NAC Family Transcription Factors in Tobacco and Their Potential Role in Regulating Leaf Senescence

Abstract

The NAC family is one of the largest families of plant-specific transcription factors (TFs) and NAC proteins play important regulatory roles in a variety of developmental and stress response processes in plants. Members of the NAC family TFs have been shown to be important regulators of leaf senescence in a number of plant species. Here we report the identification of the NAC family in tobacco (Nicotiana tabacum) and characterization of the potential role of some of the tobacco NAC TFs in regulating leaf senescence. A total of 154 NAC genes (NtNACs) were identified and clustered together with the Arabidopsis NAC family into fifteen groups (a-o). Transcriptome data analysis followed by qRT-PCR validation showed that the majority of the senescence-up-regulated NtNACs fall into subgroups NAC-b and f. A number of known senescence regulators from Arabidopsis also belong to these two subgroups. Among these senescence-up-regulated NtNACs, NtNAC080, a close homolog of AtNAP, is a positive regulator of leaf senescence. Overexpression of NtNAC080 caused early senescence in Arabidopsis leaves and NtNAC080 mutation induced by Cas9/gRNA in tobacco led to delayed leaf senescence.

Identification and Expression of NAC Transcription Factors of Vaccinium corymbosum L. in Response to Drought Stress

“…Moreover, conserved motifs of DEGs were predicted using MEME program and 10 motifs, named motif 1-10 ( Figure S2) were defined in these 62 NAC proteins (Figure 5a). As expected, all of the conserved motifs were located at the N-terminal of the NAC protein, which is consistent with the highly conserved DNA-binding domain of the N-terminal of NAC protein, as described previously [11,38]. In contrast to N-terminal, there was no conserved motif in the C-terminal of NAC protein, which is a variable transcriptional regulation region.…”

“…Venn diagrams of DEGs were analyzed by Majorbio Cloud Platform. Heatmap was generated on the basis of the log 10 fold-change values at MD_L (leaf of moderate drought stress treatment group)/SD_L (leaf of severe drought stress treatment group)/MD_R (root of moderate drought stress treatment group)/SD_R (root of severe drought stress treatment group) when compared with CK_L (leaf of control group) and CK_R (root of control group) [11]. The phylogenetic analysis of DEGs was the same as above.…”

“…To examine the phylogenetic relationship among VcNAC proteins, an unrooted phylogenetic tree was constructed with alignments of 158 VcNACs and 51 AtNACs. According to the structural similarity and conserved motifs, all of the NAC proteins were divided into 14 subgroups [11,35]. We found that…”

“…The conserved NAM domain could be divided into five subdomains (A-E): subdomain A is probably involved in the formation of dimerization; subdomain C and D are relatively conserved, which may be related to DNA binding; whereas subdomain B and E are more variable, and determine the function of different NAC proteins. The highly diverse transcription regulatory region at the C-terminal of NAC proteins confers transcriptional activation diversity of different NAC TFs [11,12]. NAC TFs have been reported to participate in various biological processes in plants, such as formation of second cell wall, programmed cell death and flowering period of plant [13][14][15].…”

Genomic prediction and quantitative trait locus discovery in a cassava training population constructed from multiple breeding stages

“…This gene is known to encode for a protein kinase. Overexpression of a similar gene in tobacco (Nicotiana tabacum L.) stimulated plant defense responses (Li et al, 2018). Similarly, the region on chromosome 9, with a significant marker S9_10707044, contains a single gene (Manes.09G074200.1) that encodes a kinase family protein.…”