Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Oral Communication - S1c

TRANSCRIPTIONAL ACTIVATION OF RETROTRANSPOSONS INDUCES DESICCATION TOLERANCE IN CALLUS TISSUE OF CRATEROSTIGMA PLANTAGINEUM

A. FURINI, L. BORGATO, S. VAROTTO, F. SALAMINI, D. BARTELS

Dip. Scientifico e Tecnologico, Università degli Studi di Verona, Strada Le Grazie 15, 37134 Verona

Drought tolerance in the resurrection plant Craterostigma plantagineum is restricted to fully developed plants. In callus this phenomenon can be induced by treatment with abscisic acid.

Based on T-DNA activation tagging, an element (CDT-1) was isolated whose induced transcription resulted in the formation of a desiccation-tolerant callus in the absence of exogenously applied abscisic acid. Craterostigma genes normally induced by desiccation are constitutively induced in the transgenic callus. Hybridization analysis with the cDNA probe revealed that the CDT-1 is a member of a gene family; the analysis of cDNA and genomic clones indicates that the isolated element do not resemble canonical members of so far known plant signalling pathways, since it codes for unusual primary transcript with no large ORFs for proteins. Transcribed regions of the CDT-1 are flanked by short direct sequence repeats. A sequence alignment of these direct repeats shows that they are of different lengths, but carry common core sequences. This feature of repeats suggests a close analogy to sequence duplications flanking the integration target sites of eukaryotic retrotransposons.

Further experiments demonstrated that the polyadenylated transcripts of CDT-1 act as regulatory RNAs and the transcripts are present only in particular cell types of Craterostigma tissue.