Bacillus megaterium WL-3 Lipopeptides Collaborate Against Phytophthora infestans to Control Potato Late Blight and Promote Potato Plant Growth

Abstract

Oomycete <i>Phytophthora infestans</i> [(Mont.) de Bary] is the cause of potato late blight, a plant disease which poses a serious threat to our global food security and is responsible for huge economic losses worldwide. Lipopeptides produced by <i>Bacillus</i> species are known to be potent antibacterial compounds against many plant pathogens. In this study, we show that <i>Bacillus megaterium</i> WL-3 has an antagonistic effect against potato late blight. Electrospray ionization mass spectrometry (ESI-MS) revealed that lipopeptides derived from the WL-3 strain contained three subfamilies, surfactin (C₁₃ - C₁₅), Iturin A (C₁₄ - C₁₆), and Fengycin A (C₁₅ - C₁₉). The Iturin A and Fengycin A lipopeptide families were each confirmed to have anti-oomycete effects against <i>P. infestans</i> mycelium growth as well as obvious controlling effects against potato late blight in greenhouse experiments and field assays. Furthermore, Iturin A and Fengycin A were able to promote plant photosynthetic efficiency, plant growth, and potato yield. Most importantly, the combination of Iturin A and Fengycin A (I + F) was superior to individual lipopeptides in controlling potato late blight and in the promotion of plant growth. The results of this study indicate that <i>B. megaterium</i> WL-3 and its lipopeptides are potential candidates for the control of late blight and the promotion of potato plant growth.