Abstract: This study investigated the effect of citral on mitochondrial morphology, adenosine triphosphate (ATP) content and the tricarboxylic acid (TCA) cycle in Geotrichum citri-aurantii. Scanning electron microscopy showed the mitochondria of G. citri-aurantii were distorted, collapsed and even ruptured after citral treatment, leading to leakage of intracellular ATP and a consequent increase in extracellular ATP. The activity of citrate synthase (CS), α-ketoglutarate dehydrogenase (α-KGDH), isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) as well as the content of citric acid, all of which are associated with the TCA cycle, decreased after citral treatment at its minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC). In short, citral can affect mitochondrial morphology and function in G. citri-aurantii, but the underlying mechanism needs to be further explored.

Key words: citral, Geotrichum citri-aurantii, mitochondrial morphology, ATP content, tricarboxylic acid cycle