Identification Of Volatile Aroma Compounds Of Toona Sinensis (A. Juss) Roem Buds And Investigation Of Genes Expression Profiles Confering Aroma Production

Aroma is one of the important indexes of Toona sinensis (A. Juss) Roem quality that also determines its edible and commercial value. To detect the existing compounds of volatile aroma and related biosynthetic genes that the variety 'Heiyouchun' (named THToa) originated in the county of Taihe (Province of Chinese Anhui), confer aroma training in Toona sinensis was studied. By using the headspace solid-phase micro extraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) methods, the chemical composition and relative content were analyzed. The gene expression of key enzymes including terpene synthase (TsTPS), farnesyl diphosphate synthase (TsFPS), 1-deoxy-d-ribulose 5-phosphate synthase (TsDXS), 3-hydroxy-3methylglutaryl-coenzyme A reductase (TsHMGR) and two important regulators, TsAP2/ERF and TsWRKY, were also detected by real-time PCR (RT-PCR) at different developmental periods of leaves. The results showed that a total of 24 compounds were detected from the volatile oil of buds of THToa, which were mainly terpenes, esters, alcohols, ethers, aldehydes and thiophenes. Among them, alpha-caryophyllene (8.521%) was the most abundant, followed by prop-l-enyldithiopro (8.214%), 1-propyl-2-(4thiohepth) (7.155%), aromadendrene (5.106%) and gamma-elemene (6.928%). TsDXS, TsHMGR1, TsTPS, TsAP2 and TsWRKY47 showed first low expression, then elevated and then decreased, while TsFPS2 showed early high expression during leaf growth and then gradually decreased tendency. It was speculated that the differential expression of these key genes during the growth of Toona sinensis leaves was closely related to the synthesis of aroma components. The results of this study may provide a foundation for elucidating the formation mechanism of Toona aroma, evaluating the quality of buds, as well as facilitating the molecular assisted breeding and development and utilization of Toona Sinensis.