School of Agricultural Sciences, Nagoya University, Chikusa, Nagoya 464-01, Japan.
Appl Environ Microbiol. 1994 Sep;60(9):3055-62. doi: 10.1128/aem.60.9.3055-3062.1994.
A total of 99 strains of 11 Alternaria species, including 68 strains of seven fungi known to produce host-specific toxins, were subjected to analysis of restriction fragment length polymorphism (RFLP) in nuclear ribosomal DNA (rDNA). Total DNA was digested with XbaI, and the Southern blots were probed with a nuclear rDNA clone of Alternaria kikuchiana. The hybridization gave 17 different RFLPs from the 99 strains. On the basis of these RFLPs, populations of host-specific toxin-producing fungi could not be differentiated from one another nor from nonpathogenic A. alternata. Each population of the toxin-producing fungi carried rDNA variants. Nine different types, named A1 to A6 and B1 to B3, were detected among the toxin-producing fungi and nonpathogenic A. alternata. All of the populations contained the type A4 variant, and the other rDNA types were also shared by different toxin-producing fungi and A. alternata. In contrast, Alternaria species that are morphologically distinguishable from A. alternata could be differentiated from A. alternata on the basis of the rDNA RFLPs. Polymorphisms in rDNA digested with HaeIII and MspI were also evaluated in 61 Alternaria strains. These restriction enzymes produced 31 variations among all of the samples. The seven toxin-producing fungi and nonpathogenic A. alternata could not be resolved by phylogenetic analysis based on the RFLPs, although they could be differentiated from the other Alternaria species studied. These results provide support for the hypothesis that Alternaria fungi known to produce host-specific toxins are intraspecific variants of A. alternata specialized in pathogenicity.
总共分析了 11 种链格孢属的 99 个菌株，其中包括已知产生宿主特异性毒素的 7 种真菌中的 68 个菌株，这些真菌的核核糖体 DNA（rDNA）进行了限制片段长度多态性（RFLP）分析。用 XbaI 消化总 DNA，并用Alternaria kikuchiana 的核 rDNA 克隆进行 Southern 印迹杂交。杂交得到了 99 个菌株中的 17 种不同的 RFLP。基于这些 RFLP，宿主特异性毒素产生真菌的种群彼此之间以及与非致病性的 A. alternata 无法区分。产生毒素的真菌种群各携带 rDNA 变体。在产毒真菌和非致病性 A. alternata 中检测到 9 种不同的类型，分别命名为 A1 到 A6 和 B1 到 B3。所有种群都含有 A4 变体，其他 rDNA 类型也存在于不同的产毒真菌和 A. alternata 中。相比之下，形态上与 A. alternata 不同的链格孢属物种可以基于 rDNA RFLP 与 A. alternata 区分开来。还评估了用 HaeIII 和 MspI 消化 rDNA 的多态性，在 61 个 Alternaria 菌株中。这两种限制酶在所有样本中产生了 31 种变化。这七种产毒真菌和非致病性 A. alternata 无法通过基于 RFLP 的系统发育分析来区分，尽管它们可以与研究中的其他 Alternaria 物种区分开来。这些结果支持了这样一种假设，即已知产生宿主特异性毒素的链格孢真菌是专门在致病性方面具有特异性的 A. alternata 的种内变体。
