Multilocus Sex Determination Revealed in Two Populations of Gynodioecious Wild Strawberry, Fragaria vesca subsp. bracteata.
Gynodioecy, the coexistence of females and hermaphrodites, occurs in 20% of angiosperm families and often enables transitions between hermaphroditism and dioecy. Clarifying mechanisms of sex determination in gynodioecious species can thus illuminate sexual system evolution. Genetic determination of gynodioecy, however, can be complex and is not fully characterized in any wild species. We used targeted sequence capture to genetically map a novel nuclear contributor to male sterility in a self-pollinated hermaphrodite of Fragaria vesca subsp. bracteata from the southern portion of its range. To understand its interaction with another identified locus and possibly additional loci, we performed crosses within and between two populations separated by 2000 km, phenotyped the progeny and sequenced candidate markers at both sex-determining loci. The newly mapped locus contains a high density of pentatricopeptide repeat genes, a class commonly involved in restoration of fertility caused by cytoplasmic male sterility. Examination of all crosses revealed three unlinked epistatically interacting loci that determine sexual phenotype and vary in frequency between populations. Fragaria vesca subsp. bracteata represents the first wild gynodioecious species with genomic evidence of both cytoplasmic and nuclear genes in sex determination. We propose a model for the interactions between these loci and new hypotheses for the evolution of sex determining chromosomes in the subdioecious and dioecious Fragaria.
Department of Biological Sciences, University of Pittsburgh, Pennsylvania 15260 tia1@pitt.edu.
Tia-Lynn
TL
Ashman
Department of Integrative Biology, Oregon State University, Corvallis, Oregon 97331.
Jacob A
JA
Tennessen
Department of Biological Sciences, University of Pittsburgh, Pennsylvania 15260.
Rebecca M
RM
Dalton
Department of Biological Sciences, University of Pittsburgh, Pennsylvania 15260.
Rajanikanth
R
Govindarajulu
Department of Biological Sciences, University of Pittsburgh, Pennsylvania 15260.
Matthew H
MH
Koski
Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331.
Aaron
A
Liston
D003433:Crosses, Genetic; D031985:Fragaria / Q000145:classification* / Q000235:genetics*; D005828:Genetics, Population; D018745:Genome, Plant; D023281:Genomics; D005838:Genotype; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D019849:Sex Determination Processes / Q000235:genetics*
Fragaria; dioecy; gynodioecy; male sterility; sex determination