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

Giardini Naxos, Italy - 18/21 September, 2002

ISBN 88-900622-3-1

Poster Abstract - 5.06

MONITORING THE EXPRESSION PATTERN INDUCED BY THE OSMYB4 OVEREXPRESSION BY USING ARABIDOPSIS THALIANA MICROARRAY ANALYSIS

mizzi L.*, Bracale M.**, Vannini C.**, Locatelli F.***, Magnani E.***, Coraggio I.***

*) Dipartimento di Genetica e di Biologia dei Microorganismi, Università dell’Insubria, Via J.H. Dunant 3, 21100 Varese, Italy

**) Dipartimento di Biologia Strutturale e Funzionale, Università degli Studi di Milano, Via Caloria 26, 20133 Milano, Italy

***) Istituto Biologia e Biotecnologia Agraria, CNR, Via E. Bassini 15, 20133 Milano, Italy

microarray, cold tolerance, Myb transcriptional factor, Oryza sativa, transgenic plants

Osmyb4 is a rice gene, encoding for a myb transcriptional factor involved in cold acclimation. The Osmyb4 expression, detected at low level in rice coleoptiles grown for three days at 29°C, is strongly induced by treatments at 4°C. Its expression is induced in rice seedlings subjected to sub-lethal temperatures (10 and 15 °C) and not by other stresses or ABA treatment. We previously demonstrated the Myb4 transcriptional activity in transient expression on several cold-induced promoters (PAL2, ScD9 SAD and COR15a ). We also investigated the Osmyb4 function in vivo over-expressing its cDNA in Arabidopsis thaliana plants under the control of the constitutive CaMV35S promoter. The Myb4 over-expressing plants showed a significant increased cold and freezing tolerance, both as membrane and PSII stability and as whole plant tolerance. Myb4 is the first Myb factor involved in cold acclimation characterized up to now and therefore, there is not any information in literature on the pathway regulated by this transcriptional factor. In this study, we applied the microarray analysis, using 15000 ESTs of A. thaliana , to identify Myb4-regulated genes. Fluorescently labelled cDNAs were prepared from mRNAs isolated from wild-type and Osmyb4 transgenic plants. In total, almost 800 Myb4-inducible and 500 Myb4-repressed genes were identified by this analysis. In particular, it is of particular interest the induction of genes involved in: signal transduction (as transcriptional factors, kinases and phosphatases), stress and pathogen response (as PAL2, b-xylosidase, etc.), lipid and amino acid metabolism (as lipase, lipid transporter and asparagines synthase), translation machinery (as IF2, and ribosomal proteins). The exaustive analysis of microarray data will permit to identify the role of Myb4 in the cold induced pathway also in relation to already described pathway branches (such as CBF and SCOF1 regulated ones).