Transcription factor activities calculated using NCA. (A) Predicted activities of the fifteen transcription factors used in this study. For each transcription factor, rows represent development stage. Activities of each row are normalized to the MP stage. (B) Transcription factor activities (red) compared to gene expression (blue), with Pearson correlation coefficients noted. Both activity and expression at each time point are normalized to the MP stage values, and the activity is further scaled for direct comparison with the expression values. (C) Correlation matrix between transcription factor activities. Red represents positive correlation, and blue represents negative correlation. (D) Inferred combinatorial regulation pairs of transcription factors. Red lines represent positive regulation, and blue lines represent negative regulation. Green square represents TFs associated with pollen development found by text-mining (The regulation of these TFs are putative).