Isolation and characterization of endophytic bacteria from rice root cultivated in Korea = 한반도 중부지방의 벼 뿌리로부터 내생 세균의 분리와 특성 분석

Abstract

The 44 endophytic bacterial strains were isolated from surface-sterilized root of rice cultivated in seven different locations of Chungcheong province, Korea. Each isolate was introduced into rice seedlings grown gnotobiotically by inoculating scissor-cut first true leaf with cell suspensions, and the colonization capacity of each isolate in root tissue was analyzed at 7 days after inoculation. Sixteen out of 44 isolates were re-isolated from root successfully with the frequency of 103-5 CFU/g tissue. Interestingly, seven out of 16 isolates were identified as Burkholderia species. The identity between inoculated strains and re-isolates was confirmed by genomic fingerprinting and 16S rDNA sequence analysis. By a confocal laser scanning microscopic observation it was revealed that KJ001 strain, one of the sixteen isolates tagged with gfp colonized in root tissue especially around xylem. Six out of seven Burkholderia strains obtained in this study showed antagonizing activities against seven different fungal pathogens, contain niJH gene, and five of them enhanced growth of cucumber over 30%. The isolates showed no hypersensitive response on tobacco leaves and no pathogenecity in rice. From these results it was found that the endophytic Burkholderia strains will be useful in agriculture to develop a biocontrol agent or a bio-fertilizer.