Haudenshield James S, Hartman Glen L
United States Department of Agriculture, Agricultural Research Service, and Department of Crop Sciences, University of Illinois, Urbana 61801.
Plant Dis. 2015 May;99(5):575-579. doi: 10.1094/PDIS-07-14-0772-SR.
Herbarium specimens are useful to compare attributes of the past to attributes of today and predictions into the future. In this study, herbarium specimens from 1887 to 2006 were used to identify Phakopsora pachyrhizi and P. meibomiae, the two known fungal species that cause soybean rust. Historically, these two species differed in geographic distribution, with P. pachyrhizi confined to Asia and Australia, and P. meibomiae confined to the Americas. In our analyses, herbarium specimens were used to determine whether it was possible to extract adequate useful DNA from the fungal structures. If present, quantitative PCR primers specific to P. pachyrhizi, P. meibomiae, or to a third group inclusive of many rust species could be used to speciate the fungus. Of the 38 archival specimens, 11 were positive for P. pachyrhizi, including a 1912 specimen from Japan; 15 were positive for P. meibomiae, including a 1928 specimen from Brazil and two 1923 specimens from the Philippines; and 12 (including all African accessions) were negative for both species. Five specimens were positive in the more inclusive rust assay; all had been labeled as P. pachyrhizi and none were on soybean. These results demonstrate the feasibility of DNA genotyping in archaeophytopathological investigations.
植物标本有助于将过去的特征与现在的特征进行比较，并对未来进行预测。在本研究中，使用了1887年至2006年的植物标本，以鉴定引起大豆锈病的两种已知真菌物种——大豆锈病菌（Phakopsora pachyrhizi）和美澳型双胞锈菌（P. meibomiae）。从历史上看，这两个物种在地理分布上有所不同，大豆锈病菌局限于亚洲和澳大利亚，美澳型双胞锈菌局限于美洲。在我们的分析中，植物标本被用于确定是否有可能从真菌结构中提取足够有用的DNA。如果存在，可以使用针对大豆锈病菌、美澳型双胞锈菌或包括许多锈菌物种的第三组的定量PCR引物来鉴定该真菌。在38份存档标本中，11份对大豆锈病菌呈阳性，包括一份1912年来自日本的标本；15份对美澳型双胞锈菌呈阳性，包括一份1928年来自巴西的标本和两份1923年来自菲律宾的标本；12份（包括所有非洲标本）对这两个物种均呈阴性。5份标本在更具包容性的锈菌检测中呈阳性；所有标本都被标记为大豆锈病菌，且均非来自大豆。这些结果证明了在古植物病理学研究中进行DNA基因分型的可行性。
