Alberta Innovates Phytola Centre, Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada T6G 2P5.
Plant Physiol. 2012 Oct;160(2):978-89. doi: 10.1104/pp.112.198713. Epub 2012 Jul 30.
Transparent Testa16 (TT16), a transcript regulator belonging to the B(sister) MADS box proteins, regulates proper endothelial differentiation and proanthocyanidin accumulation in the seed coat. Our understanding of its other physiological roles, however, is limited. In this study, the physiological and developmental roles of TT16 in an important oil crop, canola (Brassica napus), were dissected by a loss-of-function approach. RNA interference (RNAi)-mediated down-regulation of tt16 in canola caused dwarf phenotypes with a decrease in the number of inflorescences, flowers, siliques, and seeds. Fluorescence microscopy revealed that tt16 deficiency affects pollen tube guidance, resulting in reduced fertility and negatively impacting embryo and seed development. Moreover, Bntt16 RNAi plants had reduced oil content and altered fatty acid composition. Transmission electron microscopy showed that the seeds of the RNAi plants had fewer oil bodies than the nontransgenic plants. In addition, tt16 RNAi transgenic lines were more sensitive to auxin. Further analysis by microarray showed that tt16 down-regulation alters the expression of genes involved in gynoecium and embryo development, lipid metabolism, auxin transport, and signal transduction. The broad regulatory function of TT16 at the transcriptional level may explain the altered phenotypes observed in the transgenic lines. Overall, the results uncovered important biological roles of TT16 in plant development, especially in fatty acid synthesis and embryo development.
透明种皮 16 蛋白（TT16）是一种属于 B（姐妹）MADS 盒蛋白的转录调控因子，它调节内皮细胞的正常分化和种皮中原花青素的积累。然而，我们对其其他生理作用的了解是有限的。在这项研究中，通过功能丧失的方法，解析了 TT16 在一种重要的油料作物油菜（Brassica napus）中的生理和发育作用。油菜中的 tt16 通过 RNA 干扰（RNAi）下调导致矮化表型，花序、花朵、角果和种子数量减少。荧光显微镜显示 tt16 缺陷影响花粉管导向，导致育性降低，并对胚胎和种子发育产生负面影响。此外，Bntt16 RNAi 植株的含油量降低，脂肪酸组成发生改变。透射电子显微镜显示，RNAi 植株的种子比非转基因植株的油体少。此外，tt16 RNAi 转基因系对生长素更敏感。进一步的微阵列分析表明，tt16 下调改变了与雌蕊和胚胎发育、脂质代谢、生长素运输和信号转导相关的基因的表达。TT16 在转录水平上的广泛调节功能可能解释了转基因系中观察到的表型改变。总的来说，这些结果揭示了 TT16 在植物发育中的重要生物学作用，特别是在脂肪酸合成和胚胎发育中。
