Abstract
EL5 in rice encodes membrane-localized E3 ubiquitin ligase with a RING-H2 domain. We have demonstrated that nitrate causes necrosis in transgenic rice roots that overexpress EL5V162A with impaired E3 activity (mEL5-5). We report here that compared to non-transgenic rice plant (NT), elongation of crown roots in mEL5-5 was normal, but the number of lateral root increased when cultured in N-source-free medium. Cells around the lateral root emergence sites in mEL5-5 became necrotic when treated with nitrite. This treatment enhanced NO production, but its level and location in mEL5-5 and NT were the same. On the other hand, ROS was increased only in mEL5-5 treated with nitrite. The ROS production was at the same site where NO production and cell death occurred. These results suggest that EL5 is involved in the lateral root formation and cell death by controlling the ROS production downstream of NO signaling.
