Heterogeneity of segregation ratios from selfed progenies demonstrate polygenic inheritance for day neutrality in strawberry (Fragaria xananassa Duch.)

摘要

Selfed progenies were generated using 10 day-neutral genotypes from the University of California (UC) strawberry breeding program as parents and their offspring were classified for late-summer flowering response. The grandparents of each selfed progeny included one of four day-neutral genotypes and one of eight short-day genotypes. Under the null bypothesis of genetic control by a single locus with the allele for day-neutrality dominant to the allele for short-day flowering response, all of these day-neutral parent genotypes must be heterozygous and their selfed offspring were expected to fit a 3:1 ratio of day-neutral,: short-day phenotypes. The percentage of day-neutral offspring observed over all progenies was 70.9%, and was significantly smaller than the expected value of 75% (chi(1)(2), = 5.08, P < 0.02). The percentage of day-neutral offspring for individual progenies ranged from 41.4% to 84.8%, and highly significant heterogeneity was detected among progenies (chi(9)(2) = 40.3, P < 0.01). Selfed progeny means for the cumulative late-summer flowering score calculated using the day-neutral fraction of offspring varied from 1.31 to 2.35 and progeny means for the number of inflorescences per plant ranged from 3.5 to 9.9; these differences among progenies Were highly significant (P < 0.01). These observations can be used to conclusively reject the hypothesis that day.neutrality in this domestic strawberry population is controlled by a single locus.