A TEST OF ALLELISM BETWEEN TWO SOURCES OF RESISTANCE TO BACTERIAL SPECK OF TOMATO

Resistance to the bacterial speck pathogen Pseudomonas syringae pv. tomato in cultivar Ontario 7710 and in accession PI 126430 of the wild species Lycopersicon pimpinellifolium is dominant and monogenic.
A test of allelism was conducted to determine whether resistance in these lines is based on the same or different genes.

Crosses were made between Ontario 7710 and PI 126430 to obtain seeds of the F₁ and F₂ generations.
The F₁ hybrid was crossed to a susceptible line.
Plants were inoculated at the fourth leaf-stage with a suspension of P. syringae pv. tomato.
Ten days after inoculation, lesions were counted on all the leaves of the test plants.

Plants of the F₂ generation segregated for the classes resistant (symptomless) and susceptible (50–90 lesions per plant) in a 15:1 ratio.
Progenies of the testcross (F₁ x susceptible) segregated for resistance and susceptibility in a 3:1 ratio.
These data indicate that cultivar Ontario 7710 and accession PI 126430 carry different genes for resistance to bacterial speck of tomato.

Symposium on Tomato Production on Arid Land

M. Pilowsky, D. Zutra

https://doi.org/10.17660/ActaHortic.1986.190.68