Genome-wide analysis of NAC gene family and function exploration of SaNAC30 in Santalum album L.

The NAC (NAM, ATAF1/2, and CUC2) transcription factors (TFs) constitute one of the largest families of TFs and serve as pivotal regulators in growth and the synthesis of secondary metabolites. Santalum album L., commonly known as sandalwood, is an economically significant tree species renowned for its essential oil in heartwood, which primarily comprises terpenoids. Although significant advancements have been made in elucidating the biosynthetic pathway of these invaluable metabolites, the transcriptional regulation governing this process remains largely unexplored. To investigate the role of NAC TFs in terpenoid production, we conducted a comprehensive genome-wide analysis of the NAC gene family in sandalwood, resulting in the identification of 57 SaNAC genes that could be categorized into eight subfamilies. Subsequent analyses focused on the molecular characteristics of these genes, including their gene structure, promoter cis-elements, and expression profiles. RNA-seq analysis revealed that SaNAC30 exhibits a distinctive expression pattern specifically in the transition zone of S. album. We then isolated SaNAC30 from sandalwood and employed yeast one-hybrid and dual-luciferase assays and demonstrated that SaNAC30 physically interacts with the promoter of the terpenoid biosynthesis gene SaMVK. Overexpression of SaNAC30 in sandalwood calli led to an increase in SaMVK expression and essential oil contents. Our findings suggest that SaNAC30 functions as a key regulator of terpenoid biosynthesis in S. album and opens avenues for the application of genetic engineering strategies aimed at augmenting heartwood and essential oil yields in this economically crucial species.