Molecular Systematics of the Non-pedicellate Rust Fungi

所谓锈病是一类重要的专性寄生植物病原真菌。小麦锈病可能是最广为人知的，因为它们严重影响作物产量。虽然寄主植物专一性是锈病的一个标志，但对寄主跟踪和寄主转移的进化模式知之甚少。这种缺乏了解是由于我们对锈菌物种和属之间以及与相关担子菌之间的进化关系或系统发育的基本知识造成的。加州大学伯克利分校的托马斯·布鲁斯博士将使用分子基因组技术在几个分类水平上研究锈菌之间的进化关系。在最广泛的水平上，将分析核糖体基因的DNA核苷酸序列，并将比较主要锈菌群及其可能的真菌近缘之间的突变差异。在较低的分类水平上，将用DNA测序方法研究松树上重要的病原菌Cronartium和Melampsora两属物种之间的进化关系。锈菌之间的关系模式将与松树物种之间的关系模式进行比较，以发现发生寄主植物转移的谱系。这项工作的结果将有助于更好地了解专性植物病原体中的寄主跟踪和寄主转移，并将开发必要的数据库和方法，以促进两个选定属内的物种的快速鉴定。

The so-called rusts are an important group of obligately parasitic plant pathogenic fungi. Wheat rusts are probably the best known because of their serious effects on crop yields. Although host plant specificity is a hallmark of the rusts, little is known about the evolutionary patterns of host tracking and host shifting. This lack of understanding is caused by our rudimentary knowledge of the evolutionary relationships, or phylogeny, of the rusts, both among the rust species and genera and with related basidiomycetes. Dr. Thomas Bruns of the University of California- Berkeley will use molecular genomic techniques to investigate evolutionary relationships at several taxonomic levels among the rust fungi. At the broadest level, DNA nucleotide sequences of the ribosomal genes will be analyzed and mutational differences will be compared among the major groups of rusts and their putative fungal relatives. At lower taxonomic levels, evolutionary relationships among species of two genera, Cronartium and Melampsora, that are important pathogens on pine trees will be investigated by DNA sequencing methods. Patterns of relationship among the rust fungi will be compared with patterns of relationship among pine species to detect lineages where hostplant shifts have occurred. Results from this work should provide a better understanding of host tracking and host shifting in obligate plant pathogens, and will also develop the database and methodology needed to facilitate rapid identification of species within the two selected genera.