Comparative analysis across diverse plant species reveals superior antibiofilm efficacy and dose-dependency of root extracts compared to leaf extracts

Although both root- and leaf-derived plant extracts hold potential as antibiofilm agents, research has predominantly focused on leaf tissues. In this study, we systematically compared the antibiofilm efficacy of 158 root and 248 leaf extracts from 360 plant species across five concentrations (0.1, 0.25, 0.5, 1.0, and 2.0 g/l). As concentration increased, the biofilm control incidence (BCI) of root extracts rose from 68.4% to 94.3%, while leaf extracts showed a smaller increase, from 52.2% to 71.7%. Similarly, the biofilm control efficacy (BCE) of root extracts increased from 27.6% to 54.2%, whereas leaf extracts ranged from -2.7% to 16.2%. Bootstrapping analysis (10 000 iterations) confirmed significantly higher antibiofilm activity of root extracts at concentrations ≥ 0.5 g/l (P < 0.05). Paired comparisons of species with both extract types further demonstrated the consistent superiority of root extracts across all concentrations (bootstrapped, P < 0.05), despite interspecific variation at higher doses. Linear regression revealed a significantly steeper dose-response slope for root extracts (29.2 ± 2.4) than for leaf extracts (8.1 ± 2.8) (bootstrapped, P < 0.05), indicating a stronger concentration-dependent effect of root extracts. These results suggest that plant roots typically harbor more potent and/or diverse antibiofilm compounds than leaves, underscoring their untapped potential for biofilm control applications.