Low diversity of T4-type bacteriophages in applied rice straw, plant residues and rice roots in Japanese rice soils: Estimation from major capsid gene (g23) composition


M. KIMURA, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan. Email: kimuram@agr.nagoya-u.ac.jp


The present study elucidated the diversity of T4-type bacteriophage communities in applied rice straw and plant residues in soil and rice roots by analyzing the composition of the major capsid gene (g23). The denaturing gradient gel electrophoresis (DGGE) band patterns of g23 fragments were simple and similar to each other without any seasonal change. Twenty-two, twenty and twenty-six g23 clones were obtained from applied rice straw, plant residues and rice roots, respectively. Most of the g23 clones belonged to Paddy Groups I, II, III, V and VIII for rice straw samples, to Paddy Groups I, II and V for plant residue samples, and to Paddy Groups I, II, III, V, VI and VIII for rice root samples, indicating a lower diversity of g23 genes at these sites than in bulk soils. No seasonal variation in the phylogenetic distribution of g23 clones was recorded, in contrast to clear seasonal variations in the bacterial communities at these sites.