NAC proteins comprise one of the largest families of transcription factors in the plant genome. They are known to be involved in various aspects of plant development, but the functions of most of them have not yet been determined. ANAC036, a member of the Arabidopsis NAC transcription factor family, contains unique sequences that are conserved among various NAC proteins found in other plant species. Expression analysis of the ANAC036 gene indicated that this gene was strongly expressed in leaves. Transgenic plants overexpressing the ANAC036 gene showed a semidwarf phenotype. The lengths of leaf blades, petioles and stems of these plants were smaller than those in wild-type plants. Microscopy revealed that cell sizes in leaves and stems of these plants were smaller than those in wild-type plants. These findings suggested that ANAC036 and its orthologues are involved in the growth of leaf cells.
"The NAC transcription factors are multifunctional proteins with various roles in plant growth and development, such as maintenance of the shoot apical meristem (Souer et al. 1996; Vroemen et al. 2003), lateral root development (Xie et al. 2000), flower formation (Ishida et al. 2000; Li et al. 2011), plant immune responses (Kaneda et al. 2009), plant organ senescence (Kou et al. 2012), embryo development (Kunieda et al. 2008), cell division (Kim et al. 2006), cell growth (Kato et al. 2010), seed germination (Park et al. 2011), senescence (John et al. 1997; Balazadeh et al. 2010, 2011; Yang et al. 2011; Wu et al. 2012; Lee et al. 2012), and formation of secondary walls (Kubo et al. 2005; Mitsuda et al. 2005, 2007; Zhao et al. 2008; Zhong et al. 2010; Yamaguchi et al. 2011; Li et al. 2012). In addition, NAC TFs were also found to participate in plant responses to different abiotic (Tran et al. 2004; Hu et al. 2006; Nakashima et al. 2007; Zheng et al. 2009; Jeong et al. 2010; Gao et al. 2010; Takasaki et al. 2010; Mao et al. 2012; Ze 0 licourt et al. 2012; Jin et al. 2013b; Sun et al. 2012; Kim et al. 2012) and biotic stress (Xie et al. 1999; Ren et al. 2000; Yoshii et al. 2009). "
[Show abstract][Hide abstract] ABSTRACT: NAM, ATAF, and CUC (NAC) genes are plant-specific transcription factors (TFs) that play key roles in plant growth, development, and stress tolerance. To date, none of the ramie NAC (BnNAC) genes had been identified, even though ramie is one of the most important natural fiber crops. In order to mine the BnNAC TFs and identify their potential function, the search for BnNAC genes against two pools of unigenes de novo assembled from the RNA-seq in our two previous studies was performed, and a total of 32 full-length BnNAC genes were identified in this study. Forty-seven function-known NAC proteins published in other species, in concert with these 32 BnNAC proteins were subjected to phylogenetic analysis, and the result showed that all the 79 NAC proteins can be divided into eight groups (NAC-I-VIII). Among the 32 BnNAC genes, 24, 2, and 1 gene showed higher expression in stem xylem, leaf, and flower, respectively. Furthermore, the expression of 14, 11 and 4 BnNAC genes was regulated by drought, cadmium stress, and infection by root lesion nematode, respectively. Interestingly, there were five BnNAC TFs which showed high homology with the NAC TFs of other species involved in regulating the secondary wall synthesis, and their expressions were not regulated by drought and cadmium stress. These results suggested that the BnNAC family might have a functional diversity. The identification of these 32 full-length BnNAC genes and the characterization of their expression pattern provide a basis for future clarification of their functions in ramie growth and development.
"For example, ATAF2, which is a pathogenesis-related gene in Arabidopsis, showed expression mainly in roots, leaves and mature flowers (Delessert et al. 2005). ANAC036 which caused a dwarf phenotype in Arabidopsis thaliana, was expressed mainly in rosette leaves (Kato et al. 2010). AtNAC2 was expressed mainly in root tissues and involved in salt stress responses and lateral root development (He et al. 2005). "
[Show abstract][Hide abstract] ABSTRACT: NAC (no apical meristem, Arabidopsis transcription activation factor 1 and 2, cup-shaped cotyledon 2) transcription factors (TFs) play important roles in plant growth, development, and responses to abiotic and biotic stress. Two novel NAC TFs were isolated from Citrullus colocynthis, a highly drought-tolerant cucurbit species: CcNAC1 and CcNAC2 each with conserved A–E NAC domains. Subcellular location of CcNAC1 and CcNAC2 investigated via transient expression of 35S::CcNAC1::GFP and 35S::CcNAC2::GFP fusion constructs in Arabidopsis protoplasts, revealed nuclear localization. The transactivation ability of CcNACs was examined in the GAL4 yeast assay system, and showed that only the C-terminal domain of CcNAC1 has the ability to activate reporter genes LacZ and His3. The CcNAC genes accumulated in a tissue-specific manner with expression levels in male flowers of C. colocynthis higher than leaves, hypocotyls or roots. Genome walking was used to isolate the CcNAC1 and CcNAC2-promoter regions. A high number of stress-related sequence motifs were detected, especially in the CcNAC1 promoter. C. colocynthis seedlings were treated with PEG, abscisic acid, salicylic acid (SA), jasmonic acid (JA), H2O2, ethylene, gibberellic acid (GA), wounding or salt. High CcNAC1 expression levels were detected following JA application, and wounding, while high CcNAC2 levels followed treatment with GA, JA, SA, and wounding, indicative of differential regulation of these stress responsive TFs in this cucurbit species.
Acta Physiologiae Plantarum 03/2014; 36(3). DOI:10.1007/s11738-013-1440-5 · 1.58 Impact Factor
"Genes encoding NAC proteins can be regulated (i) transcriptionally by upstream TFs such as ABREs (ABA-responsive elements) and DREs (Dehydration-responsive elements), (ii) post-transcriptionally by micro-RNAs or alternative splicing, and (iii) post-translationally by ubiquitinization, dimerization, phosphorylation or proteolysis . These regulatory steps assists the functional involvement of NAC proteins in majority of plant processes including orchestration of organ, fiber and secondary wall development , –, cell cycle control –, and senescence ,. Their multi-functionality has also been implicated in the regulation of molecular pathways that govern abiotic and biotic stress responses through mediation by hormones , , –. "
[Show abstract][Hide abstract] ABSTRACT: The NAC proteins represent a major plant-specific transcription factor family that has established enormously diverse roles in various plant processes. Aided by the availability of complete genomes, several members of this family have been identified in Arabidopsis, rice, soybean and poplar. However, no comprehensive investigation has been presented for the recently sequenced, naturally stress tolerant crop, Setaria italica (foxtail millet) that is famed as a model crop for bioenergy research. In this study, we identified 147 putative NAC domain-encoding genes from foxtail millet by systematic sequence analysis and physically mapped them onto nine chromosomes. Genomic organization suggested that inter-chromosomal duplications may have been responsible for expansion of this gene family in foxtail millet. Phylogenetically, they were arranged into 11 distinct sub-families (I-XI), with duplicated genes fitting into one cluster and possessing conserved motif compositions. Comparative mapping with other grass species revealed some orthologous relationships and chromosomal rearrangements including duplication, inversion and deletion of genes. The evolutionary significance as duplication and divergence of NAC genes based on their amino acid substitution rates was understood. Expression profiling against various stresses and phytohormones provides novel insights into specific and/or overlapping expression patterns of SiNAC genes, which may be responsible for functional divergence among individual members in this crop. Further, we performed structure modeling and molecular simulation of a stress-responsive protein, SiNAC128, proffering an initial framework for understanding its molecular function. Taken together, this genome-wide identification and expression profiling unlocks new avenues for systematic functional analysis of novel NAC gene family candidates which may be applied for improvising stress adaption in plants.
PLoS ONE 05/2013; 8(5):e64594. DOI:10.1371/journal.pone.0064594 · 3.23 Impact Factor
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