Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang 310058, China.
Environ Microbiol Rep. 2013 Feb;5(1):135-42. doi: 10.1111/1758-2229.12012. Epub 2012 Nov 27.
Previously, we found a 199 bp element which inserted into the promoter of PdCYP51B gene in Penicillium digitatum, was associated with the overexpression of this gene and DMI fungicides resistance. However, the mechanism how this 199 bp element upregulate the expression of downstream gene was completely unknown. In the current study, we confirmed that this 199 bp element was a MITE-like element, designated as PdMLE1. blast searching and Southern blot showed that this 199 bp element was unique to P. digitatum. Genome-wide localization of PdMLE1 showed that it preferentially inserted into A + T rich regions, and several copies localized at the coding or regulation regions of genes were found. Penicillium digitatum mutant harbouring the PdMLE1 fused GFP gene showed the strong green fluorescence, indicating the powerful promoter activity of PdMLE1. By promoter deletion method, we identified a 20 bp core sequence in PdMLE1 which was associated with its promoter activity. In addition, we also limited the core element of PdCYP51B promoter to a 368 bp region. Collectively, we proposed a model that PdMLE1 acted as a powerful promoter and most likely recruited the transcription factor(s), therefore led to the overexpression of PdCYP51B gene and conferred P. digitatum with DMI resistance. This is the first regulation model of transposon resulted fungicide resistance proved in plant pathogens.
先前，我们发现一个 199bp 的元件插入到青霉菌 PdCYP51B 基因的启动子中，与该基因的过表达和 DMI 杀菌剂抗性有关。然而，这个 199bp 元件如何上调下游基因的表达机制尚完全不清楚。在本研究中，我们证实这个 199bp 元件是一个 MITE 样元件，命名为 PdMLE1。blast 搜索和 Southern blot 显示，这个 199bp 元件是青霉菌的特有元件。PdMLE1 的全基因组定位显示，它优先插入 A+T 丰富的区域，并且在基因的编码或调控区域发现了几个拷贝。携带 PdMLE1 融合 GFP 基因的青霉菌突变体表现出强烈的绿色荧光，表明 PdMLE1 具有强大的启动子活性。通过启动子缺失方法，我们确定了 PdMLE1 中与启动子活性相关的 20bp 核心序列。此外，我们还将 PdCYP51B 启动子的核心元件限制在 368bp 区域。总之，我们提出了一个模型，即 PdMLE1 作为一个强大的启动子，很可能招募转录因子，从而导致 PdCYP51B 基因的过表达，并赋予青霉菌对 DMI 的抗性。这是植物病原菌中转座子导致杀菌剂抗性的第一个调控模型。
