TABLE 1.

Primer combinations used in PCR

Combination no., taxon, and primer name	Primer sequence	Positions (E. coli numbering)	Source or reference	No. of different OTU types (taxon)a
				Fr	Mm	Uh
1
Universal				8 (Crenarchaeota)	23 (Crenarchaeota)
8f (fD2)	5′-AGAGTTTGATCATGGCTCA-3′	8-26	Modified from reference 39	7 (Bacteria)	2 (Bacteria)
1512r (rP2)	5′-CCGGCTACCTTGTTACGACTT-3′	1492-1512		7 (unidentified)	6 (unidentified)
Archaea
A109a	5′-ACKGCTCAGTAACACGT-3′	109-125	8
A934b	5′-GTGCTCCCCCGCCAATTCCCT-3′	915-934	35
2
Archaea				7 (Crenarchaeota)	7 (Crenarchaeota)	3 (unidentified)
Ar3f	5′-TTCCGGTTGATCCTGCCGGA-3′	7-26	12	2 (Bacteria)	2 (Euryarchaeota)
Ar9r	5′-CCCGCCAATTCCTTTAAGTTTC-3′	906-927	12
Archaea
A109a	5′-ACKGCTCAGTAACACGT-3′	109-125	8
A934b	5′-GTGCTCCCCCGCCAATTCCCT-3′	915-934	35
3
Archaea				4 (Crenarchaeota)
Ar3f	5′-TTCCGGTTGATCCTGCCGGA-3′	7-26	12	5 (unidentified)
A934b	5′-GTGCTCCCCCGCCAATTCCCT-3′	915-934	35
Archaea
A109a	5′-ACKGCTCAGTAACACGT-3′	109-125	8
Ar9r	5′-CCCGCCAATTCCTTTAAGTTTC-3′	906-927	12

^aFr, fine root; Mm, mycorrhiza; Uh, uncolonized humus.