Abstract
The NAC transcription factor (TF) is one of the most significant TFs in plants and is widely involved in plant growth, development, and responses to biotic and abiotic stresses. To date, there are no systematic studies on the NAC family in peanuts. Herein, 132 AhNACs were identified from the genome of cultivated peanut, and they were classified into eight subgroups (I–VIII) based on phylogenetic relationships with Arabidopsis NAC proteins and their conserved motifs. These genes were unevenly scattered on all 20 chromosomes, among which 116 pairs of fragment duplication events and 1 pair of tandem duplications existed. Transcriptome analysis showed that many AhNAC genes responded to drought and abscisic acid (ABA) stresses, especially most of the members in groups IV, VII, and VIII, which were expressed at larger differential levels under polyethylene glycol (PEG) and/or ABA treatment in roots or leaves. Furthermore, 20 of them selected in response to PEG and ABA treatment were evaluated by quantitative real-time polymerase chain reaction. The results showed that these genes significantly responded to drought and ABA in roots and/or leaves. This study was helpful for guiding the functional characterization and improvement of drought-resistant germplasms in peanuts.
Highlights
The NAC transcription factor (TF) is one of the most abundant types of TFs in plants; its designated name comes from the homologous proteins encoded by NAM, ATAF1/ATAF2, and CUC2 (Souer et al, 1996)
Arabidopsis NAC protein sequences were downloaded from the Arabidopsis Information Resource4, and sequence alignment of NAC TFs in peanut and Arabidopsis was performed by the MUSCLE method (Kumar et al, 2016)
A total of 196 NAC sequences were retrieved after searching the peanut protein database using the NAM conserved domain (Pfam: PF02365) by the local HMMER 3.0 software
Summary
The NAC transcription factor (TF) is one of the most abundant types of TFs in plants; its designated name comes from the homologous proteins encoded by NAM, ATAF1/ATAF2, and CUC2 (Souer et al, 1996). NAC TFs have similar N-terminal structures (Aida et al, 1997), which consist of five subdomains (A–E), and usually contain approximately 160 amino acid residues. Subdomains A, C, and D are highly conserved. The C-terminus of the NAC protein contains a transcriptional activation region, which has higher diversity, and some repeated amino acids, such as serine, threonine, and proline, are enriched in this region (Tran et al, 2010; Wang and Dane, 2013; Kim et al, 2016; Mathew and Agarwal, 2018)
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