Submitted to: Cellular and Molecular Aspects of Ethylene Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: December 10, 2002
Publication Date: March 10, 2003
Citation: Tucker, M.L., Whitelaw, C.A., Lyssenko, N.N., and Mattoo, A.K. 2003. Reduced expression of the LeETR1 transcript in tomato results in delayed abscission, shorter internodes and reduced auxin movement. In: M. Vendrell, H. Klee, J.C. Pech and F. Romojaro, editors. Biology and Biotechnology of the Plant Hormone Ethylene III. Amsterdam: IOS Press. p. 21-26.
Stable transformation of tomato plants with a construct containing the antisense sequence for the receiver domain and 3' untranslated portion of the tomato ethylene-receptor LeETR1 under the control of an enhanced CaMV 35S promoter resulted in delayed abscission, shorter internodes and reduced auxin movement. Fruit coloration and softening were essentially unaffected, and all the seedlings displayed a normal triple response to ethylene. The delayed abscission phenotype is the opposite of that expected for the down regulation of an ethylene receptor. We propose that the delayed abscission phenotype is caused by an indirect affect on auxin movement that causes a higher than normal concentration of auxin in the abscission zone. In addition, site-directed mutagenesis was used to identify both positive and negative cis-acting elements that control auxin and ethylene regulation of the bean abscission cellulase (BAC) promoter. Auxin appears to regulate BAC gene expression at cis-acting elements that are independent of an ethylene and abscission-specific element. An 18 bp ethylene-dependent BAC element (Z-BAC) fused to a minimal -50 35S CaMV promoter displayed a 13-fold enhancement in abscission-specific expression over that of the minimal promoter alone. A yeast one-hybrid screen of an AZ cDNA library was used to identify candidate transcription factors that may be involved the regulation of abscission-specific gene expression.