Physiological and transcriptional responses of grapevine rootstocks to waterlogging stress

The physiological and molecular mechanisms underlying waterlogging tolerance in grapevine rootstocks remain poorly understood. This study aimed to investigate the growth responses, protective enzyme activities, endogenous hormone levels, and associated gene expression in grapevine rootstocks under waterlogging stress. ‘SO4’ grape rootstock plants were subjected to waterlogging for 2, 14, and 27 days, with conventionally cultivated plants serving as controls. Waterlogging stress increased the contents of H₂O₂, MDA, and IBA, as well as the activities of SOD, CAT, GR, and SDH in the leaves. In contrast, it reduced chlorophyll and carotenoid levels, along with JA content. Additionally, APX and NAD-MDH enzyme activities decreased after 2 days of waterlogging but increased by day 27. The contents of MeJA and ABA increased at 14 days but declined by day 27. At the molecular level, waterlogging stress induced the up-regulation of genes such as MnSOD , SDH , TAM , LOX , AOS3 , and DAD1 , while suppressing the expression of ADH1 , YUCCA4 , and ZEP . These findings suggest that waterlogging tolerance in grape rootstocks may be associated with elevated IBA content, enhanced activities of SOD, CAT, GR, and SDH, and up-regulated expression of genes including MnSOD , SDH , TAM , and DAD1 .