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Eur J Plant Pathol (2008) 122:549560 DOI 10.1007/s10658-008-9323-0
Novel methodologies in screening and selecting olive varieties and root-stocks for resistance to Verticillium dahliae
Polymnia P. Antoniou & Emmanouil A. Markakis &
Sotirios E. Tjamos & Epaminondas J. Paplomatas &
Eleftherios C. Tjamos
Received: 22 January 2007 /Accepted: 10 April 2008 /Published online: 13 May 2008 # KNPV 2008
Abstract An innovative inoculation process, involving the drilling of a trunk hole in 3 year-old olive trees and injecting a dense conidial suspension of Verticillium dahliae, was developed to study differentiation in foliar symptom expression between olive cultivars tolerant or susceptible to the pathogen. It was demonstrated that V. dahliae conidia could be translocated and colonize the xylem at the same distance above and below the point of trunk injection in both cultivars. However, the pathogen could be subsequently isolated at statistically significant percentages in susceptible cv. Amphissis compared to the tolerant cv. Kalamon, indicating operation of resistance mechanisms in the vascular phase of the disease. Consequently symptom development in the susceptible cultivar was at least sixfold more intensive compared to the tolerant cultivar, 611 months after trunk inoculation. Perennial olive orchard experiments, aimed at selecting Verticillium-resistant root-stocks, were conducted by applying the novel method in 23 year-old root-stock suckers of Amphissis olive trees and in the tolerant cvs Lianolia of Corfu and Koroneiki. It was indicated that potentially resistant root-stocks could be obtained following the trunk
drilling technique. Resistance differentiation between cvs Amphissis and Kalamon was further verified through root inoculation by various V. dahliae micro-sclerotial concentrations and demonstrated that the trunk drilling inoculation procedure is equally efficient in resistance evaluation of olives to Verticillium wilt. The trunk inoculation procedure could be useful in selecting and screening root-stocks for resistance toV. dahliae and other vascular pathogens and could elucidate resistance mechanisms in woody plants against vascular wilt diseases.
Keywords Olea europea . Trunk drilling inoculation . Verticillum wilt
Introduction
Olive (Olea europea) is considered as the most vulnerable tree host of Verticillium dahliae. Verticillium wilt occurs throughout the range of olive cultivation, substantially reducing the production of olive orchards and potentially causing tree death (Tjamos 1993; Hiemstra and Harris 1998; Jimenez-Diaz et al. 1998). Verticillium dahliae survives in the soil by means of microsclerotia that are...