REAL, an LTR retrotransposon from the plant pathogenic fungus Alternaria alternata
REAL, an LTR retrotransposon from the plant pathogenic fungus Alternaria alternata
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DOI：
10.1007/s004380051210
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发表时间：
2000-05-01
期刊：
影响因子：
--
通讯作者：
Tsuge, T
中科院分区：
文献类型：
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作者：
Kaneko, I;Tanaka, A;Tsuge, T
从日本梨树交替病菌15A株中分离到一个反转录转座子，该菌株通过产生一种被称为ak -毒素的寄主特异性毒素，在某些品种的日本梨树中引起黑斑病。我们将该元件命名为REAL (Alternaria alternata Retrotransposon)，全长6046 bp，包含218 bp的直接长末端重复序列（lts）。发现目标位点重复5bp。REAL包含两个长而重叠的orf。第一个ORF与逆转录病毒gag基因具有同源性。第二个ORF依次与蛋白酶、逆转录酶、RNase H和整合酶结构域具有同源性。逆转录酶结构域的系统发育比较表明，REAL位于LTR逆转录转座子的Ty3/gypsy组，与来自Magnaporthe grisea的蚱蜢关系最密切。Northern分析检测到大约2.0和6.0 kb的REAL转录本。6.0 kb的物种对应于该元件的全长转录本。通过Southern分析，在日本梨病型的13个品系中有12个品系中发现了该元素，这些品系的条带模式、拷贝数和信号强度是不同的。在一些（但不是全部）其他测试菌株中也发现了real -相关的元素，包括非致病性交替芽孢杆菌和其他致病菌株，它们通过产生不同的宿主特异性毒素在不同的植物物种上引起疾病。这些结果表明，REAL在金针桃中的分布不具有病型特异性。
A retrotransposon was isolated and characterized from strain 15A of the Japanese pear pathotype of Alternaria alternata, which causes black spot disease in certain cultivars of Japanese pear by producing a host-specific toxin known as AK-toxin. The element, which we have named REAL (Retrotransposon of Alternaria alternata), is 6046 bp in size and contains direct long terminal repeats (LTRs) of 218 bp. Target-site duplication of 5 bp was found. REAL contains two long overlapping ORFs. The first ORF shows homology to retroviral gag genes. The second ORF has homology to protease, reverse transcriptase, RNase H and integrase domains of the retroelement pol genes, in that order. Phylogenetic comparison of reverse transcriptase domains from retrotransposons placed REAL in the Ty3/gypsy group of LTR retrotransposons, most closely related to grasshopper from Magnaporthe grisea. Northern analysis detected REAL transcripts of about 2.0 and 6.0 kb. The 6.0-kb species corresponds to a full-length transcript of the element. The element was found by Southern analysis in 12 out of 13 strains of the Japanese pear pathotype, and the banding patterns, copy numbers and signal intensities in these strains were variable. REAL-related elements were also found in some, but not all, of the other strains tested, including nonpathogenic A. alternata and other pathotypes, which cause diseases on different plant species by producing distinct hostspecific toxins. These results suggest that the distribution of REAL in A. alternata is not pathotype specific.