S K Verma1,2, J F White1. 1. Department of Plant Biology, Rutgers University, New Brunswick, NJ, USA. 2. Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi, Uttar Pradesh, India.
Abstract
AIMS: This study was conducted to investigate indigenous seed endophyte effects on browntop millet seedling development. We report that seed-inhabiting bacterial endophytes are responsible for promoting seedling development, including stimulation of root hair formation, increasing root and shoot length growth and increasing photosynthetic pigment content of seedlings. Bacterial endophytes also improved resistance of seedlings to disease. METHODS AND RESULTS: A total of four endophytic bacteria were isolated from surface-sterilized seeds and identified by 16S rDNA sequencing as Curtobacterium sp. (M1), Microbacterium sp. (M2), Methylobacterium sp. (M3) and Bacillus amyloliquefaciens (M4). Removal of bacteria with streptomycin treatment from the seeds compromised seedling growth and development. When endophytes were reinoculated onto seeds, seedlings recovered normal development. Strains M3 and M4 were found to be most potent in promoting growth of seedlings. Bacteria were found to produce auxin, solubilize phosphate and inhibit fungal pathogens. Significant protection of seedlings from Fusarium infection was found using strain M4 in microcosm assays. The antifungal lipopeptide genes for surfactin and iturin were detected in M4; culture extracts of M4 showed a positive drop collapse result for surfactins. CONCLUSIONS: This study demonstrates that browntop millet seeds vector indigenous endophytes that are responsible for modulation of seedling development and protection of seedlings from fungal disease. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is significant and original in that it is the first report of seed-inhabiting endophytes of browntop millet that influence seedling development and function in defence against soilborne pathogens. This study suggests that conservation and management of seed-vectored endophytes may be important in development of more sustainable agricultural practices.
AIMS: This study was conducted to investigate indigenous seed endophyte effects on browntopmillet seedling development. We report that seed-inhabiting bacterial endophytes are responsible for promoting seedling development, including stimulation of root hair formation, increasing root and shoot length growth and increasing photosynthetic pigment content of seedlings. Bacterial endophytes also improved resistance of seedlings to disease. METHODS AND RESULTS: A total of four endophytic bacteria were isolated from surface-sterilized seeds and identified by 16S rDNA sequencing as Curtobacterium sp. (M1), Microbacterium sp. (M2), Methylobacterium sp. (M3) and Bacillus amyloliquefaciens (M4). Removal of bacteria with streptomycin treatment from the seeds compromised seedling growth and development. When endophytes were reinoculated onto seeds, seedlings recovered normal development. Strains M3 and M4 were found to be most potent in promoting growth of seedlings. Bacteria were found to produce auxin, solubilize phosphate and inhibit fungal pathogens. Significant protection of seedlings from Fusarium infection was found using strain M4 in microcosm assays. The antifungal lipopeptide genes for surfactin and iturin were detected in M4; culture extracts of M4 showed a positive drop collapse result for surfactins. CONCLUSIONS: This study demonstrates that browntopmillet seeds vector indigenous endophytes that are responsible for modulation of seedling development and protection of seedlings from fungal disease. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is significant and original in that it is the first report of seed-inhabiting endophytes of browntopmillet that influence seedling development and function in defence against soilborne pathogens. This study suggests that conservation and management of seed-vectored endophytes may be important in development of more sustainable agricultural practices.
Authors: April Micci; Qiuwei Zhang; Xiaoqian Chang; Kathryn Kingsley; Linsey Park; Peerapol Chiaranunt; Raquele Strickland; Fernando Velazquez; Sean Lindert; Matthew Elmore; Philip L Vines; Sharron Crane; Ivelisse Irizarry; Kurt P Kowalski; David Johnston-Monje; James F White Journal: Biology (Basel) Date: 2022-06-07
Authors: James F White; Kathryn L Kingsley; Qiuwei Zhang; Rajan Verma; Nkolika Obi; Sofia Dvinskikh; Matthew T Elmore; Satish K Verma; Surendra K Gond; Kurt P Kowalski Journal: Pest Manag Sci Date: 2019-07-27 Impact factor: 4.845
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