Abstract
BACKGROUND: Waterlogging is one of the major abiotic stresses in barley and greatly reduces grain yield and quality. To explore the mechanism controlling waterlogging tolerance in barley, physiological, anatomical and transcriptional analyses were performed in two contrasting barley varieties, viz. Franklin (susceptible) and TX9425 (tolerant). RESULTS: Compared to Franklin, TX9425 had more adventitious roots and aerenchymas and higher antioxidant enzyme activities. A total of 3064 and 5693 differentially expressed genes (DEGs) were identified in TX9425 after 24 h and 72 h of waterlogging treatment, respectively, while 2297 and 8462 DEGs were identified in Franklin. The results suggested that TX9425 was less affected by waterlogging stress after 72 h of treatment. The DEGs were enriched mainly in energy metabolism, hormone regulation, reactive oxygen species (ROS) scavenging, and cell wall-modifying enzymes. Alcohol dehydrogenase (ADH) plays an important role in response to waterlogging stress. We found that HvADH4 was significantly upregulated under waterlogging stress in TX9425. Transgenic Arabidopsis overexpressing HvADH4 displayed higher activity of antioxidant enzymes and was more tolerant to waterlogging than the wild type (WT). CONCLUSIONS: The current results provide valuable information that will be of great value for the exploration of new candidate genes for molecular breeding of waterlogging tolerance in barley.