Production of a host-specific toxin by germinating spores ofAlternaria brassicicola☆
Production of a host-specific toxin by germinating spores ofAlternaria brassicicola☆
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甘蓝链格孢菌孢子萌发产生宿主特异性毒素☆
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
K. Kohmoto
中科院分区：
文献类型：
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作者：
H. Otani;A. Kohnobe;M. Kodama;K. Kohmoto
摘要芸苔链格孢菌孢子悬浮液对芸苔属植物具有致病性。被孵育在屋檐表面。收集孢子萌发液并检查生物活性。在离体叶片试验中，液体诱导水浸症状，然后在对病原体敏感的叶片上出现棕色坏死病变，但在非寄主叶片上没有引起明显症状。将非致病性的烟草赤星病菌（Alternaria alternata）的孢子与液体结合后接种于叶片上，孢子能像病原菌一样侵入叶片。这些结果表明，A.芸苔属产生一种寄主特异性毒素，并在孢子在叶子上萌发期间释放毒素。通过具有5 kDa截留的超滤膜保留流体的毒素活性。毒素经离子交换层析和凝胶过滤HPLC纯化。SDS-聚丙烯酰胺凝胶电泳测得该毒素的分子量为35 kDa。该毒素对热不稳定，用蛋白酶K处理后也失去活性。因此，命名为AB-毒素的毒素可能是一种蛋白质，是链格孢属产生的许多宿主特异性毒素中最早描述的。
Abstract Spore suspensions ofAlternaria brassicicolapathogenic toBrassicaspp. were incubated on the surface ofBrassicaleaves. The spore germination fluid was collected and examined for biological activity. In a detached leaf assay, the fluid induced water-soaking symptoms followed by brown necrotic lesions onBrassicaleaves susceptible to the pathogen but did not cause visible symptoms on non-host leaves. When spores of the non-pathogenic speciesAlternaria alternatawere combined with the fluid and inoculated on the leaves, the spores could invadeBrassicaleaves, just as the pathogen did. These results indicate thatA. brassicicolaproduces a host-specific toxin(s) and releases it during spore germination on the leaves. Toxin activity of the fluid was retained by an ultrafiltration membrane with a 5 kDa cut off. The toxin was purified by ion exchange chromatography and gel filtration HPLC. The molecular weight of the toxin was estimated to be 35 kDa by SDS-polyacrylamide gel electrophoresis. The activity of the toxin was heat labile and was also lost after treatment with proteinase K. Thus, the toxin named AB-toxin is probably a protein, the first described among the many host-specific toxins produced byAlternariaspecies.