Crenarchaeota colonize terrestrial plant roots

Microorganisms that colonize plant roots are recruited from, and in turn co ntribute substantially to, the vast and virtually uncharacterized phylogene tic diversity of soil microbiota. The diverse, but poorly understood, micro organisms that colonize plant roots mediate mineral transformations and nut rient cycles that are central to biosphere functioning. Here, we report the results of epifluorescence microscopy and culture-independent recovery of small subunit (SSU) ribosomal RNA (rRNA) gene sequences showing that member s of a previously reported clade of soil Crenarchaeota colonize both young and senescent plant roots at an unexpectedly high frequency, and are partic ularly abundant on the latter. Our results indicate that non-thermophilic m embers of the Archaea inhabit an important terrestrial niche on earth and d irect attention to the need for studies that will determine their possible roles in mediating root biology.