Genotype contamination in seed production of maize inbred seed lots is not tolerated, i.e. the presence of only one seed from another genotype in a lot is sufficient to discard this lot. Many procedures have been studied to detect genotype purity in different crops, including molecular markers based on DNA polymorphism. This research aimed to evaluate the sensitivity of the microsatellite technique to detect the contaminating seeds in maize inbred lines. Four inbred lines (L1, L2, L3 and L4) were used. Samples of 100 seeds each of L1 were prepared considering L2 as a contaminant while seeds of L4 were contaminants in L3 seed lots. To simulate different contamination levels, 0, 1, 2, 5 and 10 seeds of the foreign genotype were mixed with the inbred line and then DNA was extracted from each treatment. Successive DNA samples dilutions of 0.01; 0.013; 0.02; 0.04; 0.1; 0.2; 1; 2; 5; 10 and 100% were also realized with to simulate low contamination levels. For both analysis microsatellites amplifications were performed with the primers BNLG125 for L1+L2 and BNLG240 for L3+L4. The results showed that the microsatellite technique is efficient to determine the varietal purity of inbred maize used in this research. The sensitive technique is able to detect a 0.01% DNA contaminant level. Standardization and intensity were better when a polyacrylamide matrix was used. The presence of foreign DNA in the contaminated lots was efficiently detected with the microsatellite technique, indicating the usefulness of this procedure to detect the presence of foreign seeds within maize inbred lots.
Zea mays; seed analysis; DNA markers
