Articles
A MAPPING APPROACH TO DEFINE THE GENETIC STRUCTURE OF THE SEX-DETERMINING LOCUS IN THE DIOECIOUS SPECIES ACTINIDIA CHINENSIS
Article number
839_77
Pages
561 – 566
Language
English
Abstract
All species recorded in the genus Actinidia (kiwifruit) display XX/XY female/male sex chromosome dimorphism.
The sex chromosomes, however, have not been amenable to characterisation because of the high chromosome number, n = 29, and their very small, and similar, size.
Dioecy in the genus not only has implications for orchard management, but also in breeding programmes aimed at producing new and novel cultivars for the commercial market.
To get a better understanding of sex determination, we have developed a genetic linkage map in a population from an intraspecific cross of diploid A. chinensis. Dinucleotide microsatellites from expressed genes were the marker type of choice being co-dominant, highly polymorphic and frequently occurring in Actinidia. These attributes would be expected to increase marker utility within and across species.
Flower phenotype was mapped, together with sequence-characterised amplified region (SCAR) sex-linked markers, to identify the linkage group corresponding to the sex chromosomes.
A number of expressed sequence tag (EST)-derived microsatellite markers, indicative of functional genes, mapped in the same vicinity, but, because of a lack of recombination in this region, marker order was difficult to determine.
To develop a universal sex marker for use in breeding populations, an understanding of the linear order of markers and their relationship to the flower phenotype marker is necessary.
Additional information is being obtained for markers in the region from the use of appropriate backcrosses with the parents, progeny, and close relatives of the original mapping population.
The sex chromosomes, however, have not been amenable to characterisation because of the high chromosome number, n = 29, and their very small, and similar, size.
Dioecy in the genus not only has implications for orchard management, but also in breeding programmes aimed at producing new and novel cultivars for the commercial market.
To get a better understanding of sex determination, we have developed a genetic linkage map in a population from an intraspecific cross of diploid A. chinensis. Dinucleotide microsatellites from expressed genes were the marker type of choice being co-dominant, highly polymorphic and frequently occurring in Actinidia. These attributes would be expected to increase marker utility within and across species.
Flower phenotype was mapped, together with sequence-characterised amplified region (SCAR) sex-linked markers, to identify the linkage group corresponding to the sex chromosomes.
A number of expressed sequence tag (EST)-derived microsatellite markers, indicative of functional genes, mapped in the same vicinity, but, because of a lack of recombination in this region, marker order was difficult to determine.
To develop a universal sex marker for use in breeding populations, an understanding of the linear order of markers and their relationship to the flower phenotype marker is necessary.
Additional information is being obtained for markers in the region from the use of appropriate backcrosses with the parents, progeny, and close relatives of the original mapping population.
Authors
L.G. Fraser, G.K. Tsang, P.M. Datson, E. Hilario, H. Nihal De Silva, M.M. McNeilage
Keywords
kiwifruit, dioecy, genetic map, microsatellite markers, recombination suppression
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