Isolation of genes determining the flower color traits in Asiatic hybrid lily and their characterization by RNAi

由于亚洲百合花被片中花色素苷的形成受单基因控制，而花色素苷合成基因在花被片中协调表达，因此可能有转录因子调控花色素苷的形成。在本研究中，LhbHLH 1和LhbHLH 2两个基因被分离，这两个基因分别与PhJAF 13和PhAN 1具有同源性。LhbHLH 1和LhbHLH 2在花被片和叶片中表达。百合芽在光照下，花青苷色素在叶片中积累，光照8天后花青苷色素几乎消失。LhbHLH 2的表达受光照的强烈影响，在光照后2天达到峰值，之后下降。这种表达变化与花青苷含量的变化几乎是平行的。在花被片中观察到类似的结果，即黑暗处理降低了花青苷含量和LhbHLH 2表达。这些结果表明，两个bHLH基因，特别是LhbHLH 2， ...更多信息 与花青苷的生物合成有关。接下来，分析类胡萝卜素组成和编码类胡萝卜素生物合成酶的基因的表达。黄色花瓣中主要为花药黄质、9 Z-紫黄质、顺式叶黄素和紫黄质，红色花瓣中主要为辣椒素。黄色和红色花品种的花被片类胡萝卜素的积累增加，而类胡萝卜素的含量下降，在那些白色和粉红色花品种。分离类胡萝卜素生物合成基因PSY、PDS、ZDS、CRTISO、LCYB、HYB和LCYE并检测其表达。PSY、PDS、ZDS、CRTISO和HYB基因的转录量随着花被片的生长而增加，在花被片长6-7 cm时达到高峰。相反，在花被片发育过程中，LCYB和LCYE的转录分别保持不变和下降。这些基因的转录模式在黄色、红色、粉红色和白色色花被片中基本相同，但类胡萝卜素含量差异很大，表明类胡萝卜素在花被片中的积累不是由生物合成基因的转录决定的。少

Because anthocyanin pigmentation in tepals of Asiatic hybrid lily is controlled by a single dominant gene and anthocyanin biosynthetic genes are expressed coordinately in tepals, some transcription factor is expected to control the presence or absence of anthocyanin pigment. In this study, two genes, LhbHLH1 and LhbHLH2 were isolated, which had homologies with PhJAF13 and PhAN1, respectively. LhbHLH1 and LhbHLH2 were expressed in tepals and leaves. When lily buds were exposed to light, anthocyanin pigment accumulated in leaves, which nearly disappeared 8 days after light exposure. Expression of LhbHLH2 was strongly affected by light, which peaked at 2 days after light exposure and decreased after that. This expressional change was nearly parallel with the change of anthocyanin content. Similar result was observed in tepals, that is, both anthocyanin content and LhbHLH2 expression were decreased by the dark treatment. These results suggest that the two bHLH genes, especially LhbHLH2, ar … More e correlating to anthocyanin biosynthesis. Next, carotenoid composition and the expression of genes encoding carotenoid biosynthetic enzymes were analyzed. Most of the carotenoids in yellow petals were antheraxanthin, 9Z-violaxanthin, cis-lutein and violaxanthin, and the major carotenoid in red petal was capsantin. Tepals of yellow and red flowered cultivars showed increased accumulation of carotenoids, whereas carotenoid content was decreased in those of white and pink flowered cultivars. Carotenoid biosynthesizing genes, PSY, PDS, ZDS, CRTISO, LCYB, HYB and LCYE, were isolated and their expression was examined. Transcription of PSY, PDS, ZDS, CRTISO, and HYB increased as tepals grew and peaked at the 6-7 cm tepal-length stage. On the contrary, transcription of LCYB and LCYE were constant and decreased, respectively, during tepal development. Transcription patterns of these genes were basically the same among yellow, red, pink and white colored tepals although carotenoid contents were very different among them, indicating that carotenoid accumulation in tepals is not explained by the transcription of biosynthetic genes. Less