Romeuf et al. BMC Genomics 2010, 11:185 http://www.biomedcentral.com/1471-2164/11/185 Page 4 of 15 Figure 2 Categories of the 226 cDNA libraries used to identify wheat TFs. Spike origin refers to libraries from flower, spikelet, seed or entire spike tissue. belongs to a specific TF subfamily according to its degree of similarity to the respective subfamily member from rice. After this step 3,820 sequences were found to correspond to bona fide wheat TFs as they have the DNA-binding domain required to validate their status as transcriptional regulators. We chose to keep all sequences identified by their overall similarity with rice TF proteins in wDBTF and gave information on the positions of Pfam motifs on the table of subfamilies web page. Classification of wheat TF families The wheat sequences were assigned to TF families by taking into account the best BLAST hit against rice TF proteins classified in the DRTF database http://drtf.cbi. pku.edu.cn/. In the wheat data set we found members corresponding to every rice TF family suggesting that TF families are conserved between rice and wheat. In wDBTF, wheat TF members were distributed across 40 families and 84 subfamilies. The NAC subfamily is the largest with at least 269 members. Among the other