The Methodological Study On Taxonomy Of The Genus Alternaria Nees

Alternaria is a dematiaceous mitosporic fungus with a wide variety of habitats and geographical distribution. More than 95% species are very important plant pathogens, some species can cause human and animal diseases, and some are potent biological resources. So there are theoretic and practical significances for Alternaria correct classification and identification.However, conidial morphology is highly variable due to the environment and culture condition. The morphology-based taxonomic method has not been met the demands, so we need seeking other taxonomic methods to compensate the deficiency. To date, many mycologists study the taxonomic criteria at Alternaria species level by many means, but there are some confusion and divergent views. All of these affect Alternaria development, communication and application. The aim of this study is to seek reliable and valuable taxonomy methods by morphological, biochemical, molecular biological and phytopathological means to resolve the problems.We had collected more than 2000 specimens from more than 20 provinces. From these collections and another 3000 herbarium specimens identified, we gain about 250 isolates. Based on the conidial and sporulation pattern characters, we described and illustrated 44 Alternaria taxa. Among them, there are 7 new species, 1 new combination, 5 Chinese newly recorded species (see addendum), 2 uncertain species, and 29 reported species from China. Proteins are the direct products of gene. In order to test the interspecies difference from protein level, we chose 15 Alternaria isolates with polyacrglamide gel electrothoresis of soluble protein analysis, and 21 isolates with esterase isozyme analysis. Results show that the protein pattern is polymorphic of interspecies. The EST isozyme pattern is polymorphic of interspecies, while it is relatively homogeneous of intraspecies. Cluster analyses with UPGMA are corresponded with morphological identification.