Study of Genetic Variation in Isolates of Fusarium verticillioides (Sacc.) Nirenberg, the Causal Agent of Fusarium Ear Rot of Corn Using AFLP Markers

One hundred and eight isolates of Fusarium verticillioides, the causal agent of fusarium ear rot of corn collected from different geographic regions of Iran during growing season in 2005, and two standard tester isolates of F. verticillioides obtained from South Africa were chosen to be analyzed by AFLP markers to determine their genetic diversity. Total DNA of each isolate was extracted and digested by EcoRI and MseI endonuclease restriction enzymes and then digested fragments were ligated to site-specific double strands adapters. The products of a PCR reaction with non-selective primers were diluted and used in a selective PCR reaction applying five primer-pair combinations of MseI and P33 radioisotope labeled EcoRI. The final products of selective PCR were loaded and separated on a 5% polyacrylamide gel. The 98 polymorphic bands were scored manually and the dendrogram generated by UPGMA method based on Dice similarity coefficient as well as principal coordinate analysis (PCoA), grouped all of the F.verticillioides isolates into eight major clusters (A-H). The fingerprint group A with 98 members was the largest group and the other groups contained between one to three members. Based on the results of analysis of molecular variance (AMOVA) high genetic diversity was observed within each population and low genetic diversity was observed among all populations which it may be due to some variation factors such as mutation and gene or genotype flow