Structural, evolutionary and functional analysis of the NAC domain protein family in Eucalyptus.
NAC domain transcription factors regulate many developmental processes and stress responses in plants and vary widely in number and family structure. We analysed the characteristics and evolution of the NAC gene family of Eucalyptus grandis, a fast-growing forest tree in the rosid order Myrtales. NAC domain genes identified in the E. grandis genome were subjected to amino acid sequence, phylogenetic and motif analyses. Transcript abundance in developing tissues and abiotic stress conditions in E. grandis and E. globulus was quantified using RNA-seq and reverse transcription quantitative PCR (RT-qPCR). One hundred and eighty-nine E. grandis NAC (EgrNAC) proteins, arranged into 22 subfamilies, are extensively duplicated in subfamilies associated with stress response. Most EgrNAC genes form tandem duplicate arrays that frequently carry signatures of purifying selection. Sixteen amino acid motifs were identified in EgrNAC proteins, eight of which are enriched in, or unique to, Eucalyptus. New candidates for the regulation of normal and tension wood development and cold responses were identified. This first description of a Myrtales NAC domain family reveals an unique history of tandem duplication in stress-related subfamilies that has likely contributed to the adaptation of eucalypts to the challenging Australian environment. Several new candidates for the regulation of stress, wood formation and tree-specific development are reported.
Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), Genomics Research Institute (GRI), University of Pretoria, Private Bag X20, Pretoria, 0028, South Africa.
Steven G
SG
Hussey
Laboratoire de Recherche en Sciences Végétales (LRSV), Université Toulouse, UPS, CNRS, BP 42617, F-31326, Castanet-Tolosan, France.
Mohammed N
MN
Saïdi
Department of Botany, University of British Columbia, 3529-6270 University Blvd, Vancouver, BC, Canada, V6T 1Z4.
Charles A
CA
Hefer
Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), Genomics Research Institute (GRI), University of Pretoria, Private Bag X20, Pretoria, 0028, South Africa.
Alexander A
AA
Myburg
Laboratoire de Recherche en Sciences Végétales (LRSV), Université Toulouse, UPS, CNRS, BP 42617, F-31326, Castanet-Tolosan, France.
Jacqueline
J
Grima-Pettenati
D020816:Amino Acid Motifs; D032461:Chromosomes, Plant / Q000235:genetics; D017124:Conserved Sequence; D005052:Eucalyptus / Q000235:genetics*; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D016013:Likelihood Functions; D005810:Multigene Family; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics*; D017434:Protein Structure, Tertiary
D010940:Plant Proteins
Eucalyptus; NAC; evolution; stress; transcription factor; wood formation