A High-Resolution Transcript Profile across the Wood-Forming Meristem of Poplar Identifies Potential Regulators of Cambial Stem Cell Identity[W]

Schrader, Jarmo; Nilsson, Jeanette; Mellerowicz, Ewa J.; Berglund, Anders; Nilsson, Peter; Hertzberg, Magnus; Sandberg, Göran

doi:10.1105/tpc.104.024190

Cited by 360 publications

(347 citation statements)

References 66 publications

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“…In addition, by incorporating the different microarray data, we were capable to identify different subsets of NAC genes displaying specifically high expression levels in phloem, differentiating xylem and mature xylems, respectively. The expression levels of five NAC genes including PNAC070, 086, 121 and 122 were peaked exclusively in differentiating xylems supported by two independent microarray datasets (Figure 6C and 6G) [87,88]. Among them, PNAC070 (PtWND5A), PNAC086 (PtWND1A) and PNAC008 (PtWND3A) were demonstrated in previous studies as putative redundant homologs involved in Populus wood formation [19].…”

Section: Resultssupporting

confidence: 61%

Comprehensive Analysis of NAC Domain Transcription Factor Gene Family in Populus trichocarpa

et al. 2010

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BackgroundNAC (NAM, ATAF1/2 and CUC2) domain proteins are plant-specific transcriptional factors known to play diverse roles in various plant developmental processes. NAC transcription factors comprise of a large gene family represented by more than 100 members in Arabidopsis, rice and soybean etc. Recently, a preliminary phylogenetic analysis was reported for NAC gene family from 11 plant species. However, no comprehensive study incorporating phylogeny, chromosomal location, gene structure, conserved motifs, and expression profiling analysis has been presented thus far for the model tree species Populus.ResultsIn the present study, a comprehensive analysis of NAC gene family in Populus was performed. A total of 163 full-length NAC genes were identified in Populus, and they were phylogeneticly clustered into 18 distinct subfamilies. The gene structure and motif compositions were considerably conserved among the subfamilies. The distributions of 120 Populus NAC genes were non-random across the 19 linkage groups (LGs), and 87 genes (73%) were preferentially retained duplicates that located in both duplicated regions. The majority of NACs showed specific temporal and spatial expression patterns based on EST frequency and microarray data analyses. However, the expression patterns of a majority of duplicate genes were partially redundant, suggesting the occurrence of subfunctionalization during subsequent evolutionary process. Furthermore, quantitative real-time RT-PCR (RT-qPCR) was performed to confirm the tissue-specific expression patterns of 25 NAC genes.ConclusionBased on the genomic organizations, we can conclude that segmental duplications contribute significantly to the expansion of Populus NAC gene family. The comprehensive expression profiles analysis provides first insights into the functional divergence among members in NAC gene family. In addition, the high divergence rate of expression patterns after segmental duplications indicates that NAC genes in Populus are likewise to have been retained by substantial subfunctionalization. Taken together, our results presented here would be helpful in laying the foundation for functional characterization of NAC gene family and further gaining an understanding of the structure-function relationship between these family members.

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Section: Resultssupporting

confidence: 61%

Comprehensive Analysis of NAC Domain Transcription Factor Gene Family in Populus trichocarpa

et al. 2010

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“…On the basis of microarray expression data (Schrader et al, 2004) and immunolocalization analyses (Srivastava et al, 2007) regarding hipI-SOD, vascular tissue was chosen to check the expression patterns of all three transcripts (hipI-SODC1s, hipISODC1b, and hipI-SODC2). Since the hipI-SOD genes differ in their 3# UTRs, specific PCR primers (see "Materials and Methods"; Table II) for hipI-SODC1s, hipI-SODC1b, and hipI-SODC2 were designed to amplify cDNA from phloem, cambium, and xylem tissues.…”

Section: Expression Of Hipi-sod In Vascular Tissuementioning

confidence: 99%

Alternative Splicing Studies of the Reactive Oxygen Species Gene Network inPopulusReveal Two Isoforms of High-Isoelectric-Point Superoxide Dismutase

Srivastava

Chibani

et al. 2009

Plant Physiology

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Recent evidence has shown that alternative splicing (AS) is widely involved in the regulation of gene expression, substantially extending the diversity of numerous proteins. In this study, a subset of expressed sequence tags representing members of the reactive oxygen species gene network was selected from the PopulusDB database to investigate AS mechanisms in Populus. Examples of all known types of AS were detected, but intron retention was the most common. Interestingly, the closest Arabidopsis (Arabidopsis thaliana) homologs of half of the AS genes identified in Populus are not reportedly alternatively spliced. Two genes encoding the protein of most interest in our study (high-isoelectric-point superoxide dismutase [hipI-SOD]) have been found in black cottonwood (Populus trichocarpa), designated PthipI-SODC1 and PthipI-SODC2. Analysis of the expressed sequence tag libraries has indicated the presence of two transcripts of PthipI-SODC1 (hipI-SODC1b and hipISODC1s). Alignment of these sequences with the PthipI-SODC1 gene showed that hipI-SODC1b was 69 bp longer than hipISODC1s due to an AS event involving the use of an alternative donor splice site in the sixth intron. Transcript analysis showed that the splice variant hipI-SODC1b was differentially expressed, being clearly expressed in cambial and xylem, but not phloem, regions. In addition, immunolocalization and mass spectrometric data confirmed the presence of hipI-SOD proteins in vascular tissue. The functionalities of the spliced gene products were assessed by expressing recombinant hipI-SOD proteins and in vitro SOD activity assays.

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“…S2H). In poplar, PtHK3a and PtHK3b show the highest cambial expression, peaking in the same zone as the marker gene for cambial cell identity, PtANT (27) (Fig. 1 B, C, and E and Fig.…”

Section: The Cre Cytokinin Receptor Gene Family Is Conserved Betweenmentioning

confidence: 99%

Cytokinin signaling regulates cambial development in poplar

Nieminen

Immanen²,

Laxell³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

245

208

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Although a substantial proportion of plant biomass originates from the activity of vascular cambium, the molecular basis of radial plant growth is still largely unknown. To address whether cytokinins are required for cambial activity, we studied cytokinin signaling across the cambial zones of 2 tree species, poplar (Populus trichocarpa) and birch (Betula pendula). We observed an expression peak for genes encoding cytokinin receptors in the dividing cambial cells. We reduced cytokinin levels endogenously by engineering transgenic poplar trees (P. tremula ؋ tremuloides) to express a cytokinin catabolic gene, Arabidopsis CYTOKININ OXI-DASE 2, under the promoter of a birch CYTOKININ RECEPTOR 1 gene. Transgenic trees showed reduced concentration of a biologically active cytokinin, correlating with impaired cytokinin responsiveness. In these trees, both apical and radial growth was compromised. However, radial growth was more affected, as illustrated by a thinner stem diameter than in WT at same height. To dissect radial from apical growth inhibition, we performed a reciprocal grafting experiment. WT scion outgrew the diameter of transgenic stock, implicating cytokinin activity as a direct determinant of radial growth. The reduced radial growth correlated with a reduced number of cambial cell layers. Moreover, expression of a cytokinin primary response gene was dramatically reduced in the thin-stemmed transgenic trees. Thus, a reduced level of cytokinin signaling is the primary basis for the impaired cambial growth observed. Together, our results show that cytokinins are major hormonal regulators required for cambial development.cambial activity ͉ cambium ͉ secondary development ͉ Populus ͉ CYTOKININ OXIDASE

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A High-Resolution Transcript Profile across the Wood-Forming Meristem of Poplar Identifies Potential Regulators of Cambial Stem Cell Identity[W]

Cited by 360 publications

References 66 publications

Comprehensive Analysis of NAC Domain Transcription Factor Gene Family in Populus trichocarpa

Comprehensive Analysis of NAC Domain Transcription Factor Gene Family in Populus trichocarpa

Alternative Splicing Studies of the Reactive Oxygen Species Gene Network inPopulusReveal Two Isoforms of High-Isoelectric-Point Superoxide Dismutase

Cytokinin signaling regulates cambial development in poplar

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