Comparison of development stage-enriched (A) and pollen preferential genes (B) in rice and Arabidopsis. The large pie shows the numbers of rice development stage-enriched (A) or pollen-preferential genes (B) with or without homologs in the Arabidopsis genome. NH, no homologs; AG, having homologs. The small pie shows the numbers of the homologs in different expression patterns in Arabidopsis. PE, expression in pollen; PP, pollen-preferential expression; SE, pollen stage-enriched expression; others, undetectable expression in pollen. The transcriptome data of developing pollen of Arabidopsis were from . Detailed information is in Additional file 8.