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

Abstract

Bacillus volatiles to control plant nematodes is a topic of great interest among researchers due to its safe and environmentally friendly nature. Bacillus strain GBSC56 isolated from the Tibet region of China showed high nematicidal activity against M. incognita, with 90% mortality as compared with control in a partition plate experiment. Pure volatiles produced by GBSC56 were identified through gas chromatography and mass spectrometry (GC-MS). Among 10 volatile organic compounds (VOCs), 3 volatiles, i.e., dimethyl disulfide (DMDS), methyl isovalerate (MIV), and 2-undecanone (2-UD) showed strong nematicidal activity with a mortality rate of 87%, 83%, and 80%, respectively, against M. incognita. The VOCs induced severe oxidative stress in nematodes, which caused rapid death. Moreover, in the presence of volatiles, the activity of antioxidant enzymes, i.e., SOD, CAT, POD, and APX, was observed to be enhanced in M. incognita-infested roots, which might reduce the adverse effect of oxidative stress-induced after infection. Moreover, genes responsible for plant growth promotion SlCKX1, SlIAA1, and Exp18 showed an upsurge in expression, while AC01 was downregulated in infested plants. Furthermore, the defense-related genes (PR1, PR5, and SlLOX1) in infested tomato plants were upregulated after treatment with MIV and 2-UD. These findings suggest that GBSC56 possesses excellent biocontrol potential against M. incognita. Furthermore, the study provides new insight into the mechanism by which GBSC56 nematicidal volatiles regulate antioxidant enzymes, the key genes involved in plant growth promotion, and the defense mechanism M. incognita-infested tomato plants use to efficiently manage root-knot disease.

Foliar melatonin stimulates cotton boll distribution characteristics by modifying leaf sugar metabolism and antioxidant activities during drought conditions

“…The Step One Real‐Time PCR System (Applied Biosystems) was used for RT‐qPCR analysis. The SYBR Green (Takara Bio), which emits fluorescence to cDNA, was used as a detector (Ayaz et al 2021). The value of the fluorescence was noted at the threshold cycle (C).…”

5-Methoxyindole, a Chemical Homolog of Melatonin, Adversely Affects the Phytopathogenic Fungus Fusarium graminearum

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Nematicidal Effects of Volatile Organic Compounds from Microorganisms and Plants on Plant-Parasitic Nematodes

“…and B. xylophilus (Table 1). Pseudomonas koreensis T3GI1 3-methoxy-2,5-dimethyl pyrazine, 1-undecene, dimethyl disulfide [16] Pseudomonas monteilii T8GH4 1-undecene, dimethyl disulfide, 2-undecanone [16] Pseudomonas soli T13GI4 1-undecene, dimethyl disulfide [16] Comamonas sediminis T13GI2 1-undecene, dimethyl disulfide [16] Variovorax paradoxus T1GI1 dimethyl disulfide [16] Bacillus atrophaeus GBSC56 dimethyl disulfide, methyl isovalerate, 2-undecanone [17] Bacillus cereus Bc-cm103 dimethyl disulfide, S-methyl ester butanethioic acid [18] Bacillus megaterium YFM3.25 benzeneacetaldehyde, 2-nonanone, decanal, 2-undecanone, dimethyl disulphide [19] Bacillus mycoides R2 styrene [20] Lysinibacillus mangiferahumi M-GX18 T 2-octanol, cyclohexene, 3-chloro-4-fluoroben-zaldehyde, dibutyl phthalate, 2-nitro-2-chloropropane, dimethachlore, dimethyl disulfide [21] Paenibacillus polymyxa KM2501-1 furfural acetone, 2-decanol, 2-undecanone, 2-undecanol 2-decanone, 2-nonanol [22] Pseudochrobactrum saccharolyticum AM180484 dimethyl disulfide, S-methyl thiobutyrate, acetophenone, ethyl 3,3-dimethylacrylate, nonan-2-one [14] Proteus hauseri JN092591 dimethyl disulfide, S-methyl thiobutyrate, nonan-2-one, 1-methoxy-4-methylbenzene [14] Wautersiella falsenii AM238687 dimethyl disulfide, S-methyl thiobutyrate, nonan-2-one, 1-methoxy-4-methylbenzene, butyl isovalerate [14] Arthrobacter nicotianae JQ071518 dimethyl disulfide, S-methyl thiobutyrate, acetophenone [14] Achromobacter xylosoxidans AF411019 dimethyl disulfide, S-methyl thiobutyrate, acetophenone, nonan-2-one, 1-methoxy-4-methylbenzene [14] Virgibacillus dokdonensis MCCC 1A00493 acetaldehyde, dimethyl disulfide, 4-vinylphenol [23,24] Duddingtonia flagrans cyclohexanamine, cyclohexanone, cyclohexanol [25] Fusarium oxysporum 21 2-methylbutyl acetate, 3-methylbutyl acetate, ethyl acetate, 2-methylpropyl acetate, caryophyllene [26,27] Meloidogyne javanica Pseudomonas koreensis T3GI1 Daldinia cf. concentrica 3-methyl-1-butanol, (±)-2-methyl-1-butanol, 4-heptanone, isoamyl acetate [28] Meloidogyne hapla Metarhizium brunneum 1-octen-3-ol, 3-octanone [29]…”

“…In this study, nematicidal VOCs from Bacillus dominated. Bacillus atrophaeus GBSC56, derived from plant-growth-promoting rhizobacteria, from the Tibet region of China, was isolated [17]. Among the VOCs produced by GBSC56, dimethyl disulfide, methyl isovalerate, and 2-undecanone exhibited strong nematicidal activity.…”