-(β-aminoethyl) ether-N,N,N,N-tetraacetic acid (EGTA) reversed CaCl2 effects in bermudagrass (Cynodon dactylon (L.) Pers.). Physiological analyses showed that CaCl2 treatment alleviated the reactive oxygen species (ROS) burst and cell damage triggered by chilling stress, via activating antioxidant enzymes, non-enzymatic glutathione antioxidant pool, while EGTA treatment had the opposite effects. Additionally, comparative proteomic analysis identified 51 differentially expressed proteins that were enriched in redox, tricarboxylicacid cycle, glycolysis, photosynthesis, oxidative pentose phosphate pathway, and amino acid metabolisms. Consistently, 42 metabolites including amino acids, organic acids, sugars, and sugar alcohols were regulated by CaCl2 treatment under control and cold stress conditions, further confirming the common modulation of CaCl2 treatment in carbon metabolites and amino acid metabolism. Taken together, this study reported first evidence of the essential and protective roles of endogenous and exogenous calcium in bermudagrass response to cold stress, partially via activation of the antioxidants and modulation of several differentially expressed proteins and metabolic homeostasis in the process of cold acclimation.

 

Shi H, Ye T, Zhong B, Liu X, Chan Z (2014) Comparative proteomic and metabolomic analyses reveal mechanisms of improved cold stress tolerance in bermudagrass (Cynodon dactylon (L.) Pers.) by exogenous calcium. J Integr Plant Biol 56: 1064–1079. doi: 10.1111/jipb.12167

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Nitrate induction triggers different transcriptional changes in a high and a low nitrogen use efficiency maize inbred line  
Author: Anita Zamboni, Stefania Astolfi, Sabrina Zuchi, Youry Pii, Katia Guardini, Paola Tononi and Zeno Varanini
Journal of Integrative Plant Biology 2014 56(11): 1080每1094
Published Online: May 7, 2014
DOI: 10.1111/jipb.12214
      
    

In higher plants, NO3 can induce its own uptake and the magnitude of this induction is positively related to the external anion concentration. This phenomenon has been characterized in both herbaceous and woody plants. Here, different adaptation strategies of roots from two maize (Zea mays L., ZmAGOs) inbred lines differing in nitrogen use efficiency (NUE) and exhibiting different timing of induction were discussed by investigating NO3-induced changes in their transcriptome. Lo5 line (high NUE) showing the maximum rate of NO3 uptake 4 h after the provision of 200 μmol/L NO3 treatment modulated a higher number of transcripts relative to T250 (low NUE) that peaked after 12 h. The two inbred lines share only 368 transcripts that are modulated by the treatment with NO3 and behaved differently when transcripts involved in anion uptake and assimilation were analyzed. T250 line responded to the NO3 induction modulating this group of genes as reported for several plant species. On the contrary, the Lo5 line did not exhibit during the induction changes in this set of genes. Obtained data suggest the importance of exploring the physiological and molecular variations among different maize genotypes in response to environmental clues like NO3 provision, in order to understand mechanisms underlying NUE.

 

Zamboni A, Astolfi S, Zuchi S, Pii Y, Guardini K, Tononi P, Varanini Z (2014) Nitrate induction triggers different transcriptional changes in a high and a low nitrogen use efficiency maize inbred line. J Integr Plant Biol 56: 1080–1094. doi: 10.1111/jipb.12214

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          Plant Reproduction
PECTATE LYASE-LIKE10 is associated with pollen wall development in Brassica campestris
Author: Jingjing Jiang, Lina Yao, Youjian Yu, Meiling Lv, Ying Miao and Jiashu Cao
Journal of Integrative Plant Biology 2014 56(11): 1095每1105
Published Online: April 29, 2014
DOI: 10.1111/jipb.12209
      
    

PECTATE LYASE-LIKE10 (PLL10) was previously identified as one of the differentially expressed genes both in microspores during the late pollen developmental stages and in pistils during the fertilization process in Chinese cabbage (Brassica campestris ssp. chinensis). Here, antisense-RNA was used to study the functions of BcPLL10 in Chinese cabbage. Abnormal pollen was identified in the transgenic lines (bcpll10-4, -5, and -6). In fertilization experiments, fewer seeds were harvested when the antisense-RNA lines were used as pollen donor. In vivo and in vitro pollen germination assays less germinated pollen tubes were observed in bcpll10 lines. Scanning electron microscopy observation verified that the tryphine materials were over accumulated around the pollen surface and sticked them together in bcpll10. Moreover, transmission electron microscopy observation revealed that the internal endintine was overdeveloped and predominantly occupied the intine, and disturbed the normal proportional distribution of the two layers in the non-germinal furrow region; and no obvious demarcation existed between them in the germinal furrow region in the bcpll10 pollen. Collectively, this study presented a novel PLL gene that played an important role during the pollen wall development in B. campestris, which may also possess potential importance for male sterility usage in agriculture.

 

Jiang J, Yao L, Yu Y, Lv M, Miao Y, Cao J (2014) PECTATE LYASE坼LIKE10 is associated with pollen wall development in Brassica campestris. J Integr Plant Biol 56: 1095–1105. doi: 10.1111/jipb.12209

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