Figure 4.

The sequential action of mutually interacting transcription factors directs transcriptome dynamics during pollen maturation. AtMIKC* complexes repress immature pollen specific transcription factors such as WRKY34, and activate mature pollen specific transcription factors such as AGL18 and AGL29. These in turn predominantly repress transcripts that peak in immature tricellular pollen (TCP). In addition, AtMIKC* complexes also repress AGL30 and AGL65 in a negative feedback loop, whereas AGL18 acts to fine tune the expression level of AGL29. For most genes displayed in this scheme, we confirmed the differential expression in wild-type and triple mutant pollen by reverse transcription polymerase chain reaction (Additional data file 5). In this scheme only MYB97 and WRKY34 are potential direct targets of the AtMIKC* complexes, as suggested by in silico analysis of their putative regulatory sequences (Additional data file 2). BCP, bicellular pollen; MPG, mature pollen grains; UNM, unicellular microspores.