Vitis vinifera sex genes: from the wild to the domesticated varieties

Doutoramento em Biologia / Instituto Superior de Agronomia

Vitis vinifera vinifera is a domesticated hermaphrodite plant subspecies, and one of the most important crops in the world, required for wine making among other products. Vitis vinifera sylvestris is a dioecious subspecies considered the wild ancestral of V. v. vinifera. The molecular mechanisms responsible for the shift between hermaphroditism to dioecy are largely unknown. Male flowers of V. v. sylvestris show a reduced non-functional pistil while female plants exhibit reflexed stamens with infertile pollen. Hermaphrodite flowers develop functional male and female organs. In this work, the transcriptome of the three flower types were sequenced, assembled and de-novo assembled in order to map specific V. v. sylvestris transcripts, therefore understanding the primary players and mechanisms which contribute to the shift in flower types. This approach allowed for the detection of specific transcripts that might be responsible for the arrest of sexual organs in V. v. sylvestris flower type. Additionally, through transcription levels and RNA location, it seems that the ABCDE model genes are not responsible for the shift from hermaphroditism to dioecism and therefore sex determination mechanism most likely occurs downstream of the onset of flowering genes. The chromosome 2 was also specifically screened since it could contain a putative sex locus responsible for plant flower type determination. This analysis resulted in the development of two marker genes able to early differentiate between flower types, one of those genes specifically expressed only in the male flower carpels. Several crosses between both Vitis subspecies showed that the gene markers can predict the segregation based on flower type. Also, the genomic region where these genetic markers are located seem to be responsible for flower determination. It was possible to observe, that for VviAPRT3 and VviFSEX male plants are heterozygous dominant while female plants are homozygous recessive

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