EFFECT OF THE 3’ UTR ON THE PVLEA-18 GENE EXPRESSION IN RESPONSE TO WATER DEFICIT

BATTAGLIA M. AND COVARRUBIAS AA.

Barcelona, Junio 2003

Congreso; ISPMB (International Society. of Plant Molecular Biology); 2003

ISPMB (International Society. of Plant Molecular Biology)

We have previously shown that mRNA and protein encoded by the Pvlea-18 gene from Phaseolus vulgaris L., a member of a new family of Late Embryogenesis Abundant (LEA) proteins, accumulate in dark grown bean seedlings not only in response to water deficit but also during optimal irrigation (Plant Mol.Biiol. 35:393, 1997). We also have studied the Pvlea-18 gene transcriptional regulation by using transgenic Arabidopsis thaliana plants containing a chimeric gene consisting of the Pvlea-18 promoter region and the 3’-nos terminator fused to the GUS gene coding region. We demonstrated that the chimeric gene is active during Arabidopsis normal development under well-irrigated conditions, and that it is further induced in response to ABA and dehydration treatments. Replacing the 3’-nos terminator with the Pvlea-18 3’-region led to an additional increase in expression during development and in response to dehydration, but not in response to exogenous ABA. These results reveal an enhancer effect of the Pvlea-18 3’-region, which showed to be higher specifically under dehydration (Plant Mol.Biol. 45:501, 2001). Data using abi mutants as well as fluridone (an ABA biosynthesis inhibitor) indicate that the Pvlea-18 gene dehydration response is predominantly ABA-independent. In silico analysis of the Pvlea-18 3’ UTR region revealed conserved sequences between orthologous genes and between different water deficit responsive genes. We will present data that discern whether the Pvlea-18 3’ UTR region exerts a transcriptional or post-transcriptional regulation.