Effect of Shatangju (Citrus reticulataBlanco) Essential Oil on Spore Germination and Mycelium Growth ofPenicillium digitatumandP. italicum

The chemical composition of the essential oil obtained from the peel of Shatangju (Citrus reticulata Blanco) was analyzed by gas chromatography and gas chromatography/mass spectrometry (GC-MS). Thirty seven components were identified. The hydrocarbon monoterpenes with 88.89 % (w/w) of the total essential oil were the principal compound groups. Among which, limonene was observed dominant (77.22%), followed by β-myrcene (3.7 %), β-phellandrene (2.75 %), ocimene (2.61 %), linalool (2.33 %), α-pinene (1.57 %), 1-octanol (1.52 %), decanal (1.23 %), 4-undecene (1.03 %) and other minor components. The spore germination and mycelium growth of P. italicum and P. digitatum could be mildly stimulated by the essential oil or did not show any obvious effect at a low concentration (≤2.5 μl/ml), while could be strongly inhibited at a higher concentration. In contrast, the spore germination and mycelium growth of P. sclerotiorum and P. expansum were strongly inhibited by the Shatangju essential oil even at a low concentration of 0.5 μl/ ml. In addition, treatment with 20 μl/ml Shatangju essential oil could lead to a distinct irregular mycelium growth of P. digitatum and P. italicum, as well as to a reduction in cytoplasmic content of P. italicum.