Fig. 6

Correlation analysis between microbial flora and metabolites of filler tobacco leaves. A Load map of microbial flora and metabolite prediction model based on O2PLS; B Heat map of correlation between microbial flora with VOCs and FAAs (VOCs and FAAs were screened based on O2PLS), blue represents positive correlation, red represents negative correlation; Significant correlations were expressed by *, * *, and * * *, which were p < 0.05, p < 0.01 and p < 0.001, respectively. C Pearson’s correlation coefficient (|r|> 0.7, p < 0.05) indicates robust correlations. The different color circles refer to bacteria, fungi, volatile organic compounds, and free amino acids, respectively. VOCs23, VOCs43, VOCs81, VOCs115 and VOCs143 denote solanone, isophorone, durene, (-)-alpha-terpineol, and 2,3'-bipyridine, respectively. The red lines refer to positive (r > 0.7) correlations. The size of nodes indicates the degree of connections