突脐孢属Brnl基因核苷酸序列比较及系统发育研究

对所有供试突脐孢菌株的Brnl基因(1，3，8-三羟基萘还原酶基因)扩增均获得PCR产物。序列比较表明：在种内各菌株间没有核苷酸序列长度变化，存在核苷酸序列简单代换；在种间核苷酸序列长度有变化，核苷酸的缺失或插入发生在内含子区；所有菌株编码区核苷酸序列长度相同；在种内水平氨基酸序列没有差别，显示出高度的保守性。利用最大简约法(Maximum Parsimony)和邻近结合法(Neighbor-joining)构建系统发育树，两个系统发育树的拓扑结构相似，不同种在不同的分支上。Brnl基因适合突脐孢属种级水平的分子系统学研究。

SEQUENCE COMPARISON AND PHYLOGENETIC ANALYSIS OF BRN1 GENES FROM EXSEROHIL UM SPECIES

We examined Brn1 genes and gene products in strains of Exserohilum spp. Amino acid sequences of the Brn1 gene products were consistent within species. Nucleotide sequence lengths were equal within species and base pair substitutions were identified. Variation appeared to be caused by insertions or deletions within intron regions. Coding region lengths for Brn1 genes were identical in all strains. Phylogenetic analysis of nucleotide sequences were conducted using maximum parsimony and neighbor-joining methods. Topologies of most parsimonious and neighbor-joining trees were similar and clearly distinguished species within Exserohilum. These results indicate that the Brn1 gene is suitable for species-level molecular systematics for the Exserohilum genus.