Identification and Characterization of Transcription Factors Involved in Geraniol Biosynthesis in Rosa chinensis

Fragrance is an important characteristic of rose flowers and is largely determined by the terpenes. Rose has a unique NUDX1 (NUDIX HYDROLASES 1)–dependent monoterpene geraniol biosynthesis pathway, but little is known about its transcriptional regulation. In this study, we characterized two China rose (Rosa chinensis) materials from the ‘Old Blush’ variety with contrasting aromas. We profiled the volatile metabolome of both materials, and the results revealed that geraniol was the main component that distinguishes the aroma of these two materials. We performed a comparative transcriptome analysis of the two rose materials, from which we identified the hydrolase RcNUDX1 as a key factor affecting geraniol content, as well as 17 transcription factor genes co-expressed with RcNUDX1. We also determined that the transcription factor RcWRKY70 binds to four W–box motifs in the promoter of RcNUDX1, repressing RcNUDX1 expression, based on yeast one-hybrid and transient dual-luciferase assays. These results provide important information concerning the transcriptional regulatory framework underlying the control of geraniol production in rose.