Analysis of Evolutionary History of Phytopathogenic Fungi based upon Evidence from DNA Genealogies

2002年12月和2004年3月，在智利共和国第一区（Tarapaka）分别在0- 1000 m和2000- 3500 m海拔高度收集野生番茄（Lycopersicon peruvianum和L.chilense）。从野生番茄的新鲜叶、茎和根中共获得约650个真菌分离物，其中250个已通过形态学和分子标准鉴定。在分离到的菌株中，我们可以找到约20个尖孢镰刀菌。这些尖孢镰刀菌分离物对任何番茄测试品种均未显示致病性，表明它们是非致病性的。有趣的是，基于Rhibosomal DNA基因间间隔区（rDNA-IGS）序列的系统发育分析显示，来自野生番茄的非致病性尖孢镰刀菌分离物与尖孢镰刀菌F.oxysporum f.栽培番茄枯萎病的病原菌--番茄枯萎病菌（Lycopersici）。这表明：（1）野生番茄上的非致病性尖孢镰刀菌是番茄枯萎病菌的古近系;（2）致病性尖孢镰刀菌是由非致病性尖孢镰刀菌进化而来的;（3）番茄枯萎病菌与番茄共进化。这项研究是在Peever博士，T。L.华盛顿州立大学的博士和奇石勒，C。美国农业部农业研究所明尼苏达大学

In December 2002 and March 2004, a tield-stage collection of wild tomatoes (Lycopersicon peruvianum and L.chilense) was made in 0-1000m and 2000-3500m of altitude, respectively, in Region I(Tarapaka) of Republic of Chile. A total of ca, 650 fungal isolates were obtained from fresh leaves, stems, and roots of wild tomatoes and 250 of them have been identified by morphological and molecular criteria. We could find about 20 Fusarium oxysporum among the isolates. These F.oxysporum isolates did not show pathogenicity to any tomato tester-varieties, suggesting that they are non-pathogenic. Interestingly, phylogenetic analysis based on the rhibosomal DNA inter genic spacer (rDNA-IGS) sequences revealed that the non-pathogenic F.oxysporum isolats from wild tomatos are closely related to F.oxysporum f. sp. lycopersici, the pathogen of wilt disease of cultivated tomato (L.esculentum), in F.oxysporum tree. This suggested that (1)the non-pathogenic F.oxysporum on wild tomato is an ancient-relatives of the tomato wilt fungus, (2)the pathogenic F.oxysporum had been deliverd from the non-pathogenic F.oxysporum, (3)tomato wilt pathogen has been coevolved with tomatoes. This study was done under cooperation with Dr.Peever, T. L. of Washington State University and Dr.Kistler, C. of USDA-ARS, Minnesota University.