Involvement of two rice ETHYLENE INSENSITIVE3-LIKE genes in wound signaling

Ethylene and jasmonic acid (JA) have been proposed as key compounds for wound signaling in plants. In Arabidopsis, ETHYLENE INSENSITIVE3 (EIN3), which is an essential transcription factor for ethylene signaling, is regulated at the post-transcriptional level, while transcriptional regulation of EIN3 or EIN3-LIKE (EIL) genes has not been well documented. The expression of 6 rice EIL genes (OsEIL1-6) was analyzed and only OsEIL1 and 2 were found to be wound-inducible EIL. OsEIL2 was also induced by JA. Electrophoretic mobility shift assays showed that recombinant OsEIL1 and 2 proteins bound to specific DNA sequences that are recognized by a wound-inducible tobacco EIL. Accumulation of OsEIL1 and 2 transcripts reached a maximum at 1 and 0.5 h after wounding, respectively, and the corresponding DNA-binding activity in nuclear extracts of rice leaves was increased at 1 h after wounding. Candidates for OsEIL-target genes were selected by microarray analysis of wounded rice and by promoter sequence analyses of wound-inducible genes identified by microarray analysis. In OsEIL1- and/or 2-suppressed rice plants, the expression of at least four of 18 candidate genes analyzed was down-regulated. These results indicate the importance of inducible OsEILs in wound signaling in rice.