LT1: a potential biocontrol agent for southern blight on .

Introduction: Southern blight, caused by , poses a serious threat to the cultivation of , a plant with significant medicinal value. The overreliance on fungicides for controlling this pathogen has led to environmental concerns and resistance issues. There is an urgent need for alternative, sustainable disease management strategies.

Methods: In this study, LT1 was isolated from the rhizosphere soil of diseased plants. Its biocontrol efficacy against LC1 was evaluated through a confrontation assay. The antimicrobial lipopeptides in the fermentation liquid of LT1 were identified using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS). The effects of LT1 on the mycelial morphology of LC1 were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Results: The confrontation assay indicated that LT1 significantly inhibited the growth of LC1, with an inhibition efficiency of 78.41%. MALDI-TOF-MS analysis detected the presence of bacillomycin, surfactin, iturin, and fengycin in the fermentation liquid, all known for their antifungal properties. SEM and TEM observations revealed that the mycelial and cellular structures of LC1 were markedly distorted when exposed to LT1.

Discussion: The findings demonstrate that LT1 has considerable potential as a biocontrol agent against LC1. The identified lipopeptides likely contribute to the antifungal activity, and the morphological damage to LC1 suggests a mechanism of action. This study underscores the importance of exploring microbial biocontrol agents as a sustainable alternative to chemical fungicides in the management of plant diseases. Further research into the genetic and functional aspects of LT1 could provide deeper insights into its biocontrol mechanisms and facilitate its application in agriculture.