Genome-wide analysis identifies LliNAC80 as a potential key regulator of abiotic stress resilience in endangered mangrove Lumnitzera littorea

Lumnitzera littorea (Jack) Voigt is a true mangrove species of important ecological and medicinal values; however, it is highly sensitive to environmental fluctuations and is currently endangered in China. Thus, elucidating the molecular mechanisms underlying its stress tolerance is essential not only for its conservation, but also for identifying valuable genetic resources to improve plant resilience to stresses. NAC transcription factors represent a major family involved in regulating plant responses to abiotic stressors. In this study, a total of 84 NAC genes were identified in the L. littorea genome, which were categorized into 16 subfamilies. These genes were unevenly distributed across the 12 chromosomes, with dispersed duplication identified as the primary driver for the expansion of L. littorea NAC (LliNAC) gene family. Comparative transcriptome analysis revealed that 34 LliNAC genes were up-regulated in L. littorea in response to cold stress. Among these, LliNAC80 emerged as a key regulator of the transcriptional remodeling of genes associated with chilling sensing, antioxidation, and osmoprotection. Furthermore, overexpression of LliNAC80 substantially enhanced the tolerance of Arabidopsis thaliana seedlings to low temperature, hyper-salinity, and osmotic stress. These findings highlight the functional importance of LliNAC genes in environmental adaptation of L. littorea, and identify LliNAC80 as a promising candidate for future bioengineering-based improvement of stress resilience in mangroves and crops.