Expression profiles of regulatory genes throughout male gametophyte development. (a) Core cell-cycle genes; (b) transcription factors; (c-f) selected transcription factor families. (c) R2R3-MYB; (d) WRKY; (e) NAC; (f) C3H. Expression profiles of all transcription factor families analyzed are available as Additional data files 1 and 3. (g) Core translation factors. (h) Poly(A)-binding (PAB) protein genes. Putative male gametophyte-specific (bold) or enhanced (bold dashed) genes are highlighted.