Synergistic Effect of Two Peptaibols from Biocontrol Fungus <i>Trichoderma longibrachiatum</i> Strain 40418 on CO-Induced Plant Resistance

<i>Trichoderma longibrachiatum</i> is a filamentous fungus used as a biological control agent against different plant diseases. The multifunctional secondary metabolites synthesized by <i>Trichoderma</i>, called peptaibols, have emerged as key elicitors in plant innate immunity. This study obtained a high-quality genome sequence for the <i>T. longibrachiatum</i> strain 40418 and identified two peptaibol biosynthetic gene clusters using knockout techniques. The two gene cluster products were confirmed as trilongin AIV a (11-residue) and trilongin BI (20-residue) using liquid chromatography coupled with tandem mass spectrometry. Further investigations revealed that these peptaibols induce plant resistance to <i>Pseudomonas syringae</i> pv <i>tomato</i> (<i>Pst</i>) DC3000 infection while triggering plant immunity and cell death. Notably, the two peptaibols exhibit synergistic effects in plant-microbe signaling interactions, with trilongin BI having a predominant role. Moreover, the induction of tomato resistance against <i>Meloidogyne incognita</i> showed similarly promising results.