Screening of promising olive cultivars and local genotypes for resistance to Verticillium dahliae in Iranian collection

Verticilliumwilt of olive (VWO) caused by fungus Verticillium dahliae, is one of the most important diseases of olive worldwide. The response of 15 promising olive cultivars and 15 local varieties was evaluated to the fungus. The olive saplings of each genotype were inoculated with suspension of the fungus using root dip method. The degree of susceptibility/resistance of each genotype was evaluated based on both morphological feature and quantification of fungus in the root system of different genotypes. Total DNA was extracted from root of saplings at different sampling intervals: 0, 2, 12, 45 and 80 days post inoculation. The gradual increase for DNA of fungus in saplings was quantified by Real-time PCR technique and utilizing of SYBR Green system with specific primer pairs for ß-tubulin2 gene. Based on both morphological and quantitative Real-time PCR assays: QG-11, DD2-1, treeNo2, PS-5 and Manzanilla were highly susceptible and KH-13, TTS-1, DS-5 code 5 Lorestan and DS-5 were evaluated as resistant genotypes to the VWO. Moreover, we found parallel results for conventional method of screening (based on disease symptoms) and quantification of DNA in root system of olive by Real-time PCR technique. Olive genotypes evaluated as highly susceptible or resistant to the disease in conventional method showed the similar reaction to the fungus in Q-PCR method. This may suggest that conventional method of evaluation for resistance could be replaced by Q-PCR molecular method in high thropout screening of olive germplasm.