AUTHOR=Janahiraman Veeranan , Anandham Rangasamy , Kwon Soon W. , Sundaram Subbiah , Karthik Pandi Veeranan , Krishnamoorthy Ramasamy , Kim Kiyoon , Samaddar Sandipan , Sa Tongmin 

TITLE=Control of Wilt and Rot Pathogens of Tomato by Antagonistic Pink Pigmented Facultative Methylotrophic Delftia lacustris and Bacillus spp.

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.01626

DOI=10.3389/fpls.2016.01626

ISSN=1664-462X

ABSTRACT=<p>The studies on the biocontrol potential of pink pigmented facultative methylotrophic (PPFM) bacteria other than the genus <italic>Methylobacterium</italic> are scarce. In the present study, we report three facultative methylotrophic isolates; PPO-1, PPT-1, and PPB-1, respectively, identified as <italic>Delftia lacustris, Bacillus subtilis</italic>, and <italic>Bacillus cereus</italic> by 16S rRNA gene sequence analysis. Hemolytic activity was tested to investigate the potential pathogenicity of isolates to plants and humans, the results indicates that the isolates PPO-1, PPT-1, and PPB-1 are not pathogenic strains. Under <italic>in vitro</italic> conditions, <italic>D. lacustris</italic> PPO-1, <italic>B</italic>. <italic>subtilis</italic> PPT-1, and <italic>B</italic>. <italic>cereus</italic> PPB-1 showed direct antagonistic effect by inhibiting the mycelial growth of fungal pathogens; <italic>Fusarium oxysporum</italic> f. sp. <italic>lycopersici</italic> (2.15, 2.05, and 1.95 cm), <italic>Sclerotium rolfsii</italic> (2.14, 2.04, and 1.94 cm), <italic>Pythium ultimum</italic> (2.12, 2.02, and 1.92 cm), and <italic>Rhizoctonia solani</italic> (2.18, 2.08, and 1.98 cm) and also produced volatile inhibitory compounds. Under plant growth chamber condition methylotrophic bacterial isolates; <italic>D</italic>. <italic>lacustris</italic> PPO-1, <italic>B</italic>. <italic>subtilis</italic> PPT-1, and <italic>B. cereus</italic> PPB-1 significantly reduced the disease incidence of tomato. Under greenhouse condition, <italic>D</italic>. <italic>lacustris</italic> PPO-1, <italic>B</italic>. <italic>subtilis</italic> PPT-1, and <italic>B</italic>. <italic>cereus</italic> PPB-1 inoculated tomato plants, when challenged with <italic>F</italic>. <italic>oxysporum</italic> f. sp. <italic>lycopersici, S</italic>. <italic>rolfsii, P</italic>. <italic>ultimum</italic>, and <italic>R</italic>. <italic>solani</italic>, increased the pathogenesis related proteins (β-1,3-glucanase and chitinase) and defense enzymes (phenylalanine ammonia lyase, peroxidase, polyphenol oxidase, and catalase) on day 5 after inoculation. In the current study, we first report the facultative methylotrophy in pink pigmented <italic>D. lacustris, B</italic>. <italic>subtilis</italic>, and <italic>B</italic>. <italic>cereus</italic> and their antagonistic potential against fungal pathogens. Direct antagonistic and ISR effects of these isolates against fungal pathogens of tomato evidenced their possible use as a biocontrol agent.</p>