Suppression of Sclerotinia sclerotiorum by the Induction of Systemic Resistance and Regulation of Antioxidant Pathways in Tomato Using Fengycin Produced by Bacillus amyloliquefaciens FZB42

Abstract

Lipopeptides from Bacillus species exhibit promising biological control activity against plant pathogens. This study aimed to explore the potential of purified fengycin to induce systemic resistance in tomato against Sclerotinia sclerotiorum. Bacillus amyloliquefaciens FZB42, its mutant AK1S, and their corresponding metabolites showed in vitro inhibition of S. sclerotiorum mycelium. Fengycin derived from an AK1S mutant was purified and identified through HPLC and MALDI-TOF-MS, respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed structural deformities in the fungal mycelium. Moreover, fengycin induced the accumulation of reactive oxygen species (ROS) in S. sclerotiorum mycelium and downregulated the expression of ROS-scavenging genes viz., superoxide dismutase (SsSOD1), peroxidase (SsPO), and catalase (SsCAT1) compared to the untreated control. Furthermore, the lesion size was dramatically reduced in fengycin-treated tomato plants compared to plants infected with S. sclerotiorum only in a greenhouse experiment. Additionally, the transcriptional regulation of defense-related genes GST, SOD, PAL, HMGR, and MPK3 showed the highest upsurge in expression at 48 h post-inoculation (hpi). However, their expression was subsequently decreased at 96 hpi in fengycin + S. sclerotiorum treatment compared to the plants treated with fengycin only. Conversely, the expression of PPO increased in a linear manner up to 96 hpi.

Nematicidal Volatiles from Bacillus atrophaeus GBSC56 Promote Growth and Stimulate Induced Systemic Resistance in Tomato against Meloidogyne incognita

“…Exposure to toxic compounds that elicit ROS production resulted in abnormal cell homeostasis and finally death [ 36 , 37 ]. The current results show that MIV, 2-undecanone (2-UD) and dimethyl disulfide (DMDS) with strong nematicidal activity-induced ROS in nematodes.…”

Elicitors of Plant Immunity Triggered by Beneficial Bacteria

“…Induction of systemic resistance and/or plant defenses by other CLPs produced by biocontrol bacilli has also been occasionally reported. In tomato and grapevine, fengycin triggered ISR against B. cinerea and Plasmopara viticola ( Farzand et al, 2019 ; Li et al, 2019 ), while CLPs from the iturin group ( Figure 1-3 ) were shown to have a similar role in strawberry ( Yamamoto et al, 2015 ), cotton ( Han et al, 2015 ), grapevine ( Farace et al, 2015 ) and Arabidopsis ( Wu et al, 2018 ). Additionally illustrating the dependence of CLP-mediated ISR on the plant organ, iturin showed bioactivity on roots at concentration of 50 μM, whereas it was active already at 1–10 μM when applied on leaves ( Han et al, 2015 ; Kawagoe et al, 2015 ; Yamamoto et al, 2015 ; Park et al, 2016 ).…”

Isolation and Characterization of Fengycins Produced by Bacillus amyloliquefaciens JFL21 and Its Broad-Spectrum Antimicrobial Potential Against Multidrug-Resistant Foodborne Pathogens

“…To date, the active mechanism of fengycins is less well known compared with iturins and surfactins. The possible mechanism for the antifungal activity of fengycins is that they interact with sterol and phospholipid molecules in membranes and thus alter the structure and permeability of the fungal cell membrane (Farzand et al, 2019;Hanif et al, 2019). However, the mechanism of interaction may vary and depend on the structural features of fengycins and pathogen species (Kaur et al, 2017;Sarwar et al, 2018).…”