Microbes and Environments
Online ISSN : 1347-4405
Print ISSN : 1342-6311
ISSN-L : 1342-6311
Regular Paper
Culturable Endophytic Bacterial Flora of the Maturing Leaves and Roots of Rice Plants (Oryza sativa) Cultivated in a Paddy Field
Hironobu ManoFumiko TanakaChizuru NakamuraHiroko KagaHisao Morisaki
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JOURNAL FREE ACCESS

2007 Volume 22 Issue 2 Pages 175-185

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Abstract

The culturable endophytic bacteria in the leaves and roots of rice plants (Oryza sativa, cultivar Kinuhikari) cultivated on an experimental plot adjacent to a paddy field were studied during the maturation process, and a comparison with the bacteria inside rice seeds reported in a previous study was conducted. Culturable epiphytic bacteria were also isolated from the leaves and compared with the endophytic bacteria. The isolates were identified based on their 16S rRNA gene sequences. Many endophytes closely related to Bacillus, Curtobacterium, Methylobacterium, Sphingomonas and Pantoea from the leaves, and to Bacillus, Brevibacillus, Mycobacterium, Enterobacter, and Chryseobacterium from the roots were isolated. The endophytic bacterial flora of the leaves was similar to that of the seeds, but differed from that of the roots. As the rice plant matured, the ratio of Gram-negative strains among the isolates increased in the leaves (the isolates related to Curtobacterium decreased in number and those related to Methylobacterium and Pantoea increased), whereas the ratio of Gram-negative strains decreased in the roots (the isolates related to the order Rhizobiales decreased in number and were replaced by strains related to Bacillus and Brevibacillus capable of forming endospores). The isolates from the inside and surface of the leaf were closely related to 13 and 19 species, respectively. Among these isolates, the following 6 species related to Bacillus pumilus, Curtobacterium citreum (or C. flaccumfaciens, C. pusillum as the closest species), Methylobacterium aquaticum, Methylobacterium fujisawaense (or M. radiotolerans), Sphingomonas melonis and Sphingomonas yabuuchiae were common to both sites and constituted the majority at both sites.

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© Japanese Society of Microbial Ecology / Japanese Society of Soil Microbiology / Taiwan Society of Microbial Ecology
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