Batista P P, Santos J F, Oliveira N T, Pires A P D, Motta C M S, Luna-Alves Lima E A
Departamento de Genética, Universidade Federal de Pernambuco, Recife, PE, Brasil.
Genet Mol Res. 2008 Aug 5;7(3):706-17. doi: 10.4238/vol7-3gmr422.
The Aspergillus genus belongs to a filamentous fungal group characterized by wide dispersion in the environment. Some species are associated with diseases, especially in immunocompromised patients, while others are of economical importance due to aflatoxin production or biotechnological applications. Its species identification is nowadays performed by traditional techniques combined with molecular markers, resulting in a higher efficiency of isolate characterization. In the present study, internal transcribed spacer, inter-simple sequence repeats (ISSR), and random amplified polymorphic DNA (RAPD) molecular markers were used, with the aim of genetically characterizing strains of Aspergillus flavus and strains of other species of the A. flavus group. High genetic diversity was revealed by RAPD and by ISSR, in which the use of the (GACA)4 primer yielded a higher diversity than with the (GTG)5 primer, although the latter showed a characteristic banding profile for each species. These data were used to create a similarity matrix for the construction of dendrograms by means of the UPGMA method. The ISSR and RAPD profiles showed that among the strains previously identificated as A. flavus, one should be A. oryzae, one A. parasiticus and two A. tamarii. On the other hand, a strain previously identified as A. parasiticus should be A. flavus. All these strains were retested by traditional methods and their new species identification was confirmed. These results strongly support the need for using molecular markers as an auxiliary tool in differentiating fungal species and strains.
曲霉属属于丝状真菌类群，其特点是在环境中广泛分布。一些物种与疾病有关，特别是在免疫功能低下的患者中，而其他一些物种由于产生黄曲霉毒素或具有生物技术应用价值而具有经济重要性。如今，其物种鉴定是通过传统技术与分子标记相结合来进行的，从而提高了分离株特征描述的效率。在本研究中，使用了内部转录间隔区、简单序列重复区间（ISSR）和随机扩增多态性DNA（RAPD）分子标记，目的是对黄曲霉菌株和黄曲霉群其他物种的菌株进行遗传特征分析。RAPD和ISSR揭示了较高的遗传多样性，其中使用（GACA）4引物产生的多样性高于（GTG）5引物，尽管后者对每个物种都显示出特征性的条带图谱。这些数据用于创建相似性矩阵，通过非加权组平均法（UPGMA）构建树状图。ISSR和RAPD图谱显示，在先前鉴定为黄曲霉的菌株中，一株应为米曲霉，一株为寄生曲霉，两株为溜曲霉。另一方面，一株先前鉴定为寄生曲霉的菌株应为黄曲霉。所有这些菌株都通过传统方法重新进行了检测，其新的物种鉴定得到了证实。这些结果有力地支持了使用分子标记作为区分真菌物种和菌株的辅助工具的必要性。
