Data from: Enhanced diversity and aflatoxigenicity in interspecific hybrids of Aspergillus flavus and Aspergillus parasiticus

Aspergillus flavus and A. parasiticus are the two most important aflatoxin-producing fungi responsible for the contamination of agricultural commodities worldwide. Both species are heterothallic and undergo sexual reproduction in laboratory crosses. Here we examine the possibility of interspecific matings between A. flavus and A. parasiticus. These species can be distinguished morphologically and genetically, as well as by their mycotoxin profiles. Aspergillus flavus produces both B aflatoxins and cyclopiazonic acid (CPA), B aflatoxins or CPA alone, or neither mycotoxin; Aspergillus parasiticus produces B and G aflatoxins or the aflatoxin precursor O-methylsterigmatocystin, but not CPA. Only four of forty-five attempted interspecific crosses between opposite mating types of A. flavus and A. parasiticus were fertile and produced viable ascospores. Single ascospore strains from each cross were shown to be recombinant hybrids using multilocus genotyping and array comparative genome hybridization. Conidia of parents and their hybrid progeny were haploid and predominantly monokaryons and dikaryons based on flow cytometry. Multilocus phylogenetic inference showed that experimental hybrid progeny were grouped with naturally occurring A. flavus L strain and A. parasiticus. Higher total aflatoxin concentrations in some F1 progeny strains compared to midpoint parent aflatoxin levels indicate synergism in aflatoxin production; moreover, three progeny strains synthesized G aflatoxins that were not produced by the parents, and there was evidence of allopolyploidization in one strain. These results suggest that hybridization is an important diversifying force resulting in the genesis of novel toxin profiles in these agriculturally important fungi.

黄曲霉（Aspergillus flavus）与寄生曲霉（Aspergillus parasiticus）是全球范围内导致农产品污染的两类最重要的产黄曲霉毒素真菌。二者均为异宗配合真菌，可在实验室杂交组合中完成有性生殖。本研究旨在探究黄曲霉与寄生曲霉之间发生种间交配的可能性。这两个物种可通过形态学、遗传学特征以及真菌毒素谱加以区分：黄曲霉可产生B族黄曲霉毒素与环匹阿尼酸（cyclopiazonic acid, CPA），或仅产生B族黄曲霉毒素、环匹阿尼酸，亦或不产生任何一类真菌毒素；寄生曲霉则可产生B族与G族黄曲霉毒素，或黄曲霉毒素前体O-甲基柄曲霉素，但无法产生环匹阿尼酸。在针对黄曲霉与寄生曲霉相反交配型开展的45组种间杂交尝试中，仅4组杂交可育并产生了有活力的子囊孢子。通过多位点基因分型与阵列比较基因组杂交（array comparative genome hybridization）分析，各杂交组合的单孢子菌株均被证实为重组杂交菌株。流式细胞术检测结果显示，亲本及其杂交后代的分生孢子均为单倍体，且主要以单核体与双核体形式存在。多位点系统发育推断结果表明，本实验获得的杂交后代可与自然存在的黄曲霉L株及寄生曲霉聚为同一分支。部分F1代杂交菌株的总黄曲霉毒素浓度相较于亲本平均水平更高，表明黄曲霉毒素合成存在协同效应；此外，有3株杂交后代合成了亲本无法产生的G族黄曲霉毒素，且其中1株菌株存在异源多倍体化的现象。本研究结果表明，种间杂交是一类重要的演化多样性驱动因素，可在这些具有重要农业价值的真菌中催生全新的真菌毒素谱。