Isolation of 2-phenylethanol biosynthesis related genes and their relationship with 2-phenylethanol accumulation in <Emphasis Type="Italic">Rosa rugosa</Emphasis>

Rosa rugosa is a famous traditional flower in China used not only as a landscape plant but also as a time-honored and valuable aromatic plant. The natural aromatic substance 2-phenylethanol is the major indispensable ingredient of rose flower and rose essential oil. This study adopted R. rugosa ‘Tanghong’ as a test material to isolate 2-phenylethanol biosynthesis related genes RrAADC and RrPAR. The temporal and spatial expression patterns of the two genes in different flower developmental stages and floral organ parts were measured, and the relationship of 2-phenylethanol accumulation to RrAADC and RrPAR expression in R. rugosa was determined. The content of 2-phenylethanol in R. rugosa gradually increased with the degree of flower opening and peaked at the withering stage. The expression level of RrAADC gradually decreased with the degree of flower opening. Meanwhile, the expression level of RrPAR gradually increased from the budding stage to the half opening stage, rapidly decreased at the full opening stage, and slightly increased again toward the withering stage. The content of 2-phenylethanol was the highest in the petals, followed by that in the stamens and pistils. However, this compound was not detected in other parts of the fully opened flower. The expression level of RrAADC peaked in the stamens but was relatively low in the other parts. The expression level of RrPAR was the highest in the stamens and calyxes, followed by that in the pistils and receptacles, and the lowest in the petals and stalks. These results suggest that RrAADC and RrPAR coordinately regulate the biological synthesis of 2-phenylethanol in R. rugosa.     

Pistil abortion in Japanese apricot (<Emphasis Type="Italic">Prunus mume</Emphasis> Sieb. et Zucc.): isolation and functional analysis of <Emphasis Type="Italic">PmCCoAOMT</Emphasis> gene

The abnormal pistils widely occur in Japanese apricot (Prunus mume Sieb. et Zucc) and seriously affect the fruit production. In this study, a CCoAOMT homologue, PmCCoAOMT, was cloned in Japanese apricot and the bioinformatics software analyzed the structural characteristics. The PmCCoAOMT protein was detected to be located in the cell cytoplasm by onion transient expression experiment. Analysis of the real-time PCR data showed that PmCCoAOMT gene expressed in the prophase development of pistil and the expression level in ‘Daqiandi’ was higher than ‘Longyan.’ The expression level in ‘Longyan’ was higher than ‘Daqiandi’ in the late period development of pistil, and the expression level of perfect flower (perfect pistil) was higher than imperfect flower (pistil deformity and no pistil). Compared with the control, the over-expression of PmCCoAOMT transgenic tobacco lines showed bigger flowers, darker petals. The lignin monomer composition in transgenic tobacco lines was also measured, and the results showed that transgenic tobacco lines had a higher S (Syringyl)/G (Guaiacyl) ratio (22.3 %) than control lines (11.8 %). Also, the perfect flower buds contained more S/G ratio (92.62 %) than imperfect flower buds (83.55 %) in ‘Daqiandi.’ Our results indicated that the PmCCoAOMT gene might have function in lignin accumulation, which contributed to pistil development in Japanese apricot.