In vitro and in vivo antifungal activity of Cymbopogon citrates essential oils from different climate conditions against Botrytis cinerea

Essential oils (EOs) are natural, volatile and aromatic substances extracted from some specific plants. EOs are the secondary metabolite of plants and usually varies with different plants and climate conditions, even in the same plant species but different climate conditions. The antifungal properties of EOs from medicinal as well as other edible plants have been recognized for very long time. Cymbopogon citratus oil, which is used as a food flavoring agent, possesses a broad spectrum of in vitro antifungal activities attributed to the high content of mono-terpenoids such as alpha-Citral and beta-Citral. In this study we focused on the changes of components of EOs in C. citratus growing in different climate conditions and their antifungal activities as well. The samples of C. citrates, fresh and dried, obtained from five different climate conditions in Southern and Southwestern China (Kunming, Jinghong, Fangchenggang, Zengcheng, Yuxi). The C. citrates EOs were extracted by the steam distillation method and analyzed by gas chromatography coupled with mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID). The results showed that the content of alpha-Citral was the highest in ten EOs. Fresh and dried C. citratus EOs accounted for 38.7% and 43.3% in Zengcheng, respectively. However, fresh and dried C. citratus EOs accounted for 24.2% and 23.1% in Kunming. The effects of C. citratus EOs from different climate conditions against Botrytis cinerea were studied. All EOs had good inhibition against mycelial growth and spore germination of B. cinerea in vitro. At 15.63 mg/L, the inhibition of mycelial growth with the dried C. citrates EO from Zengcheng was significantly greater than that with the other EOs, with an inhibitory effect of 96.3%. It completely inhibited the mycelial growth of B. cinerea at 31.25 mg/L. Ten EOs also had good inhibitory effects on the rotten area of cherry tomatoes infected by B. cinerea in vivo. At 125 mg/L, the decay area of cherry tomatoes was reduced by more than 90%. The results indicated that the constituents in EOs of C. citrates are different from one growing place to another. The EOs of C. citrates may be considered as po-tential candidates to protect postharvest fruit from B. cinerea damage.