Biocontrol Potentials of Antimicrobial Peptide Producing Bacillus Species: Multifaceted Antagonists for the Management of Stem Rot of Carnation Caused by Sclerotinia sclerotiorum

S Vinodkumar,V G Malathi,S Nakkeeran,P Renukadevi

doi:10.3389/fmicb.2017.00446

S Vinodkumar, V G Malathi + Show 2 more

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https://doi.org/10.3389/fmicb.2017.00446

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Abstract

Bacillus species are widely exploited as biocontrol agents because of their efficiency in impeding various plant pathogens with multifaceted approach. In this study, Bacillus species were isolated from rhizosphere of various plants viz., carnations, cotton, turmeric, and bananas in Tamil Nadu state of India. Their potential to control the mycelial growth of Sclerotinia sclerotiorum was assessed in vitro by dual plate and partition plate techniques. B. amyloliquefaciens strain VB7 was much effective in inhibiting mycelial growth (45% inhibition of over control) and sclerotial production (100%). PCR detection of AMP genes revealed that B. amyloliquefaciens (VB7) had a maximum of 10 diverse antibiotic biosynthesis genes, namely, ituD, ipa14, bacA, bacD, bamC, sfP, spaC, spaS, alba, and albF, that resulted in production of the antibiotics iturin, bacilysin, bacillomycin, surfactin, subtilin, and subtilosin. Further, metabolites from B. amyloliquefaciens strains VB2 and VB7, associated with inhibition of S. sclerotiorum, were identified as phenols and fatty acids by gas chromatography mass spectrometry (GC-MS). Delivery of bacterial suspension of the effective strains of Bacillus spp. as root dip was found promising for the management of stem rot of cultivated carnations. Minimal percent disease incidence (4.6%) and maximum plant growth promotion was observed in the plants treated with B. amyloliquefaciens (VB7).

Highlights

IntroductionCarnation (Dianthus caryophyllus L.) is important cut flower with greater stipulation in the global market because of its variety of colors
Results revealed that application of B. amyloliquefaciens (VB7) by root dip followed by soil drenching at 0.5% (5 ml/l) resulted in a minimal stem rot incidence of 4.60%, which was reduced 87.9% relative to the control
We identified effective antagonists with diverse AMP genes that aid in curtailing stem rot of carnations by the production of diverse antimicrobial peptides, including both volatile and non-volatile antimicrobial compounds

Summary

Introduction

Carnation (Dianthus caryophyllus L.) is important cut flower with greater stipulation in the global market because of its variety of colors. Major states involved in floriculture business in India are Tamil Nadu (55,000 ha area), Karnataka (30,600 ha area) and West Bengal (24,900 ha). Total cut flower production in India during 2013–2014 is 5,48,000 MT. Total production of carnations allover India is 6,590 MT. Assam ranks first in carnation production in India with 1,320 MT (Indian Horticulture Database, 2014). Stem rot caused by Sclerotinia sclerotiorum (Lib.)

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