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I区（塔拉帕卡）海拔0-1000米和2000-3500米的地方分别进行了野生番茄（秘鲁番茄和智利番茄）的田间采集。从野生番茄的鲜叶、茎和根中分离得到约650株真菌，其中250株经形态学和分子鉴定。分离菌株中可检出约20株尖孢镰刀菌。这些尖孢镰刀菌分离株对任何番茄试验品种均未表现出致病性，表明它们是非致病性的。有趣的是，基于基因间间隔（rDNA-IGS）序列的系统发育分析显示，野生番茄非致病性尖孢菌分离株与栽培番茄枯萎病病原菌f.r oxsporum f.sp . lycopersici亲缘关系密切。这表明：(1)野生番茄上的非致病性尖孢镰刀菌是番茄枯萎菌的古亲缘菌；(2)致病性尖孢镰刀菌是由非致病性尖孢镰刀菌传递过来的；(3)番茄枯萎病菌是与番茄共同进化的。这项研究是由华盛顿州立大学的peever博士和明尼苏达大学USDA-ARS的kistler博士合作完成的。

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.