Flower development and sex specification in wild grapevine

Abstract

BackgroundWild plants of Vitis closely related to the cultivated grapevine (V. v. vinifera) are believed to have been first domesticated 10,000 years BC around the Caspian Sea. V. v. vinifera is hermaphrodite whereas V. v. sylvestris is a dioecious species. Male flowers show a reduced pistil without style or stigma and female flowers present reflexed stamens with infertile pollen. V. vinifera produce perfect flowers with all functional structures. The mechanism for flower sex determination and specification in grapevine is still unknown.ResultsTo understand which genes are involved during the establishment of male, female and complete flowers, we analysed and compared the transcription profiles of four developmental stages of the three genders. We showed that sex determination is a late event during flower development and that the expression of genes from the ABCDE model is not directly correlated with the establishment of sexual dimorphism. We propose a temporal comprehensive model in which two mutations in two linked genes could be players in sex determination and indirectly establish the Vitis domestication process. Additionally, we also found clusters of genes differentially expressed between genders and between developmental stages that suggest a role involved in sex differentiation. Also, the detection of differentially transcribed regions that extended existing gene models (intergenic regions) between sexes suggests that they may account for some of the variation between the subspecies.ConclusionsThere is no evidence of differences of expression levels in genes from the ABCDE model that could explain the shift from hermaphroditism to dioecy. We propose that sex specification occurs after floral organ identity has been established and therefore, sex determination genes might be having an effect downstream of the ABCDE model genes.For the first time a full transcriptomic analysis was performed in different flower developmental stages in the same individual. Our experimental approach enabled us to create a comprehensive catalogue of transcribed genes across developmental stages and genders that will contribute for future work in sex determination in seed plants.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-1095) contains supplementary material, which is available to authorized users.

Plant contributions to our understanding of sex chromosome evolution

“…However, genes that control floral organ identity are not generally promising candidates. They might be involved in species with complete absence of one sex organ ('Type I' of Mitchell & Diggle, 2005;Ramos et al, 2014). In many dioecious plants, however, both male and female floral organs are initiated in flowers of both sexes, and the development of opposite sex organs is later interrupted.…”

Identification of a Vitis vinifera endo‐β‐1,3‐glucanase with antimicrobial activity against Plasmopara viticola

“…Sixty-five grapevine RNA-Seq raw data sequence files generated within the framework of seven different experiments (Da Silva et al, 2013;Jones et al, 2014;Perazzolli et al, 2012;Ramos et al, 2014;Sweetman et al, 2012;Vannozzi et al, 2012;Venturini et al, 2013) were retrieved from the National Center for Biotechnology Information (NCBI) SRA public database (http://www.ncbi.nlm.nih.gov/sra). Data were formatted in the fastq format using the fastq-dump command from the SRA Toolkit package version 2.3.4 (http://www.ncbi.nlm.nih.gov/books/NBK158900).…”

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

“…Structures for both sexes are present in wild grapevine dioecious flowers, though male flowers have reduced pistils and female flowers produce infertile pollen. Earlier work on grapevine sex determination proposed that sex determination occurs after floral organ identity is established (Ramos et al, 2014). Together, the existing literature supports that extant wild Vitis are likely derived from hermaphroditic ancestors and that dioecy results from independent and sequential male and female sterility mutations, as is predicted for angiosperms generally (Charlesworth and Charlesworth, 1978).…”

“…The proposed mechanism of sex determination is compatible with that proposed by Oberle et al (1938) involving a dominant allele inhibiting femaleness and a recessive allele inhibiting maleness. These two alleles have been designated So and sp, respectively, in keeping with the convention proposed by Oberle (1938) and reiterated by Ramos et al (2014). M-linked polymorphisms occurred in regions spanning the PPR-containing protein's promoter through an aldolase-coding gene and F-linked polymorphisms spanned TPP through APT3 (Fig.…”