Searching for sources of resistance to Verticillium wilt of olive in seedlings from the genus Olea
C. TRAPERO (1), C. M. Diez (1), L. Rallo (1), F. J. López-Escudero (1), D. Barranco (1). (1) University of Cordoba, Cordoba, Spain
Verticillium wilt of olive (<i>Olea europaea</i>), caused by the fungus <i>Verticillium dahliae</i>, is the most serious disease of this crop and affects it worldwide. The use of plant material resistant to the disease is one of the most efficient measures, although nowadays there is a lack of resistant genotypes. As <i>V. dahliae</i> is a soilborne fungus, the resistance to this pathogen could be provided by either the rootstock or the scion. Since 2008, a breeding program aimed to obtain plant material resistant to the disease is carried out in the University of Córdoba, Spain. It has been developed a method to screen a great number of olive genotypes for resistance to <i>V. dahliae</i> in the first step of this breeding program. This method involves the root-dip inoculation of young seedlings with a highly virulent isolate of the fungus, and their assessment under controlled conditions. Up to date, using this test more than 10,000 seedlings obtained from crosses between olive cultivars, wild olives genotypes and other <i>Olea</i> species and <i>O. europaea</i> subspecies have been screened for resistance to <i>V. dahliae</i>. Most of the evaluated genotypes were susceptible to the disease, but some of them have been selected as resistant. Interesting sources of resistance have been found in some wild olive genotypes and <i>O. exasperata</i> species, which could be used as resistant rootstocks to control the disease. Resistance to Verticillium wilt of olive appears to be quantitatively inherited.
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