Dipartimento di Biologia Ambientale, Università La Sapienza, Roma, Italy.
PLoS One. 2013 Jul 19;8(7):e68735. doi: 10.1371/journal.pone.0068735. Print 2013.
Aspergillus flavus is a cosmopolitan fungus able to respond to external stimuli and to shift both its trophic behaviour and the production of secondary metabolites, including that of the carcinogen aflatoxin (AF). To better understand the adaptability of this fungus, we examined genetic and phenotypic responses within the fungus when grown under four conditions that mimic different ecological niches ranging from saprophytic growth to parasitism. Global transcription changes were observed in both primary and secondary metabolism in response to these conditions, particularly in secondary metabolism where transcription of nearly half of the predicted secondary metabolite clusters changed in response to the trophic states of the fungus. The greatest transcriptional change was found between saprophytic and parasitic growth, which resulted in expression changes in over 800 genes in A. flavus. The fungus also responded to growth conditions, putatively by adaptive changes in conidia, resulting in differences in their ability to utilize carbon sources. We also examined tolerance of A. flavus to oxidative stress and found that growth and secondary metabolism were altered in a superoxide dismutase (sod) mutant and an alkyl-hydroperoxide reductase (ahp) mutant of A. flavus. Data presented in this study show a multifaceted response of A. flavus to its environment and suggest that oxidative stress and secondary metabolism are important in the ecology of this fungus, notably in its interaction with host plant and in relation to changes in its lifestyle (i.e. saprobic to pathogenic).
黄曲霉是一种世界性的真菌，能够对外界刺激做出反应，并改变其营养行为和次生代谢产物的产生，包括致癌物质黄曲霉毒素（AF）。为了更好地理解这种真菌的适应性，我们在模拟不同生态位的四种条件下，研究了真菌内部的遗传和表型反应，这些生态位从腐生生长到寄生生长不等。在这些条件下，我们观察到了初级和次级代谢物的全球转录变化，特别是在次级代谢物中，近一半的预测次级代谢物簇的转录发生了变化，以响应真菌的营养状态。在腐生和寄生生长之间发现了最大的转录变化，这导致了黄曲霉中超过 800 个基因的表达变化。真菌还对生长条件做出了反应，推测是通过分生孢子的适应性变化，导致它们利用碳源的能力存在差异。我们还研究了黄曲霉对氧化应激的耐受性，发现超氧化物歧化酶（sod）突变体和烷基氢过氧化物还原酶（ahp）突变体中的生长和次级代谢物发生了改变。本研究中提供的数据显示了黄曲霉对环境的多方面反应，并表明氧化应激和次级代谢物在该真菌的生态学中很重要，特别是在与宿主植物的相互作用以及与生活方式的变化（即腐生到病原）有关。
