Flooding Stress Tolerance In Maize Seedlings.

Oxygen deprivation is the primary stress during flooding or submergence of plants. Millions of acres of corn and soybean are flooded periodically in the Midwestern United States leading to heavy economic losses. The CERES-Maize model predicts significant increasing annual crop damage, due to heavy precipitation and waterlogged soils, in the coming years and decades. Early seedlings are the most susceptible to flooding stress in maize and many other crops and also most likely to experience drowning due to prolonged/heavy rainfall in wet springs. In this presentation, we plan to discuss the early cellular events that trigger altered gene expression and, in turn, how the molecular responses shape a plant’s tolerance to flooding stress. Although glycolytic and fermentative pathway enzymes are essential for adaptation; their activities are not quantitatively correlated with flooding tolerance. Instead, tolerance to prolonged stress depends on the capacity of the genotype to quickly restore cellular ionic homoeostasis and mount whole plant modifications that help to recoup O₂-supply. Ongoing efforts are aimed at exploiting the genetic variability for flooding tolerance prevalent in maize and its wild relatives using genetic or molecular breeding approaches. We also present novel transgenic strategies that take advantage of our understanding of early events and molecular responses.