The Inheritance of Flower Types and Fertility in the Strawberry

Abstract

In a study of sterility in the strawberry begun by the writer in 1914, a portion of the work was directed toward determining the underlying factors causing "nubbins" or imperfectly developed berries. These are commonly produced from the tertiary and later flowers of the inflorescence of many cultivated varieties of strawberry and result in considerable loss of fruit toward the close of the picking season.A study of the fruiting habit of the wild American strawberries mid of the cultivated varieties proves conclusively that the production of nubbins is directly related to pistil sterility, and that pistil sterility is decidedly more prevalent on plants with certain flower types than on others (7). Therefore, since the question of fruitfulness in the strawberry is primarily one of sex, a thorough knowledge of the flower types and of their inheritance is essential to the strawberry breeder if his work is to be other than blind crossing and selecting for chance high-yielding clones.The work on the inheritance of flower types in the strawberry has been discontinued by the writer, but, as some facts have been determined, he presents the data obtained and the conclusions drawn from them. FLOWER TYPES IN THE STRAWBERRYIn the cultivated strawberry, pistillate and perfect flowers are commonly encountered. The pistillate flowers bear small abortive stamens which have never been observed by the writer to produce pollen. The pistils are generally very fertile, producing perfect fruits from most of'the flowers and comparatively few nubbins. The perfect-flowered varieties develop anthers which produce varying amounts of normal pollen. As a class, these varieties are less fertile than the pistillate varieties and produce a higher percentage of nubbins and of sterile or male flowers (7).The wild species of American strawberries may be divided into two types: those which bear only perfect flowers, as Fragaria americana, and those which are dioecious. The pistils of the former species are very fertile, and nubbins or sterile flowers are seldom seen. The dioecious types produce pistillate plants and plants which apparently are hermaphrodites but are in fact staminates. The pistils of the pistillate clones are usually fertile, but the pistils of the staminate clones are rarely so, and the few berries

High variability and disomic segregation of microsatellites in the octoploid Fragaria virginiana Mill. (Rosaceae)

“…Commonly, however, hermaphrodites fail to set fruit, and thus can be considered as functionally male (Staudt 1989;Ashman 1999). Sex determination is under nuclear control, with male sterility (femaleness) dominant to male fertility (Valleau 1923;Ahmadi and Bringhurst 1989). F. virginiana is octoploid (2n=56) and is believed to have arisen from an ancient allo-autopolyploidization.…”

Constraints on the Evolution of Males and Sexual Dimorphism: Field Estimates of Genetic Architecture of Reproductive Traits in Three Populations of Gynodioecious Fragaria Virginiana

“…Populations vary in the frequency of females, and females produce the majority of the seed in populations in northwestern Pennsylvania (Ashman 1999a). Sex determination is under nuclear control, with male sterility (femaleness) dominant to male fertility (Valleau 1923;Ahmadi and Bringhurst 1989). Although F. virginiana has a polyploid origin, it currently behaves cytogenetically like a diploid (Bringhurst 1990;Ashley et al 2003).…”

Targeted Sequence Capture Provides Insight into Genome Structure and Genetics of Male Sterility in a Gynodioecious Diploid Strawberry,Fragaria vescassp.bracteata(Rosaceae)

“…ssp. bracteata concluded that female function is determined by a disomically inherited single nuclear locus (Valleau 1923; Ahmadi and Bringhurst 1989) in all three species with male sterility dominant, that is, females are heterozygous and hermaphrodites are homozygous at this locus.…”