Characterization of leaf blade- and leaf sheath-associated bacterial communities and assessment of their responses to environmental changes in CO₂, temperature, and nitrogen levels under field conditions.
Rice shoot-associated bacterial communities at the panicle initiation stage were characterized and their responses to elevated surface water-soil temperature (ET), low nitrogen (LN), and free-air CO2 enrichment (FACE) were assessed by clone library analyses of the 16S rRNA gene. Principal coordinate analyses combining all sequence data for leaf blade- and leaf sheath-associated bacteria revealed that each bacterial community had a distinct structure, as supported by PC1 (61.5%), that was mainly attributed to the high abundance of Planctomycetes in leaf sheaths. Our results also indicated that the community structures of leaf blade-associated bacteria were more sensitive than those of leaf sheath-associated bacteria to the environmental factors examined. Among these environmental factors, LN strongly affected the community structures of leaf blade-associated bacteria by increasing the relative abundance of Bacilli. The most significant effect of FACE was also observed on leaf blade-associated bacteria under the LN condition, which was explained by decreases and increases in Agrobacterium and Pantoea, respectively. The community structures of leaf blade-associated bacteria under the combination of FACE and ET were more similar to those of the control than to those under ET or FACE. Thus, the combined effects of environmental factors need to be considered in order to realistically assess the effects of environmental changes on microbial community structures.
Memuro Research Station, Hokkaido Agricultural Research Center, National Agriculture and Food Research Organization.
Seishi
S
Ikeda
Takeshi
T
Tokida
Hirofumi
H
Nakamura
Hidemitsu
H
Sakai
Yasuhiro
Y
Usui
Takashi
T
Okubo
Kanako
K
Tago
Kentaro
K
Hayashi
Yasuyo
Y
Sekiyama
Hiroshi
H
Ono
Satoru
S
Tomita
Masahito
M
Hayatsu
Toshihiro
T
Hasegawa
Kiwamu
K
Minamisawa
D001419:Bacteria / Q000145:classification* / Q000235:genetics; D058448:Biota / Q000187:drug effects* / Q000528:radiation effects*; D002245:Carbon Dioxide / Q000032:analysis*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000032:analysis*; D012275:Oryza / Q000382:microbiology*; D010802:Phylogeny; D018515:Plant Leaves / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013696:Temperature
D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D002245:Carbon Dioxide; D009584:Nitrogen