Molecular cytogenetic analysis of the chromosome evolution in the mycotoxin-producing Fusarium species

本研究对产真菌毒素镰刀菌的核型和染色体进行了分子细胞遗传学研究。如禾谷镰刀菌，并分析了与该群体进化有关的数据。主要研究结果如下：1.对基因组测序标准菌株PH-1和00-676进行了详细的核型分析，包括染色体数目（n=4）和染色体形态特征。每一条染色体对应一个特定的遗传连锁群.对采自12个国家的21个种（35个菌株）进行了细胞学和电泳核型分析。结果表明，每种植物的染色体数目都是恒定的，且具有种特异性，根据染色体数目可将其分为3个类群，即n=4的类群（9 spp.包括禾谷镰刀菌（F. graminearum）、木贼（Equiseti）和长柄镰刀菌（F.longipes）各17株（n=5）、4种（4 spp.）包括F.燕麦属（avenaceum）6个种（6 spp.）包括F.fujikuro）。利用TEF-1基因和组蛋白H3基因的DNA序列构建了分子遗传树，并分析了该物种的染色体数目与遗传的关系。结果表明，产毒素镰刀菌属真菌的产毒能力较强。在两个独立的路线中演化，即n[大于或等于]12→n=8和n[大于或等于]12→n=4。构成n=4的染色体可能是由祖先的小染色体融合而成（染色体融合假说）.为了验证染色体融合假说，对F.禾谷镰刀菌（F. graminearum）的染色体DNA。proliferatum作为探针。在本研究中，F. proliferatum位于F.禾谷早熟禾

In this research project, molecular cytogenetic study was carried out on the karyotypes and chromosomes of mycotoxin-producing Fusarium spp. such as F.graminearum, and the data were analyzed in relation to the evolution of this group. The main results obtained are as follows.1. The detailed karyotypes including chromosome number (n=4) and morphological feature of chromosomes were determined for the standard strains PH-1 and 00-676 that were used for genome sequencing project. Each chromosome was corresponded to the specific genetic linkage group.2. Both cytological and electrophoretic karyotypes were determined for 21 species (35 strains) collected from 12 countries. The data showed that each species has constant, species-specific chromosome number and also that species can be classified into three groups based on the chromosome number, that is, groups with n=4 (9 spp. including F graminearum), n=5 (17 equiseti and F.longipes), n=8 (4 spp. including F. avenaceum), and n=12 (6 spp. including F.fujikuro), respectively.3. Molecular phylogenic trees were constructed using DNA sequences of TEF-1 and histone H3, and relationships between phylogeny and chromosome number of the species was analyzed. The results indicated that the mycotoxin-producing Fusarium spp. evolved in the two independent routes, namely, n【greater than or equal】12→n=8 and n【greater than or equal】12→n=4. Probably, chromosomes constituting n=4 was formed by fusion of small chromosomes of the ancestor (chromosome fusion hypothesis).4. In order to prove chromosome fusion hypothesis, chromosome painting FISH was performed to the metaphase chromosomes of F. graminearum using chromosomal DNAs of F. proliferatum as probes. In this analysis, 0.7-Mb chromosome of F. proliferatum was allocated to the distal region of chromosome 4 of F. graminearum.