Cladal relatedness among Aspergillus oryzae isolates and Aspergillus flavus S and L morphotype isolates
Cladal relatedness among Aspergillus oryzae isolates and Aspergillus flavus S and L morphotype isolates
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DOI：
10.1016/j.ijfoodmicro.2005.11.008
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发表时间：
2006-04-25
影响因子：
5.4
通讯作者：
Hua, SST
中科院分区：
文献类型：
--
作者：
Chang, PK;Ehrlich, KC;Hua, SST
黄曲霉是农作物黄曲霉毒素污染的主要病原。它的近亲米曲霉不产生黄曲霉毒素，已被广泛用于生产发酵食品。我们利用黄曲霉毒素生物合成基因簇中omtA基因的单核苷酸多态性和norB-cypA基因间区及其远端缺失作为系统发育信号，比较了A. oolzae分离株与A.和s型黄曲霉菌核分离株的系统发育。黄曲霉毒素产生能力和菌核大小也在分析中被加权。像黄芽孢杆菌一样，米芽孢杆菌分离物形成一个多系组合。在一个分支中，耳霉分离株与产氧性l型分离株的黄曲霉亚群惊人地相似。所有产氧s型分离株与产氧l型分离株的另一个亚群非常相似。由于无氧s型分离株极为罕见，我们假设s型分离株中黄曲霉毒素产量的减少可能伴随着l型菌核的变化。与米芽孢杆菌不同，所有的l型毒株在非b - cypa区都有1.0 kb的缺失。虽然稻瘟病菌分离株与s型一样，在norB-cypA区域有1.5 kb的缺失，但与s型黄曲霉分离株没有亲缘关系。我们的研究结果表明黄曲霉种群具有遗传多样性。米曲霉分离株可能来自某些抗氧性l型黄曲霉分离株。Elsevier B.V.出版
Aspergillus flavus is the main etiological agent for aflatoxin contamination of crops. Its close relative, A. oryzae, does not produce aflatoxins and has been widely used to produce fermented foods. We compared the phylogeny of A. oolzae isolates and L- and S-type sclerotial isolates of A. flavus using single nucleotide polymorphisms in the omtA gene in the aflatoxin biosynthesis gene cluster and deletions in and distal to the norB-cypA intergenic region as phylogenetic signals. Aflatoxin-producing ability and sclerotial size also were weighted in the analysis. Like A. flavus, the A. oryzae isolates form a polyphyletic assemblage. A. otyzae isolates in one clade strikingly resemble an A. flavus subgroup of atoxigenic L-type isolates. All toxigenic S-type isolates closely resemble another subgroup of atoxigenic L-type isolates. Because atoxigenic S-type isolates are extremely rare, we hypothesize that loss of aflatoxin production in S-type isolates may occur concomitantly with a change to L-type sclerotia. All toxigenic L-type isolates, unlike A. oryzae, have a 1.0 kb deletion in the not-B-cypA region. Although A. oryzae isolates, like S-type, have a 1.5 kb deletion in the norB-cypA region, none were cladally related to S-type A. flavus isolates. Our results show that A. flavus populations are genetically diverse. A. oryzae isolates may descend from certain atoxigenic L-type A. flavus isolates. Published by Elsevier B.V.