Quantitative determination of a defoliating and non defoliating pathotype of Verticillium dahliae in susceptible and tolerant Greek olive cultivars

• Published in: Phytopathologia mediterranea Vol. 48; no. 2; p. 331
• Main Authors: Markakis, E A, Tjamos, SE, Antoniou, P P, Paplomatas, E J, Tjamos, E C
• Format: Journal Article
• Language: English
• Published: 01-08-2009
• Subjects: Olea; Verticillium; Verticillium dahliae
• ISSN: 0031-9465

Verticillium dahliae is the most serious olive disease in the Mediterranean countries and worldwide. The olive infecting pathotypes of V. dahliae have been classified as defoliating (D) and nondefoliating (ND) according to their ability to defoliate the tree. Verticillium wilt is mainly controlled in olive orchards by using resistant cultivars. However, limited information is available about the level and source of resistance in most of the olive cultivars and there are no published data using microsclerotia, the resting structure of V. dahliae, as the infective inoculum. In the present study, we quantified the biomass of a D and ND V. dahliae strain in the susceptible cv. Amfissis and the tolerant cvs Kalamon and Koroneiki, by using the Real Time PCR technology. The viability of the pathogen in the plant tissues was confirmed by isolating the fungus on PDA plates, while symptom assessment proved the correlation between the amount of V. dahliae in plant tissues and cultivar's susceptibility. It was demonstrated that the biomass of the D and ND strain was significantly higher in cv. Amfissis than in cvs Kalamon and Koroneiki. In addition, the biomass of the D strain was higher than ND in cv. Amfissis. It was also observed that the amount of the pathogen in roots is lower than in stems and shoots and declines over time.