Abstract

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.

Highlights

  • NAC (NAM, ATAF1/2 and CUC2) domain proteins are plant-specific transcriptional factors known to play diverse roles in various plant developmental processes

  • In an attempt to demonstrate the reliability of the identified genes, keyword search with NAM against NCBI nucleotide database was performed, resulting in 153 members which were all included in the NACs identified above

  • The NAC gene family in Populus is by far the largest one compared to the estimates for other plant species, which range from ~105 in Arabidopsis [6], ~140 in rice

Read more

Summary

Introduction

NAC (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. Transcription factors (TFs) are types of proteins that regulate gene expression by binding to specific cis-acting promoter elements, thereby activating or repressing the transcriptional rates. NAC (NAM, ATAF1/2 and CUC2) domain proteins comprise of one of the largest plant-specific TFs represented by ~105 genes in Arabidopsis [6], ~140 genes in rice [7] and ~101 genes in soybean genome [8]. The C-terminal regions of NAC proteins are highly divergent [6,7,8,9,14], and confer the regulation diversities of transcriptional activation activity [11,13,15,16,17,18,19,20,21,22]

Methods
Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call