The TEIL (Tobacco EIN3-Like) gene is a tobacco homologue of arabidopsis Ethylene Insensitive 3 (EIN3), and the gene product binds an 8 bp sequence in the tobacco PR1a promoter in a sequence specific manner. It was found here that accumulation of TEIL transcript was induced by wounding and preceded basic PR gene expression. To study the downstream signalling pathway of TEIL, TEIL was overexpressed under the control of the constitutive 35S promoter in tobacco plants. In 35S::TEIL lines, basic PR genes, which are wound-, jasmonate-, and ethylene-inducible, were expressed constitutively. Next, the conserved 781 bp sequence among tobacco EIN3-like (EIL) protein genes was introduced as an inverted-repeat (IR) into tobacco to suppress expression of these genes. In two independent IRTEIL lines, the TEIL transcript was not found and transcripts of other tobacco EILs, NtEIL3, and NtEIL5, were reduced. In IRTEIL plants, wound-, jasmonate-, and ACC-induced accumulation of basic PR gene transcripts was significantly inhibited. These results indicate that TEIL functions upstream of tobacco basic PR genes in wound signalling via not only ethylene but also jasmonate. In 35S::TEIL plants, the pistil length of the flower was longer with a slight protrusion of the stigma compared with the control. In IRTEIL plants, the length of the stamens was shorter than the control with significant protrusion of the stigma in the flower. These observations indicate the involvement of tobacco EILs in flower development.

By random amplified polymorphic DNA (RAPD) analysis of the representative isolates of each race of Fusarium oxysporum f. sp. lactucae, RAPD fragments of 0.6, 1.6, and 2.9 kb were obtained. The 0.6-kb RAPD fragment was common to the representative isolates of all three races. Amplification of the 1.6-and 2.9-kb fragments were unique to the isolates of races 1 and 2, respectively. Sequence tagged site (STS) marker FLA0001, FLA0101, and FLA0201 were generated from the 0.6-, 1.6-, and 2.9-kb RAPD fragments, respectively. Polymerase chain reaction (PCR) analysis showed that FLA0001 was common to all 49 isolates of F. oxysporum f. sp. lactucae. FLA0101 was specifically generated from all 23 isolates of race 1 but not from races 2 or 3. FLA0201 was specifically amplified from all 12 isolates of race 2 but not from races 1 or 3. In two isolates of F. oxysporum f. sp. lactucum, PCR amplified FLA0001 and FLA0101 but not FLA0201. On the other hand, these STS markers were not detected from isolates of five other formae speciales. Because these STS markers were not generated from isolates of other plant pathogenic fungi, bacteria, or plant materials examined in this study, PCR analysis combined with the three STS markers should be a useful means for rapid identification of races of F. oxysporum f. sp. lactucae.

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.

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