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

MOLECULAR INVESTIGATION OF THE PETUNIA HYBRIDA MEI2 MEIOTIC GENE

MORETTI C.*, REALE L.*, LANFALONI L.**, FERRANTI F.*

* Dipartimento Biologia Vegetale Biotecnologie Agroambientali, Università degli Studi di Perugia

** Dipartimento Biologia Cellulare e Molecolare, Università degli Studi di Perugia

meiosis, fission yeast, Petunia hybrida

Nearly all eukaryotic organisms have the capacity to undergo meiosis. In the fission yeast, Schizosaccharomyces pombe, exit from the mitotic cycle and entry into meiosis is regulated by both nutritional signals and cell type (Yamamoto, 1996; Egel, 1989). Nutritional deprivation induces expression of mei3⁺ in diploid cells heterozygous for the mating type, and Mei3 protein inhibits the activity of Pat1 kinase. The mei2 gene is essential for meiosis (Egel, 1989). The null mutation in mei2 suppress pat1-driven haploid meiosis, suggesting that Mei2 may act downstream of Pat1 kinase (Watanabe et al., 1997). Mei2 is an RNA-binding protein carrying three potential RNA-recognition motifs. It is required for both premeiotic DNA synthesis and the first meiotic division, and co-operates with a unique polyadenylated RNA molecule called meiRNA to promote this division (Watanabe and Yamamoto, 1994).

By combining a PCR based approach and cDNA library screening we cloned the complete cDNA of a Petunia hybrida Mei2 homologue which was called Pethy;Mei2.

Southern analysis showed that more then one copy of Pethy;Mei2 for haploid genome are present. The genomic sequence was also cloned and sequenced. It is 3928bp in length and presents 11 exons and 10 introns.

Expression studies indicated that Pethy;Mei2 mRNA is present in all floral organs, in leaves and roots; the expression level, however, differed between floral organs being the highest in ovaries and the weakest in sepals.

In situ hybridisation, using the complete antisense Pethy;Mei2 mRNA probes, was carried out to disclose its spatial localisation within ovaries.

Pethy;Mei2 mRNA was mainly localised in ovules in particular in the ovule integument and around both the megaspore mother cell (MMC) and the embryosac.