Articles
VARIATIONS IN RESPONE OF A NUMBER OF TOMATO GENOTYPES INOCULATED WITH FUSARIUM OXYSPORUM F. SP. LYCOPERSICI RACE 2
Article number
412_61
Pages
515 – 522
Language
Abstract
Plants sensitive or reistant to Fusarium oxysporum f. sp. lycopersici (FOL) were inoculated with FOL race 0 and 1 by submerging the roots in a suspension of propagules, following the technique recommended by the Union for the Protection of New Varieties of Plants (UPOV). Forty-seven days after the inoculations, the plants were inpected for the presence or absence of external symptoms of disease and for vascular necrosis.
In addition, we attempted to re-isolate FOL by culturing discs of stem taken from several levels of all plants, whether or not they showed symptoms.
As much as ten percent of the plants of some cultivars with allele I2 showed vascular necrosis and, consequently, some plants of these cultivars now used for commercial cultivations will be vulnerable to attacks of FOL race 1, even though they are accepted as resistant by UPOV. The cultivars with allele I-2 allowed both FOL fungus races 0 and 1 to colonise some plants and these survived without external symptoms, for at least 47 days after the inoculations.
Because of this, the presence of FOL race 0 or 1 in the upper xylem does not reliably indicate whether or not the genotypes inoculated have got allele I-2. The concept of resistance-tolerance is discussed in the context of the observed colonisations by FOL races 0 and 1 of the xylems of genotypes with allele I-2. We observed a discontinuous distribution of FOL races 0 and 1 in I-2/+ plants and this could be associated with possible difficulties of physical transport of microconidia within the xylem vessels.
In addition, we attempted to re-isolate FOL by culturing discs of stem taken from several levels of all plants, whether or not they showed symptoms.
As much as ten percent of the plants of some cultivars with allele I2 showed vascular necrosis and, consequently, some plants of these cultivars now used for commercial cultivations will be vulnerable to attacks of FOL race 1, even though they are accepted as resistant by UPOV. The cultivars with allele I-2 allowed both FOL fungus races 0 and 1 to colonise some plants and these survived without external symptoms, for at least 47 days after the inoculations.
Because of this, the presence of FOL race 0 or 1 in the upper xylem does not reliably indicate whether or not the genotypes inoculated have got allele I-2. The concept of resistance-tolerance is discussed in the context of the observed colonisations by FOL races 0 and 1 of the xylems of genotypes with allele I-2. We observed a discontinuous distribution of FOL races 0 and 1 in I-2/+ plants and this could be associated with possible difficulties of physical transport of microconidia within the xylem vessels.
Authors
M.C. Rodríguez, J. Tello, J. Cuartero
Keywords
Fusarium wilt, Lycopersicon esculentum, resistance, tolerance
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