Studies on the colonization of Bacillus cereus C1L in theoots of Lilium formosanum
Date Issued
2008
Date
2008
Author(s)
Lin, Yu-Ju
Abstract
Gray mold disease, caused by Botrytis elliptica (Berk.) Cooke, is one of the most important fungal diseases in Lilium formosanum that causes severe losses of yield and quality of lilies. In general, field management by application of fungicides to prevent and decrease disease incidence frequently results in the evolvement of fungicide-resistant strains. Therefore, alternative control measures such as biological control are developed. A biocontrol strain of Bacillus cereus C1L had been screened from the rhizosphere of L. formosanum and it could suppress the disease severity of lily gray mold. In this study, fluorescent C1L strain was constructed by using a promoter driving the expression of chitinase CH of Bacillus cereus and a shuttle vector pHY300PLK to express green fluorescence protein (GFP) in both Escherichia coli and Bacillus cereus. The tests on the abilities of induced systemic resistance (ISR), inhibition of spore germination and hyphal growth, and the bacterial motility indicated that the GFP-labeled C1L strain was similar to the wild-type strain. Examination by confocal laser scanning microscopy showed the presence of GFP-labeled C1L bacterial cells inner the roots of L. formosanum seedlings. The C1L strain could adhere to the root hairs, enter the intercellular space of root surface layer, and present in the in-depth intercellular space of root tissues, indicating that this bacterium could be an epiphyte and endophyte in the plant roots. In order to identify the genes of B. cereus C1L involved in the root colonization, a transposon insertion mutant library including 340 mutant strains was constructed. These mutants were screened for motility and colonization ability within corn roots. The genes identified from mutants of losing colonization ability were predicted to encode nitric oxide dioxygenase cAMP-dependent protein kinase, N-acetylgalactosamine-6-phosphate deacetylase, glucose-specific IIABC component, replication protein…et al. The genes possibly involved in motility were predicted to encode DNA binding protein, hypothetical protein, and possible collagen-like protein integrase. A build-up of model for the colonization of strain C1L in the roots of L. formosanum is the future prospect.
Subjects
Bacillus cereus C1L
Lilium formosanum
biological control
colonization
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