This study focuses on the effects of long-term rice
rotated with milk vetch being as green manure on the composition
of bacteria in rice roots. The endophytic bacterial communities
in rice roots of the rice–rice–milk vetch (R-R-MV)
and the rice–rice–winter fallow (R-R-WF) crop rotations with
a 28-year research history were investigated using combined
culture-dependent and culture-independent methods. It was
found that the endophytic bacterial population in rice roots
with the green manure was significantly higher than that of
without it. There were 169 and 77 strains of endophytic
bacteria that were isolated from rice roots of the R-R-MV
and the R-R-WF, respectively. The 16S rRNA gene analysis
shows that the 77 R-R-WF bacteria belong to 15 species of 14
genera while the other 169 R-R-MV bacteria belong to 21
species of 19 genera, in which Herbaspirillum and Cedecea
were two mutually dominant populations and Burkholderia,
Pseudomonas , Sphingomonas, and Pantoea accounted for
large proportions of the endophytic bacteria in rice roots
through R-R-MV rotation. The analysis of 16S rDNA clone
libraries showed that the Shannon–Weaver diversity index of
endophytic bacteria in R-R-MVapproximates that in R-R-WF
rotation, whereas the richness indexes of Chao 1 and ACE in
R-R-MV rotation system were significantly higher than those
in R-R-WF rotation. The diversity of endophytic bacteria was
richer in R-R-MV. Both the culture-dependent and the cultureindependent
method revealed significant effect of long-term
different tillage systems on the microbial community.
This study focuses on the effects of long-term ricerotated with milk vetch being as green manure on the compositionof bacteria in rice roots. The endophytic bacterial communitiesin rice roots of the rice–rice–milk vetch (R-R-MV)and the rice–rice–winter fallow (R-R-WF) crop rotations witha 28-year research history were investigated using combinedculture-dependent and culture-independent methods. It wasfound that the endophytic bacterial population in rice rootswith the green manure was significantly higher than that ofwithout it. There were 169 and 77 strains of endophyticbacteria that were isolated from rice roots of the R-R-MVand the R-R-WF, respectively. The 16S rRNA gene analysisshows that the 77 R-R-WF bacteria belong to 15 species of 14genera while the other 169 R-R-MV bacteria belong to 21species of 19 genera, in which Herbaspirillum and Cedeceawere two mutually dominant populations and Burkholderia,Pseudomonas , Sphingomonas, and Pantoea accounted forlarge proportions of the endophytic bacteria in rice rootsthrough R-R-MV rotation. The analysis of 16S rDNA clonelibraries showed that the Shannon–Weaver diversity index ofendophytic bacteria in R-R-MVapproximates that in R-R-WFrotation, whereas the richness indexes of Chao 1 and ACE inR-R-MV rotation system were significantly higher than thosein R-R-WF rotation. The diversity of endophytic bacteria wasricher in R-R-MV. Both the culture-dependent and the cultureindependentmethod revealed significant effect of long-term
different tillage systems on the microbial community.
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