Candidate genes within a 143 kb region of the flower sex locus in Vitis

Abstract

Wild Vitis species are dioecious plants, while the cultivated counterpart, Vitis vinifera subspec. vinifera, generally shows hermaphroditic flowers. In Vitis the genetic determinants of flower sex have previously been mapped to a region on chromosome 2. In a combined strategy of map-based cloning and the use of the publicly available grapevine reference genome sequence, the structure of the grapevine flower sex locus has been elucidated with the subsequent identification of candidate genes which might be involved in the development of the different flower sex types. In a fine mapping approach, the sex locus in grapevine was narrowed down using a population derived from a cross of a genotype with a Vitis vinifera background ('Schiava Grossa' × 'Riesling') with the male rootstock cv. 'Börner' (V. riparia × V. cinerea). A physical map of 143 kb was established from BAC clones spanning the 0.5 cM region defined by the closest flanking recombination break points. Sequencing and gene annotation of the entire region revealed several candidate genes with a potential impact on flower sex formation. One of the presumed candidate genes, an adenine phosphoribosyltransferase, was analysed in more detail. The results led to the development of a marker for the presence or absence of the female alleles, while the male and hermaphroditic alleles are still to be differentiated. The impact of other candidate genes is discussed, especially with regard to plant hormone actions. The markers developed will permit the selection of female breeding lines which do not require laborious emasculation thus considerably simplifying grapevine breeding. The genetic finger prints displayed that our cultivated grapevines frequently carry a female allele while homozygous hermaphrodites are rare.

Size and Content of the Sex-Determining Region of the Y Chromosome in Dioecious Mercurialis annua, a Plant with Homomorphic Sex Chromosomes

“…Plant species with homomorphic sex chromosomes so far investigated have been found to have a SDR < 1% of the total length of the Y chromosome, e.g., Vitis vinifera [44,45], several Populus species [46,47], and Fragaria chiloensis [48]. Mercurialis annua thus appears to have a particularly large SDR for a species with homomorphic sex chromosomes.…”

A small XY chromosomal region explains sex determination in wild dioecious V. vinifera and the reversal to hermaphroditism in domesticated grapevines

“…Several genetic maps based on interspecific crosses have confirmed that sex determinism in the genus Vitis is under the control of a single major genomic region located on chromosome 2, close to the SSR marker VVIB23 [15–17]. Recently, a complex interspecific cross ( V. vinifera x [ V. riparia x V. cinerea ]) was used by Fechter et al [18] to narrow the location of the sex locus to a 143 kb genomic region located between positions 4.907.434 and 5.037.597 bp of chromosome 2 [18] on the physical map of the V. vinifera reference genome sequence (PN40024 12x.0 version [19]). So far, the co-localisation on chromosome 2 of the sex locus in V. vinifera subsp.…”

“…Some of the processes involved in sex chromosome evolution, as the suppression of genetic recombination or the genetic degeneration of the Y chromosome, are not well understood and only the study of the sex-determining systems on different species and at different steps of evolution could provide some answers [23]. While the sex determination locus in Vitis species was mainly studied to develop genetic markers for early sexing for breeding purposes [18,20], the work of Fechter et al [18], evidencing a small sex-determination region, suggests that Vitis species could be good candidates to study the early steps of sex chromosome evolution.…”

Hybridization of cultivated Vitis vinifera with wild V. californica and V. girdiana in California

“…Two additional markers were used for flower sex determination: VVIb23 (Fechter et al. 2012) and APT3 (Battilana et al. 2013).…”