Babula-Skowrońska Danuta, Ludwików Agnieszka, Cieśla Agata, Olejnik Anna, Cegielska-Taras Teresa, Bartkowiak-Broda Iwona, Sadowski Jan
Institute of Plant Genetics, Polish Academy of Sciences, Strzeszyńska 34, 60-479, Poznan, Poland,
Plant Mol Biol. 2015 Jul;88(4-5):445-57. doi: 10.1007/s11103-015-0334-x. Epub 2015 Jun 10.
In this report we characterized the Arabidopsis ABI1 gene orthologue and Brassica napus gene paralogues encoding protein phosphatase 2C (PP2C, group A), which is known to be a negative regulator of the ABA signaling pathway. Six homologous B. napus sequences were identified and characterized as putative PP2C group A members. To gain insight into the conservation of ABI1 function in Brassicaceae, and understand better its regulatory effects in the drought stress response, we generated transgenic B. napus plants overexpressing A. thaliana ABI1. Transgenic plants subjected to drought showed a decrease in relative water content, photosynthetic pigments content and expression level of RAB18- and RD19A-drought-responsive marker genes relative to WT plants. We present the characterization of the drought response of B. napus with the participation of ABI1-like paralogues. The expression pattern of two evolutionarily distant paralogues, BnaA01.ABI1.a and BnaC07.ABI1.b in B. napus and their promoter activity in A. thaliana showed differences in the induction of the paralogues under dehydration stress. Comparative sequence analysis of both BnaABI1 promoters showed variation in positions of cis-acting elements that are especially important for ABA- and stress-inducible expression. Together, these data reveal that subfunctionalization following gene duplication may be important in the maintenance and functional divergence of the BnaABI1 paralogues. Our results provide a framework for a better understanding of (1) the role of ABI1 as a hub protein regulator of the drought response, and (2) the differential involvement of the duplicated BnaABI1 genes in the response of B. napus to dehydration-related stresses.
在本报告中，我们对拟南芥ABI1基因的直系同源物以及油菜中编码蛋白磷酸酶2C（PP2C，A组）的旁系同源基因进行了表征，已知该蛋白是脱落酸（ABA）信号通路的负调控因子。我们鉴定出了六个同源的油菜序列，并将其表征为假定的A组PP2C成员。为了深入了解ABI1功能在十字花科中的保守性，并更好地理解其在干旱胁迫响应中的调控作用，我们构建了过表达拟南芥ABI1的转基因油菜植株。与野生型植株相比，遭受干旱处理的转基因植株的相对含水量、光合色素含量以及RAB18和RD19A干旱响应标记基因的表达水平均有所降低。我们展示了油菜在类似ABI1旁系同源物参与下的干旱响应特征。油菜中两个进化距离较远的旁系同源物BnaA01.ABI1.a和BnaC07.ABI1.b的表达模式及其在拟南芥中的启动子活性表明，在脱水胁迫下这两个旁系同源物的诱导存在差异。对两个BnaABI1启动子的比较序列分析表明，顺式作用元件的位置存在变异，这些元件对于ABA和胁迫诱导表达尤为重要。总之，这些数据表明基因复制后的亚功能化可能在BnaABI1旁系同源物的维持和功能分化中发挥重要作用。我们的研究结果为更好地理解以下两点提供了一个框架：（1）ABI1作为干旱响应中枢蛋白调节因子的作用；（2）复制的BnaABI1基因在油菜对脱水相关胁迫响应中的不同参与情况。
