Molecular analysis of the NAC gene family in rice

Genes that encode products containing a NAC domain, such as NO APICAL MERISTEM (NAM) in petunia, CUP-SHAPED COTYLEDON2 (CUC2) and NAP in Arabidopsis thaliana, have crucial functions in plant development. We describe here molecular aspects of the OsNAC genes that encode proteins with NAC domains in rice (Oryza sativa L.). Sequence analysis revealed that the NAC genes in plants can be divided into several subfamilies, such as the NAM, ATAF, and OsNAC3 subfamilies. In rice, OsNAC1 and OsNAC2 are classified in the NAM subfamily, which includes NAM and CUC2, while OsNAC5 and OsNAC6 fall into the ATAF subfamily. In addition to the members of these subfamilies, the rice genome contains the NAC genes OsNAC3, OsNAC4 (both in the OsNAC3 subfamily), OsNAC7, and OsNAC8. These results and Southern analysis indicate that the OsNAC genes constitute a large gene family in the rice genome. Each OsNAC gene is expressed in a specific pattern in different organs, suggesting that this family has diverse and important roles in rice development.