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

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

ANALYSIS OF THE GST GENES CLUSTERS IN ARABIDOPSIS

SANTELIA D., SORANZO N., MIZZI L, PÈ M.E.

Dipartimento di Genetica e di Biologia dei Microrganismi, Università di Milano

Among the many enzyme systems involved in the detoxification of toxic compounds, the family of glutathione S-transferases (GSTs) represents a particularly appealing study system due to its ubiquitous expression and broad substrate specificity. Glutathione-S-transferases catalyse the addition of glutathione to toxic electrophilic compounds to form inactive conjugates. The GST activity is induced in response to various stresses, including pathogen attack, chemical stress due to xenobiotic compounds and oxidative stress caused by heavy metals. Aim of this study is the characterization of the multigenic GST family, in term of number of members and their belonging to the different GST classes, in the model species Arabidopsis thaliana, in order to elucidate the relationship between genomics and proteomics of GSTs. By means of a screening in the NCBI Data Base, 47 different putative GST-encoding sequences were identified. The analysis of their relative position in the genome, performed by alignment programs (BioEdit, Clustal and Local Blast), revealed the existence of a GST organization on the chromosome in repeated units, in form of clusters. This suggests that the evolution of this family occurred through a series of subsequent duplications. This was confirmed by a comparative analysis of homology between various genes; it showed that sequences arranged in tandem have a higher degree of similarity than sequences belonging to different clusters. In general, the nearness of the genes on the chromosome is associated with a greater level of similarity, indicating the existence of a common progenitor, which subsequently extended by duplications. On the basis of these results, further analyses have been performed on specific regions of the sequences, which are correlated with their expression profile (promoters, UTRs, coding sequences and introns). The study was carried out by a bioinformatics approach, using programs such as Gene scan, Gene finder and others. We intend to validate this interpretative model by experimental analyses on expression profiles of genes of interest.