苦瓜枯萎病菌的鉴定及其遗传多样性分析

 对分离获得的32株苦瓜枯萎病菌菌株进行形态学特征和寄主专化型测定, 结果表明, 测试的苦瓜枯萎病菌株均为尖孢镰刀菌苦瓜专化型 (Fusarium oxysporum f. sp. momordicae), 这些菌株可以侵染苦瓜和瓠瓜幼苗, 但不侵染其他葫芦科瓜类作物。对苦瓜枯萎病菌菌株的rDNA-ITS区 (ITS1、5.8S和ITS2)序列进行扩增测序, 结果显示其序列长度均为456 bp;聚类分析表明测序菌株与镰刀菌属中尖孢镰刀菌不同专化型的菌株聚为一群。利用RAPD标记技术分析苦瓜枯萎病菌的遗传多样性, 结果显示苦瓜枯萎病菌株与其他葫芦科瓜类作物枯萎病菌株间的遗传相似系数范围为0.59~0.99, 当遗传相似系数为0.85时, 供试的48个菌株分成10个类群 (G_1~10)。在RAPD聚类树中所有苦瓜枯萎病菌株聚在一个分支上 (G₁群), 菌株间的遗传相似系数范围为0.92~1.00, 具有较高的遗传相似性, 且菌株的聚群与地理来源存在一定的相关性。

Identification and genetic diversity of Fusarium oxysporum isolates from bitter gourd

Thirty-two Fusarium oxysporum isolates obtained from wilt bitter gourd in different regions of China were identified by morphology and formae speciales test. The results showed that all isolates were Fusarium oxysporum f. sp. momordicae (FOM). These isolates could only infect the seedlings of bitter gourd and bottle gourd, but not the other cucurbit species. Amplifying and sequencing results of the rDNA-ITS of isolates showed that the total length of rDNA-ITS (ITS1, 5.8S and ITS2) of FOM isolate was 456 base pairs. The clustering analysis of rDNA-ITS indicated that FOM and F. oxysporum f. spp. isolates could be gathered into one group. Meanwhile the results of the genetic diversity analysis with RAPD molecular marker showed that the genetic similarity coefficient of FOM isolates and the other formae speciales of F. oxysporum isolates from cucurbit hosts was ranging from 0.59 to 0.99; forty-eight isolates could be divided into ten RAPD groups (G_1-10) when the genetic similarity coefficient reached 0.85. In RAPD dendrogram, all the FOM isolates were gathered into one phylogenetic branch (group G₁) with the genetic similarity coefficient ranged from 0.92 to 1.00, which indicated a high genetic similarity existed in these isolates, and classification of phylogenetic group was related to geographic origin in some extents.