Identification and functional characterization of the soybean GmaPPO12 promoter conferring Phytophthora sojae induced expression.

Identification of pathogen-inducible promoters largely lags behind cloning of the genes for disease resistance. Here, we cloned the soybean GmaPPO12 gene and found that it was rapidly and strongly induced by Phytophthora sojae infection. Computational analysis revealed that its promoter contained many known cis-elements, including several defense related transcriptional factor-binding boxes. We showed that the promoter could mediate induction of GUS expression upon infection in both transient expression assays in Nicotiana benthamiana and stable transgenic soybean hairy roots. Importantly, we demonstrated that pathogen-induced expression of the GmaPPO12 promoter was higher than that of the soybean GmaPR1a promoter. A progressive 5’ and 3’ deletion analysis revealed two fragments that were essential for promoter activity. Thus, the cloned promoter could be used in transgenic plants to enhance resistance to phytophthora pathogens, and the identified fragment could serve as a candidate to produce synthetic pathogen-induced promoters.

病原体诱导型启动子的鉴定在很大程度上滞后于抗病基因的克隆。在此，我们克隆了大豆GmaPPO12基因，发现它在受到大豆疫霉菌感染时会迅速且强烈地被诱导。计算分析显示，其启动子包含许多已知的顺式作用元件，包括几个与防御相关的转录因子结合框。我们表明，在本氏烟草的瞬时表达实验以及稳定转基因大豆毛状根中，该启动子在感染时都能够介导GUS表达的诱导。重要的是，我们证明了GmaPPO12启动子的病原体诱导表达高于大豆GmaPR1a启动子。逐步的5’和3’缺失分析揭示了对启动子活性至关重要的两个片段。因此，克隆的启动子可用于转基因植物以增强对疫霉病原体的抗性，并且所鉴定的片段可作为产生合成的病原体诱导型启动子的候选片段。