title: Physiological and transcriptomic characterization of submergence and reoxygenation responses in soybean seedlings.
abstract: Complete inundation at the early seedling stage is a common environmental constraint for soybean production throughout the world. As floodwaters subside, submerged seedlings are subsequently exposed to reoxygenation stress in the natural progression of a flood event. Here, we characterized the fundamental acclimation responses to submergence and reoxygenation in soybean at the seedling establishment stage. Approximately 90% of seedlings succumbed during 3 d of inundation under constant darkness, whereas 10 d of submergence were lethal to over 90% of seedlings under 12 h light/12 h dark cycles, indicating the significance of underwater photosynthesis in seedling survival. Submergence rapidly decreased the abundance of carbohydrate reserves and ATP in aerial tissue of seedlings although chlorophyll breakdown was not observed. The carbohydrate and ATP contents were recovered upon de-submergence, but sudden exposure to oxygen also induced lipid peroxidation, confirming that reoxygenation induced oxidative stress. Whole transcriptome analysis recognized genome-scale reconfiguration of gene expression that regulates various signalling and metabolic pathways under submergence and reoxygenation. Comparative analysis of differentially regulated genes in shoots and roots of soybean and other plants defines conserved, organ-specific and species-specific adjustments which enhance adaptability to submergence and reoxygenation through different metabolic pathways.
authors.affiliation: Department of Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA, 24061, USA.
authors.forename: Bishal G
authors.initials: BG
authors.lastname: Tamang
authors.forename: Joseph O
authors.initials: JO
authors.lastname: Magliozzi
authors.forename: M A Saghai
authors.initials: MA
authors.lastname: Maroof
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fukao
mesh_terms: D000222:Adaptation, Physiological; D000255:Adenosine Triphosphate / Q000032:analysis; D002241:Carbohydrates / Q000032:analysis; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D015227:Lipid Peroxidation; D020411:Oligonucleotide Array Sequence Analysis; D009928:Organ Specificity; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000502:physiology; D018520:Plant Shoots / Q000235:genetics / Q000502:physiology; D018749:RNA, Plant / Q000235:genetics; D036226:Seedlings / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction; D013025:Glycine max / Q000235:genetics / Q000502:physiology*; D059467:Transcriptome; D014867:Water / Q000502:physiology*
chemical_list: D002241:Carbohydrates; D018749:RNA, Plant; D014867:Water; D000255:Adenosine Triphosphate; D010100:Oxygen
keywords: Affymetrix microarray; Glycine max; Group VII Ethylene Responsive Factors; flooding; genome-scale gene expression analysis