Mani Awale, Dan Chitwood, Peter Cousins, Anne Fennell, Zach Harris, Misha Kwasniewski, Laszlo Kovacs, Jason Londo, Zoë Migicovsky, and Allison Miller*
*Saint Louis University, 3507 Laclede Avenue, St. Louis, MO, 63103-2010 (allison.j.miller@slu.edu)

Recent advances in high-throughput genomics and phenomics have enhanced the current understanding of how perennial crops sense and respond to their environ­ments over multiple years. Here, we used two grapevine grafting experiments to investigate how grapevine rootstocks interact with water availability to affect shoot system phenotype. First, an experimental vineyard in Mount Vernon, Missouri includes Chambourcin growing on its own roots or grafted to 1103P, 3309C, or SO4. We char­acterized multi-dimensional phenotypes in Chambourcin including berry chemistry, leaf shape, leaf ion concentration, leaf metabolites, and vine physiology, in part through hyperspectral imagery, and wine volatiles. There were complex interactions between rootstock and irrigation that shaped dynamic patterns of shoot system phe­notypes that varied across seasons and over years. Variation in ion (i.e., elemental) concentrations is also influenced by leaf position along the vine. Root system affected berry volatiles, in some instances with consistent trends across years. For instance, the mean β-damascenone present in own-rooted vines (9.49 μg/L) was significant­ly lower in other rootstocks (8.59 μg/L), while the mean linalool concentration was significantly higher in 1103P rootstock compared to own-rooted vines. Second, we explored the rootstock × scion interaction in a long-term study in California consisting of two grapevine varieties grafted to 15 different rootstocks. This study showed an >50% increase in yield, with changes in pruning weight and Ravaz index, by choos­ing the optimal rootstock, adding to the evidence that rootstock choice is crucial for grapegrowers looking to improve vine performance. These comprehensive, multi-year projects demonstrate the importance of root system variation for optimized shoot system morphology and suggest future exploration of rootstock genotypic diversity may offer an underutilized source of variation for shoot system phenotypic manipula­tion (e.g., vine productivity and berry chemistry) under changing climate conditions.

Funding Support: National Science Foundation