VviAPRT3 and VviFSEX: Two Genes Involved in Sex Specification Able to Distinguish Different Flower Types in Vitis

Abstract

Vitis vinifera vinifera is a hermaphrodite subspecies, while its ancestor, Vitis vinifera sylvestris, is dioecious. We have identified two genes that together allow the discrimination between male, female and hermaphrodite Vitis plants. The sex locus region on chromosome 2 was screened resulting in the discovery of a new gene, VviFSEX. The same screening revealed another gene, VviAPRT3, located in the sex region, that be used as a sex marker. Both genes are good candidates to be involved in flower sex differentiation in grapevine. To assess their role in sex specification, spatial and temporal expression analysis was performed. The expression of VviFSEX is detected in petals, stamens and carpel primordia of all flower types, making its putative function unclear; however, female plants display a single allele for this gene, while male and hermaphrodites display two alleles. On the other hand, the specific expression of VviAPRT3 in the carpel primordial of male plants suggests a possible role in the abortion of pistil structures. We propose a model to explain the carpel abortion in male flowers and the absence of stamen viability in female flowers. In addition, this work reinforces the presence of a sex locus on Vitis chromosome 2.

The genetic basis of sex determination in grapevines (Vitis spp.)

“…7b). This is consistent with a previous study which showed that APT3 overexpression was specific to carpel primordia of sylvestris male flowers and led the authors to propose a role in carpel abortion (Coito et al, 2017). The ratio of expression between H/M and F alleles was predictably very low in female flowers which only contain the F allele, was low in hermaphrodite flowers, and was high in male flowers; the expression level or "dosage" of the APT3 H/M allele might influence sex determination (Extended Data Fig.…”

“…In grapevine, cytokinin application restores normal female organ development, producing berries from male grapevine flowers (Negi and Olmo, 1966). Interestingly, APT3 expression has been previously associated with the abortion of pistil structures in male grapevine flowers because of the high expression of the gene in the third and fourth whorl of male flowers (Coito et al, 2017). Fig.…”

“…The conservation of sex-linked sequences is remarkable, and consistent with the expectation of a sex determining region largely bereft of recombination. This work was made possible by the availability of diploid genomic information and significantly expands upon knowledge concerning the Vitis sex locus, which was previously limited to an estimation of its approximate coordinates(Fechter et al, 2012;Picq et al, 2014), the development of sex-specific markers, and whether one or more genomic features are involved in the determination of sex(Ramos et al, 2014;Coito et al, 2017).…”

RNA editing in inflorescences of wild grapevine unveils association to sex and development

“…Vitis is a perennial genus that in European countries has only one growing season, when it reiterates the development program allowing the analysis of the same plant on subsequent years. The present work in dioecious Vitis vinifera sylvestris (hereafter referred as V. v. sylvestris) lies in the difference between the two sexes: abortion of carpel development in male flowers and reflex stamens with non-viable pollen in female plants (Badouin et al, 2020;Coito et al, 2017;Massonnet et al, 2020;Picq et al, 2014;Zhou et al, 2017). We compared RNA edition events at several specific developmental stages, disclosing for the first time in plants, the twelve nucleotides modifications, previously detected in edited transcripts from human cells and cephalopods (Li et al, 2011;Liscovitch-Brauer et al, 2017).…”

The wild grape genome sequence provides insights into the transition from dioecy to hermaphroditism during grape domestication

“…Genetic analyses identified a 143-kb haplotype responsible for sex-determination in the grapevine reference genome 4, 5 . Two candidate genes for female sterility have been proposed, in particular APRT3 6 , a putative cytokinin regulator. However, the sequence of the sex locus was not available in V. sylvestris and no causative mutations have been identified.…”