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

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 1.09

CHARACTERIZATION OF THE WRKY GENE FAMILY IN ORYZA SATIVA

S. BERRI, M. KATER, E. PÈ

Department of Biomolecuar Science and Biotechnology, University of Milan

WRKY, expression profiling, abiotic stress

WRKY genes encode a family of transcription factors unique to plants characterized by the presence of one or two WRKYGQK motifs within a wider 60 aa consensus domain. Very little is known about this gene family, although some studies (mainly in Arabidopsis thaliana) showed their involvement in a variety of processes like the response to biotic and abiotic stresses, trichome development, senescence and biosynthesis of secondary metabolites. Recently, expression profiling of all 72 Arabidopsis WRKY genes demonstrated that many members of this family are actually transcriptionally regulated by pathogen infection and salicylic acid treatment. (Jixin et al., 2003).

Annotation of the rice genome sequence (which is still incomplete) resulted in the identification of 53 WRKY genes. The total predicted number is around 80 genes.

With the aim to characterise this gene family in rice, we compared the protein sequences of the 53 WRKY genes and produced a tree using the C-terminal consensus sequence. By including also the Arabidopsis sequences, we showed that similarity among homologous genes of different species is higher than among genes of the same species. Furthermore, this analysis showed that the Arabidopsis classification of WRKY genes (Eulgem et al., 2000) can be applied to rice genes as well.

To study the expression of the rice WRKY genes with regards to their expression pattern under oxidative stresses (H₂O₂), temperature stresses (cold) or salicylic acid induction, gene specific probes were spotted on filters and hybridised with cDNA probes derived from RNA extracted from the stressed plants.

For the functional analysis of WRKY genes we are analysing insertion (knockout) mutants. Four Tos17 mutants were identified in the rice insertion mutant database (http://tos.nias.affrc.go.jp/~miyao/pub/tos17/index.html.en). The analysis of these lines is in progress.