EVALUATION AND INHERITANCE OF THE LYCOPERSICON-HIRSUTUM RESISTANCE AGAINST POTATO-VIRUS-Y

Potato virus Y (PVY) infects most Solanaceous crops grown in Mediterra nean countries in open fields and in greenhouses. Necrogenic strains, which have been isolated from diseased tomatoes in France since the 19 80's, seriously cause yield and quality loss of tomato fruits. Lycoper sicon hirsutum PI 247087 was found to be resistant to PVY. Virus could not be detected in inoculated leaves by ELISA and/or by back-inoculat ion on susceptible plants. This resistance was efficient against the 1 6 tested isolates or strains. Temperature and inoculum concentration d id not affect its expression. All the F-1 plants of (Momor x PI 247087 ), (PI 134417 x PI 247087) and (PI 247087 x PI 134417) had symptom sco res and ELISA values similar to those of the susceptible parents. The mechanism of resistance could be immunity-like or inhibition of virus migration from cell to cell. The resistance of L. hirsutum PI 247087 a ppeared to be governed by two independent recessive genes. In a few F- 2 plants of(PI 134417 x PI 247087) and F-2 (Momor x PI 247087), virus was able to multiply in the inoculated leaves but could not establish a systemic infection. This finding may suggest a mechanism which inter fers with the long distance migration of the virus in the plant.