Comparative Genomics of NAC Transcriptional Factors in Angiosperms: Implications for the Adaptation and Diversification of Flowering Plants

Abstract

NAC proteins constitute one of the largest groups of plant-specific transcription factors and are known to play essential roles in various developmental processes. They are also important in plant responses to stresses such as drought, soil salinity, cold, and heat, which adversely affect growth. The current knowledge regarding the distribution of NAC proteins in plant lineages comes from relatively small samplings from the available data. In the present study, we broadened the number of plant species containing the NAC family origin and evolution to shed new light on the evolutionary history of this family in angiosperms. A comparative genome analysis was performed on 24 land plant species, and NAC ortholog groups were identified by means of bidirectional BLAST hits. Large NAC gene families are found in those species that have experienced more whole-genome duplication events, pointing to an expansion of the NAC family with divergent functions in flowering plants. A total of 3,187 NAC transcription factors that clustered into six major groups were used in the phylogenetic analysis. Many orthologous groups were found in the monocot and eudicot lineages, but only five orthologous groups were found between P. patens and each representative taxa of flowering plants. These groups were called basal orthologous groups and likely expanded into more recent taxa to cope with their environmental needs. This analysis on the angiosperm NAC family represents an effort to grasp the evolutionary and functional diversity within this gene family while providing a basis for further functional research on vascular plant gene families.

Control of root cap maturation and cell detachment by BEARSKIN transcription factors in Arabidopsis

“…SMB, BRN1 and BRN2 regulate a broad range of subcellular events associated with root cap differentiation SMB, BRN1 and BRN2 constitute the group I NAC transcription factors together with the VND and NST/SND members that control SCW synthesis in vascular cells (Pereira-Santana et al, 2015). Based on the finding that SMB, BRN1 and BRN2 activate SCW synthesis in the root vasculature (as do the VND proteins), group I NAC proteins appear to possess a shared activation capacity for SCW synthesis (Bennett et al, 2010).…”

“…These root cap-like epidermal cells were eventually lost in the differentiation zone, possibly via programmed cell death (Waki et al, 2013). SMB belongs to the group I NAC transcription factors (Pereira-Santana et al, 2015). In Arabidopsis, group I NAC transcription factors also include VND/NST/SND proteins, which are known to promote secondary cell wall (SCW) synthesis in vascular cells, and the two BEARSKIN (BRN) transcription factors, BRN1 and BRN2.…”

Three Rice NAC Transcription Factors Heteromerize and Are Associated with Seed Size

“…Each plant genome has multiple encoding members, with 117 and 151 genes in Arabidopsis and rice, respectively (Nuruzzaman et al, 2010), and similar numbers in other species as well (Pereira-Santana et al, 2015). They have a conserved NAC domain of about 150 amino acids followed by a diversified transcriptional regulatory region (TRR).…”

May the Fittest Protein Evolve: Favoring the Plant‐Specific Origin and Expansion of NAC Transcription Factors

“…According to the most recent phylogenetic classification by Pereira-Santana et al, [18] NAC proteins from green plants cluster into six major groups (Group I-VI). Group Iproposed as the basal NAC groupconsists of TFs essentially serving water conducting and cell supporting functions.…”

“…They are expressed in most tissues and influenced by a range of environmental factors. [17][18][19] Our review focuses on the inherent properties of NACs that might have favored their plant-specific evolution. Several members play significant roles in development and/or stress responses in various plant species.…”