In vitro Screening and Molecular Genetic Markers Associated with Fungal Pathogenic Toxin Filtrate Tolerance in Potato

Potato is the fourth important food crop in the world and Egypt as well after rice, wheat and corn. Cultivated potatoes are tetraploid and highly heterozygous, making conventional breeding difficult, its vegetative propagation causing degeneration and accumulation of diseases. Callus induction and plant regeneration of some potato varieties (Cara, Diamont, King-Edward, Nicola and Hermes) were conducted. Stem segments, leaf disc and root tips explants were evaluated on the basis of their growth and ability on callus induction and regeneration media. The impacts of PGRs, cultivars and explant exporters on callus induction media were differ, and Nicola cultivar on CM4 (MS supplemented with 5 mg / L NAA + 1 mg/ L KIN) produced 100% callus induction with highest callus weight 750.5 mg using stem segments explant followed by Diamint 90% on CM4. The produced calli from stem segments occurred with high percentage 70 % for Diamont on RM1 (MS+ 2.25 mg/ L BA + 5 mg / L GA3). Steam segments of Diamont potato cultivars was used for callus induction and plantlets regeneration under culture toxin filtrate stress as in vitro selection of tolerance/resistance to F. oxysporum and A. solani toxin filtrate at 0, 5, 10, and 15 % on the callus induction on CM4 with the selection pressure and plant regeneration on RM1. No any plantlets preduced under selection with A. solani. In most cases, under selection of F. oxysporum increasing toxin filtrate in the tissue culture medium resulted in reduction in plantlet growth potential in erratic degrees, the highest percentage of regenerated calli and number of the obtained 15, 12 and 3 somaclones were obtained from the calli that were produced under 5, 10 and 15 % and no any stress on regeneration phase. However, using 10% toxin filtrate for produced calli under stress with 5, 10 and 15% of filtrate the regeneration decreased and were 5, 4 and 1 somaclones, respectively. RAPD and SRAP primers generated 48and 50 bands in total respectively with highly polymorphic patterns among original plant and its somaclones. The actual investigation signalized that the use of RAPD and SRAP – DNA markers were vigorous to disclose genetic diversity at the molecular grade between potato cultivars and their regenerates and somaclones besides, could be allows detecting changes due to in vitro selection to pathogens. This is the new in the process of genetic improvement to raise the resistance degree of potato for various diseases that threaten its final yield.