| Floral fragrance is one of the important values of ornamental plants. Also, it is an essential factor with important aesthetic and economic values in the application of gardening. Floral composition analysis is a hot research field at home and abroad in recent years. Unfortunately, many ornamental plants gradually lost their fragrance in the long-term breeding process. Floral scent analysis can be so hard to break through due to the complexity of the floral metabolism. Primula forbesii Franch. which are only found in China and has a long flowering period, a great number of flowers, a strong scent and a high ornamental value. These characters made P. forbesii quite rare in primulaceae.In this paper, we selected a proper floral scent collecting methods for P. forbesii through a comparison of different floral sampling methods. And we used the suitable collecting method combine with GC-MS to test floral scent compositoins and rhythmic changes of P. forbesii in different stages and morphs. Additionally, we observed the fragrance release sites. The main results are as follows:1. The most suitable collecting method was selected through the comparison of 3 different methods. Solid phase micro extraction (SPME) (75μm CAR/PDMS and 100μm PDMS as extraction head), thermal desorption (ATD) (Tenax GR adsorbent) and Purge&trap (P&T) combined with gas Chromatograph-Mass Spectrometer-computer (GC-MS) were aim to analysize the floral compositions of P. forbesii. From the result, we found that Purge&trap can get the maximum number of floral scent compositions and can be more accurate.2. Floral scent compositions of 3 different flowering stages were analysized by P&T. From the result that analyzed by dynamic headspace we can tell that linalool is the most important floral volatiles, which has a content that up to 45.08%, methyl salicylate and terpineol are also the main aromatic components. In addition, during the 3 stages of the flowers, monoterpene showed a low-high-low trend; phenyl/phenylpropanoid increased smoothly; content of ester in fatty acid derivatives reached the maximum value in the late flowering stage. Alcohols showed a high-low-high trend.3. Floral scent compositions of 2 different morphs of P.forbesii were analysized by P&T.23 compounds were detected from pin flowers,31 from thrum flowers and 8 kind of fatty acid derivatives more in thrum group. In pin group,73.25% of terpenes was detected, while, thrum group has a lower content of terpenes, only 57.76%.4. Using Neutral red dye absorption method and environmental scanning electron microscope to observe all parts of petals, buds and torus of P.forbesii. Found that their epidermal cells are formed bulge onto the surface or just glands. We assert that the flower petals, stamens and the base of ovary can release flowers fragrant volatile.In this paper, through the research of the floral scent composition in differrent morphs, release rhythm and release site of P.forbesii, we have more in-depth understanding of floral scent theory, providing a theoretical basis for further understanding of the key enzymes of biosynthetic pathway and floral genes that involved in the metabolism. Also, lay a foundation to effectively change the aromatic quality of Primula and enhance ornamental values of this category. |
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