Figure 1.

Phylogenetic tree of B-type RR family members. The full-length protein sequences of poplar B-type RRs deduced from cDNA sequences (EMBL: FN908138 to FN908145) were aligned using Muscle [41] with those of Arabidopsis (ARRs), soybean (GmRRs), maize (ZmRRs) and rice (OsRRs), obtained from respective genome databases (Additional file 2). Maximum likelihood tree reconstructions were performed with MEGA 5 [42] using the JTT substitution model [43]. The C-type ARR22 from Arabidopsis was used as outgroup. Numbers indicate bootstrap support (1000 replicates).