Somaclonal variant UC-T3: the expression of Fusarium wilt resistance in progeny arrays of celery, Apium graveolens L.
First generation (S1) progeny, second generation (S2) progeny, and backcross (BC) progeny of a celery (Apium graveolens L. var. dulce) somaclonal variant, UC-T3, were evaluated for resistance to the fungus Fusarium oxysporum f. sp. apii, race 2 (FOA2). Chisquare analysis of S1 progeny showed that the expression of resistance did not fit a single-locus model. S2 progeny means were similar among families, except in a heavily infested field. The lowest ranking S2 family in both the lightly infested and heavily infested fields was significantly more resistant to FOA2 than individuals of the susceptible progenitor line 'Tall-Utah 527OR'; therefore; it was concluded that the trait was heritable. The phenotypic distribution of the backcross progeny was broad, suggesting that the new resistance was conferred by at least two genes whose expression was dominant to susceptibility. The mean scores for disease resistance of the progeny of crosses between UC-T3 and the moderately resistant line, 'Tall-Utah 527OHK', generally equaled the resistance found among the progeny of the most resistant parent.
Department of Vegetable Crops, Plant Growth Laboratory, University of California, 95616, Davis, CA, USA.
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Rappaport