• Identification of clone x rootstock effects on cold hardiness and relevant dehydrins changes in Cabernet franc (Vitis vinifera L.)

      Zhang, Linxue; Department of Biological Sciences
      Cold injury can harm grapevines and severely reduce yields in cool-climate regions. Previous studies indicate bud cold hardiness differences among Vitis vinifera cultivars, but comparatively, little attention has been given to the effect of clone and rootstock. This study investigates the bud cold hardiness of Cabernet franc with different clones and rootstock combinations throughout dormancy during the stages of cold acclimation, maximum hardiness and deacclimation. The research also looks at the protein expression of dehydrins which may impact cold hardiness. Four clone × rootstock combinations of Cabernet franc (214 × 101-14, 327 × 101-14, 327 × 3309, and 327 × Riparia Gloire) were assessed over two dormant seasons in 2018-19 and 2019-20. Buds were sampled every two to four weeks and were measured for cold hardiness by differential thermal analysis (DTA). Cold hardiness was reported as low temperature exotherms (LTE). Vine performance including phenological stages, yield components, vine balance, environmental resistance, and fruit composition including titratable acidity (TA), soluble solids, and pH were measured in 2019 and 2020. SDS-PAGE profiles and immunoblots measured dehydrins intensity during two dormant seasons in 2018-19 and 2019-20. Rootstock was found to impact cold hardiness of Cabernet franc. No significant differences were observed in bud hardiness between clones of Cabernet franc; despite significant differences in bud hardiness of clone × rootstock combinations of Cabernet franc. Dehydrin bands of five molecular weights (62 kDa, 57 kDa, 41 kDa, 30 kDa, and 23 kDa) were detected in the 2018-19 dormant season, and dehydrin bands of four molecular weights (62 kDa, 41 kDa, 30 kDa, and 23 kDa) were detected in the 2019-20 dormant season. The development of dehydrin bands varied for clones, rootstocks, and different molecular weights. No consistent correlations were observed between dehydrin intensity and LTE50 values, despite the increase of dehydrin intensity and the decrease of LTE50 values observed during acclimation. This study reveals the effect of clone and rootstock on cold hardiness, which is important for clone and rootstock selection in cool climate regions to reduce cold injury, and the complexity of the relationship between cold hardiness and dehydrins. In the future, studies should continue to focus on cold hardiness of clone and rootstock in different cultivars. Change of dehydrin levels during dormant seasons in more cultivars should also be studied to reveal the relationship between dehydrins and cold hardiness.