Department of Life Sciences, National University of Kaohsiung, Kaohsiung 811, Taiwan.
Plant Cell Rep. 2011 Jun;30(6):1007-17. doi: 10.1007/s00299-011-1006-1. Epub 2011 Jan 28.
Anthocyanin is the primary pigment contributing to red, violet, and blue flower color formation. The solubility of anthocyanins is enhanced by UDP glucose: flavonoid 3-O-glucosyltransferase (UFGT) through transfer of the glucosyl moiety from UDP-glucose to 3-hydroxyl group to produce the first stable pigments. To assess the possibility that UFGT is involved in the flower color formation in Phalaenopsis, the transcriptional activities of PeUFGT3, and other flower color-related genes in developing red or white flower buds were examined using RT-PCR analysis. In contrast with chalcone synthase, chalcone isomerase, and anthocyanidin synthase genes, PeUFGT3 transcriptional activity was higher expressed in the red color of Phalaenopsis cultivars. In the red labellum of Phalaenopsis 'Luchia Lady', PeUFGT3 also showed higher expression levels than that in the white perianth. PeUFGT3 was predominantly expressed in the red region of flower among various Phalaenopsis cultivars. To investigate the role of PeUFGT3 in red flower color formation, PeUFGT3 was specifically knocked down using RNA interference technology via virus inducing gene silencing in Phalaenopsis. The PeUFGT3-suppressed Phalaenopsis exhibited various levels of flower color fading that was well correlated with the extent of reduced level of PeUFGT3 transcriptional activity. Furthermore, there was a significant decrease in anthocyanin content in the PeUFGT3-suppressed Phalaenopsis flowers. The decrease of anthocyanin content due to PeUFGT3 gene silencing possibly caused the faded flower color in PeUFGT3-suppressed Phalaenopsis. Consequently, these results suggested that the glycosylation-related gene PeUFGT3 plays a critical role in red color formation in Phalaenopsis.
花色素苷是使花朵呈现红色、紫色和蓝色的主要色素。UDP 葡萄糖：类黄酮 3-O-葡萄糖基转移酶（UFGT）通过将葡萄糖基从 UDP-葡萄糖转移到 3-羟基来增强花色素苷的溶解性，从而产生第一个稳定的色素。为了评估 UFGT 是否参与蝴蝶兰花朵颜色的形成，使用 RT-PCR 分析检测了发育中的红色或白色花蕾中 PeUFGT3 和其他与花色相关基因的转录活性。与查尔酮合酶、查尔酮异构酶和花青素合酶基因相比，PeUFGT3 的转录活性在蝴蝶兰品种的红色中表达更高。在蝴蝶兰“Luchia Lady”的红色唇瓣中，PeUFGT3 的表达水平也高于白色花瓣。PeUFGT3 在各种蝴蝶兰品种的红色区域中表现出更高的表达水平。为了研究 PeUFGT3 在红色花朵颜色形成中的作用，通过病毒诱导基因沉默技术特异性敲低了 PeUFGT3 在蝴蝶兰中的表达。PeUFGT3 被抑制的蝴蝶兰表现出不同程度的花色褪色，这与 PeUFGT3 转录活性降低的程度密切相关。此外，PeUFGT3 被抑制的蝴蝶兰花中花色素苷含量显著降低。由于 PeUFGT3 基因沉默导致花色素苷含量降低，可能导致 PeUFGT3 被抑制的蝴蝶兰花色褪色。因此，这些结果表明，糖基化相关基因 PeUFGT3 在蝴蝶兰的红色形成中起关键作用。
