Potential of new genetic resources to improve drought adaptation of grapevine rootstocks

Abstract

Grapevines are grown mainly as grafts worldwide, but the rootstocks most commonly used were selected between the late 19th and early 20^th centuries and are based on reduced genetic diversity^[1]. In the context of climate change, it is indeed urgent to diversify the range of rootstocks with genotypes much more adapted to drier environments, than the existing ones^[2]. The aim of this study was to evaluate the potential of new genetic resources for grapevine rootstock breeding programs. For this purpose, 12 American and Asian wild Vitis species (3 to 5 accessions per species = 50 accessions) were evaluated for their rooting ability and drought response. The plants were submitted to different irrigation treatments (moderate water deprivation vs well-watered) in a phenotyping platform for one month. Evaluation of gas exchange related traits and vegetative growth was performed during the experiment. Rooting ability and root morphology at different developmental stages were also recorded using image analysis using Rhizovision and SmartRoot softwares. We used mixed models to estimate broad-sense heritability. We observed high genetic variation among and within species for root traits and aerial drought response. Genetic correlations between aerial traits in response to drought and constitutive root morphology allowed us to select interesting accessions to be used in breeding programs. The 50 evaluated accessions have been grafted in 2023 to evaluate the interactions with the scion when used as rootstocks.

Acknowledgements: This study was supported by funding from INRAE, the Nouvelle-Aquitaine region (project VitiScope) and the CNIV. We acknowledge Maria Lafargue, Cyril Hevin, Nicolas Hocquard and Jean-Pierre Petit for their help with the plant material preparation.

References:

1)  Riaz, S. et al. (2019) Genetic diversity and parentage analysis of grape rootstocks. Theorethical and Applied Genetics 132, 1847–1860.
2)  Marín, D. et al.(2021) Challenges of viticulture adaptation to global change : Tackling the issue from the roots. Australian Journal of Grape and Wine Research, 27(1), Article 1.