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 - S5b

FUNCTIONAL ANALYSIS OF THE MYB-LIKE TRANCRIPTION FACTOR-S IN ARABIDOPSIS

Galbiati M., Cominelli E., Conti L., Tonelli C.

Dipartimento di Genetica e Biologia dei Microrganismi, Via Celoria 26, 20133 Milano, Italy

transcription factors, MYB-like genes, Arabidopsis, trichomes, anthocyanin

In the attempt of elucidating the functional role of the MYB-LIKE Trancription Factor-S (TFM-S) we have analyzed the expression profile of the wild type allele in different plant tissues by RT-PCR and in-situ hybridization. Data indicate that TFM-S is expressed in the epidermal and sub-epidermal layers of leaves, sepals and carpels.

To further characterize the expression of TFM-S we have cloned a 900bp upstream region in front of the reporter gene GFP. Transgenic plant expressing the fusion construct exhibit a strong GFP expression in the guard cell of the stomata present in cotyledons, rosette leaves, stems, sepals and carpels.

Recently, we have identified, by a PCR-based screening approach, a null allele of TFM-S, in the Yale University T-DNA insertion lines. Plants homozygous for the insertion closely resemble the phenotype of ttg1 and ttg2 mutants . Mutant TFM-S individuals exhibit a glabrous phenotype in the rosette leaves, stems and sepals. Abnormal trichomes are exceptionally found only at the leaf margin. Moreover, mutant seeds lack the characteristic purple anthocyanin pigment in the endothelium layer and do not produce mucilage upon germination.

All together, these preliminary observations, suggest a role for the wild type TFM-S gene product in controlling different metabolic pathways confined to the epidermal and sub-epidermal layers of Arabidopsis organs.