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

Giardini Naxos, Italy - 18/21 September, 2002

ISBN 88-900622-3-1

Oral Communication Abstract - S5f

UBC10, A UBIQUITIN CONJUGASE INVOLVED IN STRESS-RELATED HORMONE SIGNAL TRANSDUCTION

FRUGIS G.*, PUANGSOMLEE P.**, MATHIAS ZEIDLER M.**, CHUA N.-H.**

*) Istituto di Biologia Agroambientale e Forestale (IBAF), CNR, Area della Ricerca di Roma, Via Salaria Km. 29,300, 00016 Monterotondo Scalo (Roma), Italia

**) Laboratory of Plant Molecular Biology, Rockefeller University, 1260 York Avenue, 10021 New York, NY, USA

ubiquitin conjugase, Arabidopsis thaliana, stress response, NACs

Ubiquitin-proteasome pathway (UPP) of protein degradation is an emerging theme in cell biology. Evidences for a key role in the control of many different cell functions such as cell cycle progression, endocytosis, protein sorting, regulation of transcription and receptors activity has been widely provided both in yeast and in animal field.

Ubiquitin is conjugated to target proteins through sequential reactions that involve activating (E1), conjugating (E2) and ligase (E3) enzymes.

We isolated a ubiquitin conjugase of Arabidopsis thaliana, UBC10, that interacted with members of the NAC family, in two-hybrid assays. NACs are transcription factors unique to plants that are involved in different aspects of plant development and hormone signal transduction.

In particular, the transcripts of the two NAC genes, that encode for the UBC10-interacting proteins, are modulated in response to wounding, methyl jasmonate (MeJa), abscisic acid (ABA) and ethylene. We found that UBC10 is expressed ubiquitously, downregulated in the dark and increased around two-fold in response to MeJa, ABA, SA and ethylene.

In order to investigate the role of UBC10 in the stress processes mediated by these hormones, a reverse genetics approach was used. Transgenic plants that overexpressed the UBC10 antisense or the UBC10 protein, either wild-type or mutated in the cystein required for ubiquitin-thiolester formation (dominant negative), were obtained.

Here we present the isolation of UBC10 and the characterization of transgenic plants that misexpress UBC10, with particular attention to stress-response and involvement in specific hormone signal transduction pathways.