In grapevine, seedless grapes are the result of two biological distinct processes: parthenocarpy and stenospermocarpy. The first one defines the seedlessness type that results in fruit growth without fertilization. In the stenospermocarpy, the embryo and endosperm development starts after fertilization, but the tissues degenerate prematurely, resulting in fruits with seed traces. Seedlessness has a significant agronomic worth to the development of new table grape cultivars adapted to the Brazilian environmental conditions. Therefore, understanding the regulation of gene expression associated with seed formation during fruit development becomes an essential prerequisite to the generation of new genetic improvement tools. The present work aims the discovery of gene pools differentially expressed during the initial development of seedless fruits of the Thompson cultivar, through representational difference analysis (RDA) and complementary-DNA amplified fragment length polymorphism (cDNA-AFLP). Fruits were collected every two weeks from the anthesis until the eighth week of development. Total RNA was purified and cDNAs, corresponding to each development stage, were synthesized. These cDNA populations are being used to obtain stage-specific subtracted libraries via RDA. At least 192 clones will be sequenced from each library. Resulting sequences will be organized in databases and analyzed using public available bioinformatic tools. For the cDNA-AFLP approach, eight combinations of primer-adapters EcoRI+3 e MseI+3 were ligated to the synthesized cDNAs. Following final PCR amplifications, polyacrylamide-gel electrophoresis were run in order to obtain a profile of fragments derived from transcripts of every developmental stage. Up to now, 120 products were successfully re-amplified from a total number of 124 primary fragments derived from such transcripts. Sequencing and annotation of the whole collection of candidate genes are being conducted.

Financial Support: CNPq, FAPERGS and EMBRAPA Uva e Vinho