OsAP2-1, an AP2-like gene from Oryza sativa, is required for flower development and male fertility

Abstract

Arabidopsis AP2 (AtAP2) is a member of AP2 subfamily of the AP2/EREBP class of transcriptional factors and plays crucial roles in regulating floral meristem determinacy, floral organ identity and ovule and seed development. In order to examine functional conservation and diversification of AP2 genes in monocots, here we analyze a rice AtAP2-like gene, OsAP2-1. This gene was expressed at high levels in both flowers and roots, and at faint levels in buds or leaves. Its transcript was also present in mature pollen grains. The OsAP2-1 down-regulated lines mediated by RNA interference showed obvious alternation in floral organs of innermost two whorls, including the reduced stamens, fused anther filaments and increased number of pistils. Abortive seeds were observed in the down-regulated lines. These results suggest that OsAP2-1 is required for flower and seed development, consistent with the roles of AtAP2 in Arabidopsis. Furthermore, our results demonstrated that the down-regulation of the endogenous transcripts led to decreased pollen viability and germination activity, suggesting that OsAP2-1 has roles in controlling pollen development.