Cytogenetic Analysis of Some Susceptible and Resistant Potato Cultivars to Early Blight Disease

Potato is one of the important and strategic crops, which limiting factors such as diseases reduce its yield. The cytological studies of some of resistant and susceptible cultivars of potato to early blight disease, Alternarias spp. that is A. alternata and A. solani which are important in potato fields were considered. The cultivars were including: ‘Agria’, ‘Santé’, ‘Shepody’, ‘Milova’, ‘Boren’ and ‘Ramose’. Measured characters were the number of chromosomes, length of longest and shortest chromosomes, ratio of the longest to the shortest chromosome, the mean length of long arm to short arm of chromosomes, mean length of chromosomes and karyotypic symmetry in each cultivar. The results showed that the base chromosome number was 12 and 2n=4x=48 for the studied cultivars. The type of chromosomes in all studied cultivars were metacentric, sub metacentric and sub telocentric. Karyotipic analysis of cultivars using relative length of the shortest chromosome (S%), total karyotipic shape (TF%) and the difference in the range of relative chromosome length (DRL) was performed. All cultivars were relatively symmetric. Comparison of relative length of the shortest chromosome (S%) and the difference in the range of relative chromosome length (DRL) showed that the resistant ‘Ramose’ and ‘Boren’ cultivars, had the most symmetric karyotype, and the susceptible ones including, ‘Agria’ and ‘Santé’ had the least symmetric karyotype. The other cultivars including ‘Shepody’ and ‘Milova’ were located at intermediate state.