Résumé
The grapevine is a difficult species for genetic studies due to the plant size and long life cycle. With the microvine, these limitations can be overcome thanks to its dwarf stature, continuous flowering, short juvenile phase and generation cycle. The advantages of the microvine allow scientists to undertake genetic studies 2-5 times more rapidly than the current situation with normal grapevines. However, the seeds obtained from microvine parents have a low germination rate, and therefore some approaches to improve seed germination are required. Four microvine lines (ML1, V19, Pico x FLB 225, and AB x ML1) and a classical grapevine variety (‘Syrah’ cl. 174) were experimented in embryo rescue experiments. To evaluate embryo germination rate during berry development, seeds were collected from four different berry developmental stages including 2 weeks before veraison (WBV), veraison, 3 and 6 weeks after veraison (WAV). For all microvine varieties, the age of seed or berry stage influenced the development of the embryos. The highest percentage of germinating embryos (100 %) and normal developed plantlets (100 %) were recorded at veraison stage followed by 2 WBV, 3 WAV and 6 WAV, respectively. In addition, growth and development of embryos derived from veraison berries were also faster than the other phases. This study concluded that veraison is the most suitable berry developmental stage for microvine embryo extraction and culture, whereas, the best stage for embryo rescue in ‘Syrah’ grapevine is 2 WBV. The information obtained from this experiment will be useful for microvine breeding programs and expand their germplasm base in the future.