New breeding frontiers: application of the CRISPR-cas9 system in grapevine (V. vinifera L.) and improvements in plant regeneration

The wine industry currently relies on a limited number of grapevine cultivars, comprised of numerous clones with slight differences in their viticultural, oenological, or stress-tolerance traits.

Vitis vinifera L., is considered one of the world’s most important cultivated fruit crops. In agriculture, bunch morphology is a grapevine-specific trait, which directly impacts fruit quality and health.
Bunch size, shape, and compactness are major aspects of bunch morphology, with the degree of compactness emerging as an important trait for grapevine genetic enhancement and vineyard management. The importance of this trait stems from its impact on disease susceptibility, berry ripening, and other grape quality properties. However, current knowledge of the genes controlling it remains limited.

The crossings of three wild Vitis species are commonly used as rootstocks in wine production worldwide. Factors such as disease resistance and vigor are most important for their selection.
With climate change extending drought conditions and water limitations, the selection of rootstocks conferring increased tolerance to drought takes on greater importance. Therefore, identifying Vitis species with improved drought tolerance and incorporating them into breeding programs could contribute to more resilient rootstocks under water limiting conditions. Furthermore, those species serve as a valuable resource to increase genetic variability of rootstocks. We hypothesize that species native to drier habitats will exhibit superior physiological performance under drought stress.

A Syrah/R99 vineyard in the Stellenbosch area was used. The vineyard is vertically trained and spaced 2.75 x 1.5 m in north-south orientated rows on terroir with Glenrosa soil and west-facing slope. Irrigation (to 100% field water capacity) treatments were applied at different development stages [all stages (including berry set stage); pea size; véraison; post-véraison]. Combined effects of water status and ripeness level were investigated. Preliminary results are presented.

There is currently a real need to improve and speed-up phenotyping in experimental set-ups to increase the number of modalities studied. Accurate information acquisition on plant status with high-throughput capacity is the main appeal of on-board systems.
A proximal sensing camera for a proxy of winter pruning weight was tested. We estimated the shoot volume of the vine by image analysis using algorithms that integrate the local shoot section area estimate along the shoot skeleton obtained by a morphological distance transform.
The study was carried out on the GreffAdapt experimental vineyard in Guyot simple training and a canopy management using vertical trellising. The planting density is 6250 vines/ha with a row spacing of 1.6×1m. Five scions grafted onto 55 rootstocks are present and the combination rootstock×scion is different every five plants.