Collaborative Proposal: Integrating Morphological and Molecular Systematics of Alternaria and Related Fungal Genera

链格孢菌属的任何一种真菌在植物病害、食品毒理学、医学真菌学和生态学中都具有重要的经济价值，但这一大属还没有被用现代DNA分析工具进行全面的研究。迫切需要一个可行的分类学系统，以确保一致和可靠的物种识别，并促进比较生物学的高级研究。为此，亚利桑那大学的Barry Pryor和华盛顿州立大学的Tobin Peever的合作工作的主要目标是：1)基于几个基因的DNA序列的比较，建立交链孢属物种之间的进化关系；2)基于物种内种群之间的DNA比较，重新检查和建立划分交链孢属物种的新标准；以及3)评估通过DNA分析验证的关键定义物种的形态特征。在这些目标中嵌入了其他目标，即根据形态特征创建分类识别关键字，可供研究、行业和监管专业人员使用，并开发一个在线数据库，用于传播由这些研究和其他相关研究产生的数据。该数据库将成为促进链格孢菌和相关真菌当代研究的全球资源。关于无性繁殖真菌的进化，拟议的研究范围既及时又全面，交链孢属是其中的关键代表。一般来说，大多数生物的分类主要是基于性结构的发展和特征，这通常被证明与基于DNA分析的进化关系是一致的。因此，无性真菌研究的主要局限之一是缺乏性结构；直到最近，才开始用来自DNA分析的数据来检查和对比无性真菌的特征。然而，这些研究很少涉及种群间的种内变异，这对划定物种之间的边界至关重要。在交链孢属中，无性性状存在相当大范围的种间和种内多样性。此外，交链孢属的许多种在大范围的地理区域内出现，为全面研究种内变异提供了理想的机会。因此，链格孢属中包含的形态特征的多样性为检验与无性特征的进化意义有关的假说以及比较基于形态的分类和基于DNA的无性真菌分类提供了肥沃的土壤。将无性真菌与有性真菌有效地整合到一个共同的进化框架中，是世界各国公认的真菌研究目标。对链格孢菌的全面研究将对这一目标作出重大贡献。更重要的是，交链孢属无性谱系中物种的多样性和进化为未来研究形成无性真菌谱系和无性生物体的进化过程奠定了基础。

0416314Peever Species of the fungus genus Alternaria are economically important in plant disease, food toxicology, medical mycology, and ecology, yet this large genus has not been comprehensively studied using modern tools of DNA analysis. A workable taxonomic system is critically needed that will ensure consistent and reliable identification of species and promote advanced studies in comparative biology. Toward this end, the principal objectives of collaborative work by Barry Pryor at University of Arizona and Tobin Peever at Washington State University are to: 1) establish evolutionary relationships among Alternaria species based upon comparison of DNA sequences from several genes, 2) re-examine and establish new criteria for delimiting Alternaria species based upon comparison of DNA among populations within species, and 3) evaluate morphological characters that critically define species validated by DNA analysis. Embedded within these objectives are additional goals of creating taxonomic identification keys based upon morphological characters that can be used by research, industry, and regulatory professionals, and developing an on-line database for the dissemination of data generated from these and other related studies. This database will serve as a world-wide resource for the advancement of contemporary research on Alternaria and related fungi. The scope of the proposed research is both timely and comprehensive in regard to the evolution of asexually-reproducing fungi, of which Alternaria is a key representative. In general, taxonomy for most organisms is based primarily on the development and characteristics of sexual structures, which normally have proven to be consistent with evolutionary relationships based upon DNA analyses. Thus, one of the primary limitations in the study of asexual fungi is the lack of sexual structures; only recently have studies begun to examine and contrast the characteristics of asexual fungi with data derived from DNA analysis. However, these studies seldom address intra-specific variation among populations, which is critical for delimiting the boundaries between species. Within Alternaria, a considerable range of inter- and intra specific diversity exists in asexual characters. Moreover, the occurrence of many Alternaria species over large geographic areas provides an ideal opportunity for comprehensive studies on intra-specific variation. Thus, the diversity in morphological traits encompassed within Alternaria provides a fertile ground for testing hypotheses relating to the evolutionary significance of asexual characters, and for comparing morphology-based taxonomy with DNA-based taxonomy of asexual fungi. The effective integration of the asexual fungi into a common evolutionary framework with the sexual fungi is a widely recognized goal of mycological research worldwide. A comprehensive study of Alternaria will contribute significantly to this objective. More importantly, the diversity and evolution of species within the asexual lineage of Alternaria positions this study as a foundation for future research into evolutionary processes that shape asexual fungal lineages and asexual organisms in general.