Responses of Grapevine Rootstocks at Physiological, Biochemical, and Molecular Levels to Waterlogging Stress

This study investigated the tolerance mechanisms of grapevine rootstocks (SO4 and 101-14) to waterlogging stress during 28 days.Waterlogging severely impaired morphological traits (roots, height, stem, leaves) in both.However, SO4 exhibited significantly greater tolerance than the highly sensitive 101-14.Morphologically, SO4 maintained healthy leaves for 14 days (similar to controls), with damage only appearing after 21 -28 days, and developed adaptive adventitious roots despite browning.In contrast, 101-14 showed severe leaf damage (etiolation, chlorosis, wilting) by day 14, complete leaf abscission by day 28, and suffered root loss, necrosis, and disintegration.Physiologically and biochemically, SO4 maintained moderate gas exchange (stomatal conductance, transpiration, CO 2 uptake, photosynthesis) and better retained photosynthetic characteristics (carotenoids and chlorophyll).SO4 also activated antioxidant processes (SOD, CAT, POD, APX) earlier and more strongly, resulting in controlled levels of malondialdehyde and hydrogen peroxide, indicating lower levels of oxidative damage.Proline and sugars also increased more in SO4.Conversely, 101-14 experienced severe declines in these areas and exhibited the highest MDA/H 2 O 2 levels.A molecular analysis (qPCR) revealed that the distinct tolerance of SO4 involved significantly higher upregulation of seven stress-responsive genes related to anaerobic metabolism (ADH1), ROS homeostasis (RBOH, POD), protein/membrane stabilization (Stress-Induced Protein, LEA), and stress signaling (KEG, CML).This coordinated response underpinned SO4's sustained energy, efficient antioxidants, reduced oxidative damage, chlorophyll retention, and its maintenance of photosynthesis.The limited gene activation in 101-14 aligned with its physiological collapse.Therefore, the SO4 rootstock demonstrates superior adaptive capacity to waterlogging and is recommended for cultivation under such conditions.