Judelson H S, Dudler R, Pieterse C M, Unkles S E, Michelmore R W
Center for Engineering Plants for Resistance Against Pathogens, University of California, Davis 95616.
Gene. 1993 Oct 29;133(1):63-9. doi: 10.1016/0378-1119(93)90225-r.
Procedures were identified for manipulating the expression of genes in the oomycete fungus, Phytophthora infestans. The activities of five putative promoter sequences, derived from the 5' regions of oomycete genes, were measured in transient assays performed in protoplasts and in stable transformants. The sequences tested were from the ham34 and hsp70 genes of Bremia lactucae, the actin-encoding genes of P. infestans and P. megasperma, and a polyubiquitin-encoding gene of P. infestans. Experiments using the GUS reporter gene (encoding beta-glucuronidase) demonstrated that each 5' fragment had promoter activity, but that their activities varied over a greater than tenfold range. Major variation was revealed in the level of transgene expression in individual transformants containing the same promoter::GUS or promoter::lacZ fusion. The level of expression was not simply related to the number of genes present, suggesting that position effects were also influencing expression. Fusions between the ham34 promoter, and full-length and partial GUS genes in the antisense orientation blocked the expression of GUS in protoplasts and in stable transformants.
已确定了用于调控卵菌纲真菌致病疫霉（Phytophthora infestans）中基因表达的方法。从卵菌纲基因的5'区域衍生而来的五个假定启动子序列的活性，在原生质体和稳定转化体中进行的瞬时分析中进行了测定。所测试的序列来自莴苣盘梗霉（Bremia lactucae）的ham34和hsp70基因、致病疫霉和大孢疫霉（P. megasperma）的肌动蛋白编码基因，以及致病疫霉的一个多聚泛素编码基因。使用GUS报告基因（编码β-葡萄糖醛酸酶）的实验表明，每个5'片段都具有启动子活性，但其活性在超过十倍的范围内变化。在含有相同启动子::GUS或启动子::lacZ融合体的单个转化体中，转基因表达水平显示出主要差异。表达水平与存在的基因数量并非简单相关，这表明位置效应也在影响表达。ham34启动子与全长和部分GUS基因以反义方向融合，可阻断原生质体和稳定转化体中GUS的表达。
