Volatile Organic Compound Profile Changes in Lentinula edodes Pileus Following Trichoderma atroviride Inoculation

This study explored disease symptom development and changes in relative volatile organic compound (VOC) profiles after inoculation of Trichoderma atroviride onto Lentinula edodes pilei. Phylogenetic analyses based on ITS and tef1 sequences supported identification of the inoculated strain as T. atroviride. Inoculation caused surface depression and browning, while discoloration extended from the surface into internal tissues. At 3 days after inoculation, the inoculated strain was re-isolated from T1-T3 tissues, confirming the presence of viable fungi at all sampling positions. Relative VOC profiles were compared among untreated pilei, wound-treated samples, T. atroviride cultures (TA), and samples collected from different positions after inoculation (T1-T3). PCA and heatmap analyses revealed descriptive VOC variation among treatment groups and T1-T3, although no individual VOCs differed significantly among T1-T3 after FDR correction. 6-Pentyl-2H-pyran-2-one showed the highest relative peak area percentage in TA, whereas 2(3H)-naphthalenone was consistently detected only in TA. In inoculated pilei, ylangene was detected at all positions, whereas γ-muurolene, α-muurolene, 1-naphthalenol, 3-octanone, and 1,2,4-trithiolane showed different detection patterns and relative peak area percentages among T1-T3. These findings provide a basis for quantitative validation of inoculation-associated VOC changes and potential spatial variation within the pileus.