香蕉上的镰孢菌种类及其系统发育关系(英文)

镰孢菌属真菌是香蕉上的重要病原菌,主要引起香蕉枯萎病以及香蕉冠腐病,在我国已明确引起香蕉枯萎病的病原为尖孢镰孢古巴专化型 Fusarium oxysporum f. sp. cubense(FOC)1号和4号生理小种,但是引起香蕉冠腐病的镰孢菌种类还未明确。为了解香蕉上镰孢菌在种间及种内水平上的多样性,2008–2011 年间作者从华南地区不同的水果市场及香蕉果园采集香蕉样品90份,分离得到143株镰孢菌。通过形态学观察及基于 EF-1α基因的系统进化分析鉴定出10种镰孢菌,即F. oxysporum、F. solani、F. camptoceras、F. pallidoroseum、F. stiloides、F. chlamydosporum、F.verticillioides、F. proliferatum、F. concentricum、F. sacchari,以及藤仓赤霉复合种(Gibberella fujikuroi species complex,GFC)中 3 个未定名的类群。轮纹镰孢 F. concentricum 及甘蔗镰孢 F.sacchari 是香蕉果实中最常见种,前菌为我国首次报道,后菌是首次报道与香蕉有关。对从香蕉上分离的藤仓赤霉复合种(GFC)及尖孢镰孢复合种(FOSC)的EF-1α序列进行了系统发育分析,其GFC中的27个菌株组成的单系群可分为7个不同的亚群,分别为 F.verticillioides、F. proliferatum、F. concentricum、F. sacchari 以及3个没有描述过的菌系 Fusarium sp. 1、Fusarium sp.2和 Fusarium sp.3;FOSC中的50个菌株形成2大分枝共12个谱系,分离自我国华南地区的21株尖孢镰孢形成7个谱系,其中 13株已知的香蕉枯萎病病原菌分布在3个谱系中,我国大陆的香蕉枯萎病病原菌菌株与来源于台湾地区及东南亚的菌株亲缘关系较近,FOC1号生理小种的遗传分化大于4号生理小种,FOC 1号生理小种与分离自香蕉果实上的尖孢镰孢菌的亲缘关系比与FOC 4号生理小种的亲缘关系更近。研究结果表明,我国香蕉上存在着丰富的镰孢菌种类,而且种内遗传多样性丰富。

The Fusarium species isolated from banana and their phylogenetic relationships

Fusarium species are important pathogens of banana, especially causing such serious diseases as Panama disease and crown rot disease. F. oxysporum f. sp. cubense race 1 (Foc1) and race 4 (Foc4) were reported as the pathogenic populations of Panama disease in China, but it has been confused with the Fusarium species of crown rot disease. In order to understand the Fusarium diversities associated with banana in both interspecific and intraspecific levels, 143 Fusarium isolates were cultured from 90 banana samples collected from fruit markets and banana orchards in South China in 2008–2011. Based on morphological observation and phylogenetic analyses with partial translation elongation factor-1 alpha (EF-1α) gene, ten Fusarium species were recognized, including F. oxysporum, F. solani, F. camptoceras, F. pallidoroseum, F. stiloides, F. chlamydosporum, F. verticillioides, F. proliferatum, F. concentricum, F. sacchari, and three undescribed taxa in Gibberella fujikuroi species complex (GFC). F. concentricum is newly recorded in China. F. sacchari is firstly reported from banana. F. concentricum and F. sacchari were the most common GFC species in banana fruits. Phylogenic analyses were conducted for GFC and the F. oxysporum species complex (FOSC). 27 partial EF-1α sequences of GFC strains were employed and seven clades were recognized, including F. verticillioides, F. proliferatum, F. concentricum, F. sacchari and three undescribed lineages recorded as Fusarium sp. 1, Fusarium sp. 2 and Fusarium sp. 3. 50 partial EF-1α sequences of FOSC were employed and their phylogenetic analysis generated two major clades and 12 monophyletic lineages, 21 South China isolates in seven lineages, and 13 pathogenic strains distributing in three of them. The phylogenetic studies showed that the pathogens of Panama disease in China Mainland were closely related to those from Southeast Asia and Taiwan, China and wider genetic differentiation were found among the race 1 strains than the race 4 strains. Race 1 was genetically closer to the isolates obtained from fruits as compared with race 4. It is concluded that more Fusarium species and genetic groups are associated with banana and show plentiful intraspecific diversity.