The Mechanisms Underlying Physiological and Molecular Responses to Waterlogging in Flax

Waterlogging due to excessive rainfall has become a factor limiting flax production in southern China. This has led to morphology alteration, and biomass and yield reduction in field crop production. Flax variety Zhongyama 1 was planted in sand culture, and the adaptive mechanisms of the responses to waterlogging in the fast growth and harvest stage were determined. According to the results, height and total biomass decreased significantly under waterlogged conditions during the fast growth period; furthermore, in the harvest stage, flax height increased significantly, whereas the technical length, fork diameter, and weight decreased significantly. For gene expression, the gene of glucose, glutathione metabolism, was up-regulated in shoot, and the gene of phenylpropanoid metabolic, lignin, was up-regulated in root. The results suggested that the synthesis and degradation of lignin is involved in flax resistance to waterlogging, especially in terms of phenylpropanoid biosynthesis, glycolysis, and metabolism of plant hormone signal transduction. Furthermore, unpaired electrons flowing through the electron transport chain may react with oxygen to produce ROS and hamper plant growth, development, and survival.