小麦TaYAB2基因的过量表达造成转基因拟南芥叶片近轴面特征趋向远轴面

Ectopic Expression of TaYAB2, a Member of YABBY Gene Family in Wheat,Causes Partial Abaxialization of Adaxial Epidermises of Leaves in Arabidopsis

叶片极性的建立在叶片形态建成过程中有重要作用。探讨小麦叶片发育的调控机制不仅可以丰富植株形态建成的基础知识,也可以为小麦株型的设计提供理论依据。本研究从小麦中分离出一个YABBY基因家族成员TaYAB2,对其序列特征、表达模式及功能进行了分析。该基因编码的蛋白在N端含有C2C2锌指结构域,C端含有YABBY结构域,与拟南芥中AtYAB2和水稻中OsYAB2同源关系较近。RT-PCR结果显示,该基因在大部分组织器官中广泛表达。进一步的原位杂交分析证实TaYAB2基因的转录产物在小麦苗端、幼叶、侧芽、幼穗等组织器官中高水平积累。在拟南芥中过量表达该基因能够引起转基因拟南芥叶片近轴面特征趋向远轴面。与对照相比,转基因植株中远轴面特征决定基因FIL/YAB1、YAB3、KAN1的表达均呈不同程度的上调,表明TaYAB2基因可能通过调节远轴面特征决定基因FIL/YAB1、YAB3、KAN1等调控叶片近-远轴极性。本研究结果有助于揭示YABBY类基因在小麦侧生器官近-远轴极性建立中的分子机制。

Adaxial-abaxial polarity is an important feature of lateral organs. To study the molecular mechanism of polarity estab- lishment, we isolated a YABBY gene, designated TaYAB2, from the young leaves of wheat. TaYAB2 has a zinc finger-like domain in the N terminus and a YABBY domain in the C terminus. Sequence comparison showed that TaYAB2 is a putative member of the YABBY gene family in wheat. Further expression analysis indicated that TaYAB2 was widely expressed in the lateral organs of wheat. Ectopic expression of TaYAB2 in Arabidopsis caused the partial abaxialization of the adaxial epidermises of leaves with the promotion of the transcript levels of abaxial identity genes, for example, FIL/YAB1, YAB3, and KAN1. These results indicate that TaYAB2 affects the establishment of adaxial-abaxial polarity when ectopically expressed in Arabidopsis.