Biocontrol activity and potential mechanism of volatile organic compounds from Aspergillus niger strain La2 against pear Valsa canker

Abstract BACKGROUND Valsa pyri ‐caused pear Valsa canker is one of the most destructive diseases of pear, causing severe yield and economic lost. Volatile organic compounds (VOCs) from endophytes take important roles in the regulation of plant disease. In the present study, we investigated the biocontrol activity of endophytic fungus Aspergillus niger strain La2 and its antagonistic VOCs against pear Valsa canker. RESULTS The strain La2 exhibited obvious inhibitory effect against V. pyri . Colonization assay suggested that strain La2 could colonize to complete its life cycle on pear twigs. The symptoms of pear Valsa canker were weakened on detached pear twigs after treatment with strain La2. In addition, VOCs from strain La2 also significantly suppressed the mycelial growth of V. pyri . Based on the results of headspace solid‐phase microextraction/gas chromatography‐mass spectrometry (HS‐SPME‐GC‐MS) analysis, 6 possible VOCs produced by strain La2 were detected, and 2,4‐di‐tert‐butylphenol and 4‐methyl‐1‐pentanol were the main antagonistic VOCs of strain La2 according to its antagonism effect on pear Valsa canker in vitro and in vivo . Further results showed that 4‐methyl‐1‐pentanol could destroy the V. pyri hypha structure and cell membrane integrity. Importantly, the activities of pear defense‐related enzymes (PPO, PAL and SOD) were enhanced after 4‐methyl‐1‐pentanol treatment in pear twigs, implying that 4‐methyl‐1‐pentanol might induce plant disease resistance response. CONCLUSION A. niger strain La2 and its VOCs compounds 2,4‐di‐tert‐butylphenol and 4‐methyl‐1‐pentanol offer the potential as novel biocontrol agents of pear Valsa canker. This article is protected by copyright. All rights reserved.