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 - 1.05

EXPRESSION PATTERN AND CELLULAR LOCALISATION OF ZEA MAYS RPD3-TYPE HISTONE DEACETYLASES DURING PLANT DEVELOPMENT

S. VAROTTO*, S. LOCATELLI**, S. CANOVA*, A. PIPAL***, M. MOTTO**, V. ROSSI**

*) Dipartimento di Agronomia Ambientale e Produzioni Vegetali, Università di Padova, viale dell’Università 16, I-35020 Legnaro (PD), Italy

**) Istituto Sperimentale per la Cerealicoltura, Sezione di Bergamo, via Stezzano 24, I-24126 Bergamo, Italy

***) Department of Molecular Biology, University of Innsbruck, Medical School, A-6020 Innsbruck, Austria

chromatin, expression pattern, HDACs, histone modifications, protein interaction

In chromatin, eukaryotic DNA is tightly wrapped around octamers of histones proteins, restricting its accessibility to factors involved in DNA replication and transcription. Local or extended structural chromatin changes play an important role in the control of gene expression and are controlled by complexes that remodel chromatin and by enzymes that posttranslationally modify histones (Verdin et al. 2003 Trends Genet 19: 286-293). Histone acetylation is the best-characterized type of histone modifications (Wu and Grunstein 2000 Trends Biochem Sci 25: 619-623). The enzymes responsible for maintaining the steady-state balance of histone acetylation are the histone acetyltransferases (HATs) and histone deacetylases (HDACs). Many of the recently identified HATs and HDACs have been found to be transcriptional co-activators and co-repressors, thus establishing a direct link between histone acetylation and regulation of gene transcription.

Different HDAC genes have been identified in plants and their classification into three distinct gene families has been proposed by The Plant Chromatin Initiative (http://chromdb.biosci.arizona.edu). The first family, the HDA gene family, is the Rpd3/Hda1 super-family, which contains members related to the yeast sequences Rpd3. The expression pattern and cellular localization of the maize Rpd3-type histone deacetylases ZmRpd3/101, ZmRpd3/102, and ZmRpd3/108 showed that their transcripts are expressed in all the organs and cellular domains analyzed but that their amount changed during development. A similar expression pattern and a nucleus/cytoplasmic localization was observed for ZmRpd3 proteins. GST pull-down assays showed that ZmRpd3 proteins can interact with the maize retinoblastoma-related (ZmRBR1) and retinoblastoma-associated (ZmRbAp1) proteins and that the three ZmRpd3s did not compete with each other in the binding. These results indicate a global role of ZmRpd3 genes in plant cell cycle and development, probably by affecting several metabolic pathways and suggest mechanisms regulating their transcription and protein accumulation. The important role played by HDAC in maize development is also emerging from the characterisation of antisense and over-expressing mutants that is in progress in our labs.