Microarray analysis reveals similarities and variations in genetic programs controlling pollination/fertilization and stress responses in rice (Oryza sativa L.).

Previously, we identified 253 cDNAs that are regulated by pollination/fertilization in rice by using a 10K cDNA microarray. In addition, many of them also appeared to be involved in drought and wounding responses. To investigate this relationship, we obtained their expression profiles after dehydration and wounding treatments in this study. Venn diagram analysis indicated that 53.8% (136/253) and 21% (57/253) of the pollination/fertilization-related genes are indeed regulated by dehydration and wounding, respectively, and nearly half of the genes expressed preferentially in unpollinated pistils (UP) are responsive to dehydration. These results indicated that an extensive gene set is shared among these responses, suggesting that the genetic programs regulating them are likely related. Among them, the genetic network of water stress control may be a key player in pollination and fertilization. Additionally, 39.5% (100/253) cDNAs that are related to pollination/fertilization appear not to be regulated by the stress treatments (dehydration and wounding), suggesting that the existence of additional genetic networks are involved in pollination/fertilization. Furthermore, comparative analysis of the expression profiles of the 253 cDNAs under 18 different conditions (various tissues, treatments and developmental status) revealed that the genetic networks regulating photosynthesis, starch metabolisms, GA- and defense-responses are involved in pollination and fertilization. Taken together, these results provided some clues to elucidate the molecular mechanisms of pollination and fertilization in rice.