TOWARD THE FUNCTIONAL CHARACTERIZATION OF POTATO PARALLEL SPINDLES LIKE (PSL) GENES

In plants, whole-genome doubling largely contributed to plant evolution and diversification. Gametes with somatic chromosome number (2n) are now considered the major route of plant polyploidization. The parallel arrangement of the spindles (ps) in the 2nd division of male meiosis is the most common mechanism generating 2n pollen through the formation of dyads and triads. Arabidopsis thaliana Parallel Spindles1 (AtPS1) was recently reported as a major gene implicated in the control of the ps meiotic defect. In potato, we identified three Parallel Spindles Like loci (PSL1-3). To establish their role, two strategies were undertaken. Firstly, Arabidopsis mutant Atps1, kindly given by Dr. R. Mercier (INRA, Versailles), was transformed with the clone containing the genomic sequence corresponding to PSL3 from potato. Although PSL3 expression was detected in Atps1 transgenic line, the formation of dyads and triads persisted thereby indicating the absence of complementation. In the other strategy, PSLs RNAi silencing is being performed in diploid and tetraploid potato genotypes. Hairpin-RNAi expression vector containing a 400 bp sequence common to all PSLs was utilized for potato transformation by Agrobacterium tumefaciens. So far, twelve transgenic potato plants have been obtained. PSLs silencing is under evaluation and 2n pollen formation will be verified at the flowering stage.