title: Distinctive bacterial communities in the rhizoplane of four tropical tree species.
abstract: It is known that the microbial community of the rhizosphere is not only influenced by factors such as root exudates, phenology, and nutrient uptake but also by the plant species. However, studies of bacterial communities associated with tropical rainforest tree root surfaces, or rhizoplane, are lacking. Here, we analyzed the bacterial community of root surfaces of four species of native trees, Agathis borneensis, Dipterocarpus kerrii, Dyera costulata, and Gnetum gnemon, and nearby bulk soils, in a rainforest arboretum in Malaysia, using 454 pyrosequencing of the 16S rRNA gene. The rhizoplane bacterial communities for each of the four tree species sampled clustered separately from one another on an ordination, suggesting that these assemblages are linked to chemical and biological characteristics of the host or possibly to the mycorrhizal fungi present. Bacterial communities of the rhizoplane had various similarities to surrounding bulk soils. Acidobacteria, Alphaproteobacteria, and Betaproteobacteria were dominant in rhizoplane communities and in bulk soils from the same depth (0-10 cm). In contrast, the relative abundance of certain bacterial lineages on the rhizoplane was different from that in bulk soils: Bacteroidetes and Betaproteobacteria, which are known as copiotrophs, were much more abundant in the rhizoplane in comparison to bulk soil. At the genus level, Burkholderia, Acidobacterium, Dyella, and Edaphobacter were more abundant in the rhizoplane. Burkholderia, which are known as both pathogens and mutualists of plants, were especially abundant on the rhizoplane of all tree species sampled. The Burkholderia species present included known mutualists of tropical crops and also known N fixers. The host-specific character of tropical tree rhizoplane bacterial communities may have implications for understanding nutrient cycling, recruitment, and structuring of tree species diversity in tropical forests. Such understanding may prove to be useful in both tropical forestry and conservation.
authors: School of Biological Sciences, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-747, Republic of Korea.
authors: Yoon Myung
authors: YM
authors: Oh
authors: Mincheol
authors: M
authors: Kim
authors: Larisa
authors: L
authors: Lee-Cruz
authors: Ang
authors: A
authors: Lai-Hoe
authors: Rusea
authors: R
authors: Go
authors: N
authors: N
authors: Ainuddin
authors: Raha Abdul
authors: RA
authors: Rahim
authors: Noraini
authors: N
authors: Shukor
authors: Jonathan M
authors: JM
authors: Adams
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D041963:Bacteroidetes / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D020562:Betaproteobacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D017753:Ecosystem; D020459:Genes, rRNA; D008296:Malaysia; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D058441:Rhizosphere; D017422:Sequence Analysis, DNA / Q000379:methods; D013045:Species Specificity; D057949:Streptophyta / Q000254:growth & development / Q000382:microbiology*; D064028:Tracheophyta / Q000254:growth & development / Q000382:microbiology*; D014197:Trees / Q000382:microbiology; D014329:Tropical Climate
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S