Eto Y, Ikeda K, Chuma I, Kataoka T, Kuroda S, Kikuchi N, Don L D, Kusaba M, Nakayashiki H, Tosa Y, Mayama S
Faculty of Agriculture, Kobe University, Japan.
Mol Gen Genet. 2001 Jan;264(5):565-77. doi: 10.1007/s004380000343.
We examined the distribution and activity of six transposable elements found in the blast fungus, Pyricularia spp. Sixty-eight isolates from various gramineous plants were used for the survey, and the elements were plotted on a dendrogram constructed on the basis of their rDNA-ITS2 sequences. MGR586 and Pot2 (Class II elements), Mg-SINE (SINE-like element) and MGR583 (LINE-like retrotransposon) were widely distributed among the Pyricularia isolates, suggesting that they are old elements which arose in, or invaded, the Pyricularia population at very early stages in its evolution. By contrast, the distribution of the LTR-retrotransposons MAGGY and Grasshopper was limited or sporadic, suggesting that they are relatively new elements which recently invaded the Pyricularia population by means of horizontal transfer events. The activity of these elements was evaluated by Southern analysis in progenies derived from a cross between a Setaria isolate and a Triticum isolate. Many new MAGGY signals were observed, which were absent in the parental isolates, at various stages of the sexual cycle and following vegetative growth. In contrast, the other elements yielded few, if any, such signals. Analysis of the sequences flanking the new MAGGY insertions revealed that they were each associated with a 5-bp target-site duplication at both ends of the insertion. These data suggested that MAGGY was the most active of the elements tested for transposition in Pyricularia.
我们研究了稻瘟病菌（Pyricularia spp.）中发现的六种转座元件的分布和活性。从各种禾本科植物中分离出68个菌株用于此项研究，并根据其rDNA-ITS2序列构建的系统发育树绘制这些元件。MGR586和Pot2（II类元件）、Mg-SINE（类SINE元件）和MGR583（类LINE反转录转座子）在稻瘟病菌分离株中广泛分布，这表明它们是在稻瘟病菌进化的早期阶段出现或侵入该菌群体的古老元件。相比之下，LTR反转录转座子MAGGY和Grasshopper的分布有限或呈零星分布，这表明它们是相对较新的元件，最近通过水平转移事件侵入了稻瘟病菌群体。通过Southern分析评估了这些元件在狗尾草分离株和小麦分离株杂交后代中的活性。在有性生殖周期的各个阶段以及营养生长后，观察到许多新的MAGGY信号，这些信号在亲本分离株中不存在。相比之下，其他元件几乎没有产生这样的信号（如果有的话）。对新的MAGGY插入侧翼序列的分析表明，它们在插入两端均与一个5bp的靶位点重复相关。这些数据表明，MAGGY是在稻瘟病菌中转座测试的元件中活性最高的。
