| Carotenoid has very important functions in plants and some colored carotenoids are the main source of pigment of lots of flowers and fruits. Carotenoids are mainly related with yellow, orange, and etc. Rape flower is usually yellow, and the white flower of rape has an important theoretical research and practical application value. In this study16rape strains of different colors were used as research materials, the carotenoids in petals of different colors were determined with high-performance liquid chromatography (HPLC) and the relationship between rape petal color and carotenoid content was preliminary analyzed. At the same time, the white-flowered resynthesized B.napus line’HW243’, yellow flower B.napus cultivar Zhongyou821and their hybrid F1(HW243x Zhongyou821)-pale yellow flower as the materials for analyze the carotenoids content and expression of carotenogenic genes in Brassica napus plant petals by HPLC and RT-PCR. The main results were summarized as the follows:1. The carotenoids content in rapeseed flowers of different colorsIn order to explore the relationship between carotenoid contents and colors,16rapeseed lines with4colors were selected in this study, and the contents of xanthophyll, beta-carotene and lycopene in the petals were determined respectively by HPLC and analyzed. The results shows, the compositions and content of carotenoids were similar in petals among the rapeseed lines of same color; the compositions and content of carotenoids were obvios differences in petals among the rapeseed lines of different colors. First, the contents of xanthophyll, beta-carotene and lycopene in the white petals were similar. Second, the contents of xanthophyll, beta-carotene and lycopene in the petals of same color (except white) were obvios defference, the petals contains more Lycopene than other carotenoids. Third, among the different materials of different colors, as the color changes (white petals——pale yellow petals——yellow petals——golden yellow petals) the content of carotenoids were increased especially for the lycopene. The results initially suggest that carotenoids are important factors that affect the color of rapeseed petals, and maybe the content of lycopene is the major factor to affect the color of rapeseed petals.2. Changes of carotenoids during petal developmentThe carotenoids content in petals of different petal development stages were determined by HPLC, it shows that the stage2of the petal development was a turning point, and in all materials showed the same phenomena:the contents of xanthophyll and P-carotenoid were severely decreasing and the content of Lycopene was sharp rised up to its maximum content in this period. At the same development stage, among the materials of defferent colors, as the color changes (white petals——pale yellow petals——yellow petals) the content of carotenoids were increased especially for the lycopene. The difference of xanthophyll conten was smallest, of which the maximum difference value between yellow petals and white petals was about11μg/g FW. The difference of β-carotenoid conten was second, of which the maximum difference value between yellow petals and white petals was about43μg/g FW. The difference of Lycopene conten was the biggest, of which the maximum difference value between yellow petals and white petals was about190μg/g FW; The Lycopene contents in yellow petals of all stages were more than100μg/g FW and that in white petals of all stages were less than10μg/g FW.3. Expression of BnPSY and BnLYCE gene in Brassica napu plant petalsThe expression of BnPSY gene shows that the relative expression level was highest in yellow petals and in white petals the relative expression level was lowest. In the yellow petals of Zhongyou821, in the early stage the relative expression of BnPSY gene was up to its maximum and keeped high levels in the following stages. In the pale yellow petals of F1, in the early stage the relative expression of BnPSY gene was up to its maximum and decreased in the following stages, but still higher than which in white petals. But in the white flowers of HW243, the relative expression of BnPSY gene was up to its maximum in the stage3(not the early stage1) and decreased in the following stages. Although it’s the maximum relative expression level of white petals of HW243at stage3, it’s obvios lower than yellow petals of Zhongyou821and pale-yellow flowers of F1.The expression of BnLYCE gene shows that, in the yellow petals of Zhongyou821, in the early stage (stage1) the relative expression of BnLYCE gene was up to its maximum and decreased in the following stages, and from stagel to stage4its expression levels were lower than that in white petals of HW243. In the white petals of HW243and pale yellow petals of F1, the relative expression of BnLYCE gene was up to its maximum in the early stage and sharp decreased in the following stages.Linked the relative expression of the two genes, it can easily find that in the yellow petals of Zhongyou821its BnPSY gene keeped high expression levels, which was1000folds than the control and100fold than that in white flowers (Fig.3-13). From this, we can see that the biosynthesis of lycopene in yellow petals was much higher than that in white petals. On the other hand, the expression levels of BnLYCE gene in yellow petals of Zhongyou821were lower than that in white petals of HW243. From this, we can see that the decomposition and transformation of lycopene in yellow petals was lower than that in white petals. For these factors, the synthesis of lycopene was high and transformantion was low in yellow petals, which made the lycopene contene at high level in yellow petals; but in the white petals, the synthesis of lycopene was low and transformantion was high, which made the lycopene contene at low level; so, the content of lycopene in yellow petals are much more than that in white petals (Fig.3-8, table3-9).And the difference of Lycopene content was the biggest, from this it can be conclude that lycopene was the major factor to affect the color of petals in Brassica napus. |
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