Project description:Elymus sibiricus L. is a perennial grass of high pastoral and ecological value, playing a critial role in to livestock production and ecological restoration on the Qinghai-Tibet Plateau. NAC transcription factors are crucial regulators of plant development and abiotic stress responses, yet they remain uncharacterized in E. sibiricus. Here, we report the first genome-wide analysis of the NAC family in this allohexaploid species, and identified 290 EsNAC genes. These genes are classified into 14 subfamilies, 11 of which have undergone significant expansion mainly through segmental duplication events, suggesting a potential genetic basis for adaptation to plateau environments. We revealed a pronounced enrichment of light-responsive cis-elements in the promoters of these genes. Further analysis in Arabidopsis showed significant overlap between AtNAC and a set of light-repressed genes, strongly implicating the NAC family in light inhibition pathways. Notably, heterologous overexpression of EsANAC029 (an ortholog of Arabidopsis AtANAC029) in Arabidopsis recapitulated a clear light-inhibition phenotype, including chlorosis and dwarfism. Transcriptomic profiling indicated that EsANAC029 represses the expression of chlorophyll biosynthesis and photosynthesis-related genes, thereby reducing chlorophyll accumulation, impairing photosynthetic capacity, and ultimately leading to growth retardation. In addition, EsANAC029 upregulates genes associated with defense-related pathways, linking light perception with stress adaptation. This work identifies EsANAC029 as a key negative regulator of photosynthesis, likely serving as an integrative node that connects light perception with stress adaptation.
