Genomic characterization of the NAC transcription factors in carnation and function analysis of DcNAC41 involved in thermotolerance.

Abstract

As pivotal regulators unique to plants, NAC family extensively orchestrate various life processes ranging from seed germination through growth and development to responses to environmental stresses. This study unraveled 71 NAC TFs in the carnation (Dianthus caryophyllus L.) genome, designated as DcNAC1 to DcNAC71, encoding amino acid sequences ranging from 80 to 718 residues. Subcellular localization predictions revealed a predominance of nuclear localization among these DcNACs. Phylogenetic analysis classified DcNACs into 14 distinct subgroups, each exhibiting similar gene structures and motifs. Promoter analysis highlighted the abundance of cis-regulatory elements (CREs) associated with plant growth and development regulation, hormone signaling, light response, and diverse stress responses, with stress-responsive CREs being the most prevalent, with at least one stress-responsive CRE detected in all DcNAC promoters. To assess their functional roles, 12 DcNACs, were randomly selected from different subgroups for expression profiling under heat, ABA, cold, and salt stress conditions, revealing distinct expression patterns for specific stress types. Notably, DcNAC41, which exhibited marked up-regulation under heat stress, was isolated and subsequently transformed into Arabidopsis. In heat-stressed conditions, transgenic Arabidopsis overexpressing DcNAC41 exhibited significant improvements in growth performance, survival rates, enhanced photosynthetic capacity, and strengthened ROS scavenging abilities. This study offers valuable insights into the comprehensive response of carnation DcNACs towards heat stress, particularly underscoring the potential of DcNAC41 as a promising candidate for enhancing thermotolerance in plants.