AUTHOR=Zeng Xiangling , Liu Cai , Zheng Riru , Cai Xuan , Luo Jing , Zou Jingjing , Wang Caiyun 

TITLE=Emission and Accumulation of Monoterpene and the Key Terpene Synthase (TPS) Associated with Monoterpene Biosynthesis in Osmanthus fragrans Lour

JOURNAL=Frontiers in Plant Science

VOLUME=6

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2015.01232

DOI=10.3389/fpls.2015.01232

ISSN=1664-462X

ABSTRACT=<p><italic>Osmanthus fragrans</italic> is an ornamental and economically important plant known for its magnificent aroma, and the most important aroma-active compounds in flowers are monoterpenes, mainly β-ocimene, linalool and linalool derivatives. To understand the molecular mechanism of monoterpene production, we analyzed the emission and accumulation patterns of these compounds and the transcript levels of the genes involved in their biosynthesis in two <italic>O. fragrans</italic> cultivars during flowering stages. The results showed that both emission and accumulation of monoterpenes varied with flower development and glycosylation had an important impact on floral linalool emission during this process. Gene expression demonstrated that the transcript levels of terpene synthase (<italic>TPS</italic>) genes probably played a key role in monoterpene production, compared to the genes in the MEP pathway. Phylogenetic analysis showed that <italic>Of</italic>TPS1 and <italic>Of</italic>TPS2 belonged to a TPS-g subfamily, and <italic>Of</italic>TPS3 and <italic>Of</italic>TPS4 clustered into a TPS-b subfamily. Their transient and stable expression in tobacco leaves suggested that <italic>Of</italic>TPS1 and <italic>Of</italic>TPS2 exclusively produced β-linalool, and <italic>trans</italic>-β-ocimene was the sole product from <italic>Of</italic>TPS3, while <italic>Of</italic>TPS4, a predictive sesquiterpene synthase, produced α-farnesene. These results indicate that <italic>OfTPS1</italic>, <italic>OfTPS2</italic>, and <italic>OfTPS3</italic> could account for the major floral monoterpenes, linalool and <italic>trans</italic>-β-ocimene, produced in <italic>O. fragrans</italic> flowers.</p>