Antifungal

Penicillium expansum

Biology

Antimicrobial

Inflorescence

Essential oil

Melaleuca

EC50

Biochemistry

Botany

Food science

Postharvest

Bract

In vitro

Microbiology

Tea tree oil

Horticulture

Melaleuca alternifolia

Medicine

Chemistry

Traditional medicine

Penicillium expansum is a cosmopolitan pathogen that can cause several damages to fruit crops, leading to an intense search for alternative methods for its control. This study aimed to assess the antimicrobial effects of Cymbopogon martinii, Illicium verum and Melaleuca alternifolia essential oils (EOs) against P. expansum, elucidating their mechanisms of action. The P. expansum conidia were exposed to the vapor phase of the EOs, in different concentrations (0.125 g L−1 to 1 g L−1), for different times (1–24 h). Their fungicidal/fungistatic effects assessed in vitro, and their mechanisms of action investigated through DNA, protein and glucose extravasation, lipid damage, reactive oxygen species accumulation and antioxidant activity. In situ, their antimicrobial activities were assessed on apples cv. Fuji. The EOs inhibited 100% of fungal germination after 4 h at 0.25 g L−1, causing damages to the plasma membrane, leading to DNA (∼69.27 ng), protein (∼39.28 μg) and glucose (∼5.77 mg) leakage, and lipid damage (∼7.72 pmol of TBARS). Although a high efficiency to inhibit P. expansum through an antioxidant activity was observed, a minor effect was observed in situ, indicating different interactions between EOs and the environment, which can reduce their antimicrobial activities.

Antifungal activity of palmarosa (Cymbopogon martinii), tea tree (Melaleuca alternifolia) and star anise (Illicium verum) essential oils against Penicillium expansum and their mechanisms of action