Variable inheritance of spinelessness in progenies of a mutant of the red raspberry cv. Willamette

Summary

The inheritance of spinelessness in progenies of a spine-free mutant of the red raspberry cv. Willamette was very variable. An hypothesis that the spinelessness is caused by a mutation to a dominant gene remains tentative, because, among progenies expected to segregate, some were entirely spiney, others were entirely spine-free and some segregated for spinelessness. Several possible causes of the variable segregation were apparently eliminated, but the recessive gene s, which also confers spinelessness, appeared to have a major effect on segregation. The possibilities are discussed that the diversity of segregation was caused either because the postulated mutant gene has pleiotropic effects on seed development similar to those of gene s, or because it is allelic to gene s. From a plant breeder's viewpoint the gene has limited value except for breeding purple raspberries.