Institute for Plant Breeding, Christian-Albrechts-University of Kiel, Olshausenstr. 40, 24118, Kiel, Germany.
Planta. 2010 Nov;232(6):1309-24. doi: 10.1007/s00425-010-1254-2. Epub 2010 Sep 1.
The protein encoded by the FLOWERING LOCUS T (FT) gene from Arabidopsis thaliana seems to be the long-searched florigen, and over-expression of FT orthologues resulted in accelerated flower development in annual and perennial plants. In the present study, we isolated two allelic mRNA sequences of an FT-homologous gene from apple, which was designated as MdFT1. Using a SSR motif this gene was mapped on LG 12 of apple. Over-expression of MdFT1 in Arabidopsis and the commercially important tree species poplar and apple itself using the CaMV 35S or the Arabidopsis Suc2 promoter resulted in significant accelerated flowering compared with wild-type plants. Transgenic T(0) plants of Arabidopsis flowered 4-6 days on average earlier than wild-type Arabidopsis under LD conditions. Under short-day conditions Suc2::MdFT1 plants of the T(1)-generation flowered after 66 ± 18 days, while wild-type plants flowered about 22 days later. All transgenic Arabidopsis plants showed a normal habit except for the early flowering phenotype. Early flowering was detected 6-10 months after transformation in transgenic polar clones containing MdFT1 driven by the CaMV 35S, whereas plants of the transgenic apple clone T780 set up its first flowers during in vitro cultivation. Based on our results we conclude that MdFT1 is responsible for inducing flowering and that the function of the apple FT1 gene is conserved in annual herbaceous species as well as perennial woody species. Furthermore, we discuss the role of MdFT1 in flower development with regard to the findings of genetic studies on apple.
拟南芥开花时间基因（FLOWERING LOCUS T，FT）编码的蛋白质似乎就是长期寻找的成花素，FT 同源物的过表达导致一年生和多年生植物的开花时间提前。本研究从苹果中分离到一个 FT 同源基因的两个等位基因 mRNA 序列，将其命名为 MdFT1。利用 SSR 标记，该基因被定位在苹果的 LG12 上。利用 CaMV35S 或拟南芥 Suc2 启动子在拟南芥和重要的经济树种杨树及苹果自身中过表达 MdFT1，与野生型相比，开花时间明显提前。在 LD 条件下，转 MdFT1 的拟南芥 T0 代植物比野生型早开花 4-6 天。在短日照条件下，Suc2::MdFT1 的 T1 代植物在 66±18 天后开花，而野生型植物大约晚 22 天开花。除了开花早的表型外，所有的转基因拟南芥植物都表现出正常的习性。含有 CaMV35S 驱动的 MdFT1 的转基因拟南芥极体在转化后 6-10 个月检测到早花，而含有 MdFT1 的转基因苹果克隆 T780 在体外培养期间就开始第一次开花。基于我们的结果，我们得出结论，MdFT1 负责诱导开花，并且苹果 FT1 基因的功能在一年生草本物种和多年生木本物种中是保守的。此外，我们还讨论了 MdFT1 在花发育中的作用，并结合苹果的遗传研究结果进行了讨论。
