Wu Gang, Lin Wan-Ching, Huang Tengbo, Poethig R Scott, Springer Patricia S, Kerstetter Randall A
Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
Proc Natl Acad Sci U S A. 2008 Oct 21;105(42):16392-7. doi: 10.1073/pnas.0803997105. Epub 2008 Oct 10.
Lateral organ polarity in Arabidopsis is regulated by antagonistic interactions between genes that promote either adaxial or abaxial identity, but the molecular basis of this interaction is largely unknown. We show that the adaxial regulator ASYMMETRIC LEAVES2 (AS2) is a direct target of the abaxial regulator KANADI1 (KAN1), and that KAN1 represses the transcription of AS2 in abaxial cells. Mutation of a single nucleotide in a KAN1 binding site in the AS2 promoter causes AS2 to be ectopically expressed in abaxial cells, resulting in a dominant, adaxialized phenotype. We also show that the abaxial expression of KAN1 is mediated directly or indirectly by AS2. These results demonstrate that KAN1 acts as a transcriptional repressor and that mutually repressive interactions between KAN1 and AS2 contribute to the establishment of adaxial-abaxial polarity in plants.
拟南芥的侧生器官极性由促进近轴或远轴特性的基因之间的拮抗相互作用调控，但这种相互作用的分子基础很大程度上尚不清楚。我们发现近轴调节因子不对称叶2（AS2）是远轴调节因子KANADI1（KAN1）的直接靶标，并且KAN1在远轴细胞中抑制AS2的转录。AS2启动子中KAN1结合位点的单个核苷酸突变导致AS2在远轴细胞中异位表达，产生显性的近轴化表型。我们还表明，KAN1的远轴表达直接或间接受AS2介导。这些结果表明，KAN1作为转录抑制因子，并且KAN1与AS2之间的相互抑制相互作用有助于植物近轴-远轴极性的建立。
