Changes in volatile organic compounds and differential expression of aroma-related genes during flowering of Rosa rugosa ‘Shanxian’

Abstract

Rosa rugosa ‘Shanxian’, a local variety of rose in Shandong Province, was studied for its aroma characteristics, including changes in aroma components and differential expression of aroma-related genes during flowering. The volatiles emitted from flowers were collected by headspace solid-phase microextraction and analyzed by gas chromatography–mass spectrometry at the budding stage, the early, half and full opening stages, and the withering stage. Sixty-six compounds were identified, and the full opening stage contained the highest level of every single aroma component compared with the other four stages. The major constituents of R. rugosa ‘Shanxian’ were alcohols, esters, ketones, aldehydes, phenols, and terpenes, with alcohols being the most abundant. The aroma of R. rugosa ‘Shanxian’ was mainly characterized by rich fruit aromas, floral aromas, and soft plant aromas. RrAAT, RrDXR, and RrDXS genes played a key role in monoterpene biosynthesis in R. rugosa ‘Shanxian’. The temporal and spatial expression of RrAAT, RrDXR, and RrDXS were measured at different flower developmental stages. Among the three genes, the overall expression level of RrAAT was significantly higher than that of RrDXR and RrDXS and was associated with the accumulation of acetate esters in R. rugosa, which could be used as an important candidate gene for rose metabolism. Taken together, our results demonstrated that R. rugosa ‘Shanxian’ has better aromatic characteristics than R. rugosa ‘Fenghua’. With a particularly prominent aroma that is strong and sweet, ‘Shanxian’ should be further investigated as a valuable breeding material that could be used to enhance genetic diversity and develop new rose varieties.