Genome-Wide Identification of NAC Gene Family and Their Correlation Analysis with Sugar Metabolism in Wolfberry (Lycium barbarum L.)

The NAM, ATAF, and CUC (NAC) transcription factors represent a major class of plant-specific transcription factors that regulate plant growth, development, and responses to various biotic and abiotic stresses. Despite their importance, limited information exists about this gene family in wolfberry (Lycium barbarum), a valuable traditional Chinese medicinal plant widely cultivated in northwest China. In this study, 107 LbaNAC genes were identified from the wolfberry genome and found to be unevenly distributed across 12 chromosomes. These LbaNAC genes were clustered into 18 subfamilies, with motif composition and gene structure showing high consistency with their phylogenetic relationships. A total of 192 orthologous gene pairs were identified between wolfberry and tomato, potato, Arabidopsis thaliana, and rice, respectively. Gene duplication analysis revealed that dispersed duplication was a major driver in the expansion of the LbaNAC gene family, while the analysis of the nonsynonymous (Ka) to synonymous (Ks) substitution rates confirmed that purifying selection has been the predominant evolutionary force acting on these genes. Cis-acting element analysis showed that their promoters harbor elements associated with growth, metabolism, and various stress responses. Furthermore, correlation analysis demonstrated that the expression profiles of LbaNAC001, 027, 043, 051, 053, and 080 were significantly and positively correlated with the dynamic changes in glucose, fructose, and sucrose contents in wolfberry fruits. Furthermore, quantitative real-time PCR validation of the selected LbaNAC genes confirmed that their expression patterns were consistent with the transcriptome data. Subcellular localization and transcriptional activation analyses revealed that LbaNAC027 is a nucleus-localized transcriptional activator. This study identifies potential LbaNACs involved in wolfberry fruit sugar metabolism, providing a theoretical foundation for elucidating their regulatory mechanisms.