Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
BMC Mol Biol. 2019 Feb 11;20(1):4. doi: 10.1186/s12867-019-0121-3.
Woronin bodies are fungal-specific organelles whose formation is derived from peroxisomes. The former are believed to be involved in the regulation of mycotoxins biosynthesis, but not in their damage repair function. The hexagonal peroxisome protein (HexA or Hex1) encoded by hexA gene in Aspergillus is the main and the essential component of the Woronin body. However, little is known about HexA in Aspergillus flavus.
In this study, hexA knock-out mutant (ΔhexA) and complementation strain (ΔhexA) were produced using homologous recombination. The results showed that, ΔhexA and ΔhexA were successfully constructed. And the data analysis indicated that the colony diameter, stress sensitivity and the sclerotia formation of A. flavus were nearly not affected by the absence of HexA. Yet, the deletion of hexA gene reduced the production of asexual spores and lessened virulence on peanuts and maize seeds markedly. In addition, it was also found that there was a significant decrease of Aflatoxin B1 production in deletion mutant, when compared to wild type.
Therefore, it suggested that the hexA gene has an essential function in conidia production and secondary metabolism in A. flavus. The gene is also believed to be playing an important role in the invasion of A. flavus to the host.
Woronin 体是真菌特有的细胞器，其形成来源于过氧化物酶体。前者被认为参与调控真菌毒素的生物合成，但不参与其损伤修复功能。HexA 基因编码的六方过氧化物酶体蛋白（HexA 或 Hex1）是 Woronin 体的主要和必需成分。然而，关于黄曲霉中的 HexA 知之甚少。
在本研究中，利用同源重组技术构建了 hexA 敲除突变体（ΔhexA）和互补菌株（ΔhexA）。结果表明，成功构建了ΔhexA 和 ΔhexA。数据分析表明，HexA 的缺失对黄曲霉的菌落直径、应激敏感性和产菌核能力几乎没有影响。然而，hexA 基因的缺失显著降低了无性孢子的产生，明显降低了对花 生和玉米种子的毒力。此外，还发现与野生型相比，缺失突变体中黄曲霉毒素 B1 的产量显著降低。
因此，该研究表明 hexA 基因在黄曲霉产分生孢子和次级代谢中具有重要功能。该基因还被认为在黄曲霉对宿主的侵染中起着重要作用。
