中国部分省份苹果轮纹病菌及相关类群的系统学关系

Phylogenetic relationships of Botryosphaeria dothidea and its allies in China

【目的】对苹果轮纹病菌(Botryosphaeria dothidea)及其相关类群的rDNA-ITS序列进行分析,探讨他们之间的系统学关系,为进一步研究其系统发育和演化提供理论依据。【方法】对来源于陕西、山西、山东、河南及四川5个省份的113株苹果轮纹病菌和2株梨轮纹病菌的rDNA-ITS区段直接测序,经GenBank同源性检索比对(BLASTn)及DnaSP 4.0软件分析后,结合GenBank下载序列构建系统发育的邻接树和最大简约树,同时计算遗传距离和序列核苷酸差异数。【结果】115株供试菌株分为9个单倍型(Hap_1～Hap_9),其中Hap_7(B.obtusa)来源于山西省;Hap_9(苹果壳色单隔孢溃疡病菌,B.stevensii)来源于四川省;其余单倍型均为B.dothidea,其中Hap_1的出现频率最高,包含86株分离株。邻接法和最大简约法分析结果显示,用于构建发育树的序列均形成了3个大的聚类组。聚类组Ⅰ包含B.obtusa、B.rhodina(柑橘葡萄座腔菌)和B.stevensii等3个种,其中B.obtusa和B.rhodina各自独立聚为一支,而B.stevensii全部序列分为3支。聚类组Ⅱ包含2个分支:其中B.lutea单独聚为一支;B.ribis(茶麃子葡萄座腔菌)和B.parva亲缘关系较近,共同聚为一支。聚类组Ⅲ由B.dothidea和贝伦格葡萄座腔菌(B.berengeriana)共同构成,支持B.dothidea与B.berengeriana为同物异名的观点。遗传距离及序列核苷酸差异数显示,B.dothidea与其他种间的遗传距离在4.91%～7.57%,序列核苷酸差异数为31～54bp;B.dothidea不同单倍型之间的遗传距离为0.19%～1.93%,序列核苷酸差异数为1～10bp。【结论】B.stevensii显示出了复合种的特性,其分类地位还有待于进一步研究。B.dothidea与其他相似种的亲缘关系较远,且在B.dothidea种内存在核苷酸序列的分化,但分化程度较低。B.dothidea不同地理来源的菌株之间存在差异,但地理分化特征不明显。

【Objective】 Phylogenetic relationships of Botryosphaeria dothidea and its allies in China were investigated based on analyses of rDNA-ITS sequences.Then the theoretical basis for the further study of their system development and evolution could be got.【Method】 113 apple ring rot isolates and 2 pear ring rot isolates from Shaanxi,Shanxi,Shandong,Henan and Sichuan province were used for direct rDNA-ITS sequencing.After BLASTn and analysis by the DnaSP 4.0 software,MP tree and NJ tree were constructed.At the same time genetic distances and number of different sites of rDNA-ITS sequences were calculated.【Result】 115 isolates were divided into 9 haplotypes（Hap_1-Hap_9）.Hap_7（B.obtusa） was from Shanxi province.And Hap_9（B.stevensii） was from Sichuan province.Other haplotypes were B.dothidea.In addition,Hap_1 which contained 86 isolates had the highest frequency.Phylogenetic analysis showed that all sequences were divided into three groups.Three species,which were B.obtusa,B.rhodina and B.stevensii,formed groupⅠ,in which,B.obtusa formed an exclusive clade and also B.rhodina.Then B.stevensii clustered into three clades.Group Ⅱ had two clades：an exclusive clade was formed by B.lutea;B.ribis and B.parva were clustered together for their near genetic relationship.Group Ⅲ was constituted by B.dothidea and B.berengeriana,supporting the idea that they are synonymous.The analysis of genetic distances and different sequence sites showed the genetic distances between B.dothidea and its allies were 4.91%-7.57% and the different sequence sites were 31-54 bp.Moreover,the genetic distances between different haplotypes were 0.19%-1.93% and the different sequence sites were 1-10 bp.【Conclusion】 B.stevensii showed the characteristic of aggregate species and further study should be done.B.dothidea and its allies had far genetic relationship.And there were sequence of nucleotides differentiations within B.dothidea but the differentiation degree was low.There were differences among isolates from different geographical origins but the characteristics of their geographic differentiations were not obvious.