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

[0416314] Alternaria真菌属的每一种在植物病害、食品毒理学、医学真菌学和生态学方面都具有重要的经济意义，但这一大型属尚未利用现代DNA分析工具进行全面研究。迫切需要一个可行的分类系统，以确保物种的一致和可靠的鉴定，并促进比较生物学的先进研究。为此，亚利桑那大学的Barry Pryor和华盛顿州立大学的Tobin Peever合作研究的主要目标是：1)基于多个基因DNA序列的比较，建立种间进化关系；2)基于种内居群间DNA的比较，重新审视并建立新的种间划分标准；3)评价通过DNA分析验证的物种形态特征。在这些目标中还嵌入了其他目标，即创建基于形态学特征的分类识别密钥，供研究、工业和监管专业人员使用，并开发一个在线数据库，用于传播这些研究和其他相关研究产生的数据。该数据库将作为一个世界范围内的资源，以促进当代对互孢菌和相关真菌的研究。在无性繁殖真菌的进化方面，提出的研究范围既及时又全面，其中交交菌是一个重要的代表。一般来说，大多数生物的分类学主要是基于性结构的发育和特征，这通常已被证明与基于DNA分析的进化关系是一致的。因此，研究无性真菌的主要限制之一是缺乏性结构；直到最近才开始研究无性真菌的特征，并将其与DNA分析得出的数据进行对比。然而，这些研究很少涉及种群间的种内变异，而种内变异是确定物种边界的关键。在互花属中，无性性状存在着相当大范围的种间和种内多样性。此外，许多互花孢属物种在大地理区域的出现为全面研究种内变异提供了理想的机会。因此，互交菌中形态特征的多样性为检验与无性性状进化意义相关的假设，以及比较无性真菌基于形态的分类和基于dna的分类提供了肥沃的土壤。将无性真菌与有性真菌有效整合到一个共同的进化框架中是世界范围内真菌学研究的一个广泛认可的目标。对交替菌的全面研究将对这一目标作出重大贡献。更重要的是，该研究为未来研究无性真菌谱系和无性生物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.