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The cultivated potato S. tuberosum is an autotetraploid (2n=4x=48) with basic chromosome number x=12, and a haploid genome size of approximately 840 Mbp. Thanks to the following specific biological and genetic features its ploidy can be easily manipulated: 1) several genotypes produce 2n gametes; 2) the EBN (Endosperm Balance Number) model can be used as a predictor of crossability between parents and ploidy level of the offspring; 3) maternal haploids can be quickly extracted following crosses with pollinator clones of S. phureja and 4) in vitro tissue culture techniques can be easily applied.

For practical breeding pourposes, our laboratory is working on the production of polyploids from diploid species. Indeed, polyploidization may allow to overcome crossing barriers. Polyploid plants are often produced sexually through the functioning of 2n gametes. The hybridization scheme used is the one based on the so called analytic breeding (4x - 2x crosses) involving S. tuberosum and haploid-species hybrids. Alternatively, bridge ploidies areused. Polyploids are also produced somatically, through protoplast electrofusion or colchicine/oryzaline treatments.

Our group is also involved in a wide multidisciplinary program aimed at understanding the events underlying early polyploid formation. We have autotetraploids of diploid potato species (e.g. S. commersonii, S. bulbocastanum) and have produced a Combimatrix CustomArray 90K microarray chip for transcriptomic analysis. Our studies are focused on several aspects, including:

1. genetics,

2. epigenetics,

3. transcriptomics,

4. metabolomics and

5. morpho-anatomy.

As a whole, we believe that these activities will allow us to study the plasticity of plant genomes and to interpret molecular changes associated to polyploidy. The molecular and cytological analysis on diploid, triploid, pentaploid and aneuploid genotypes brought us up several unanswered questions we wish to reply with innovative genomic approaches.