Indoleacetic Acid Levels in Wheat and Rice Seedlings under Oxygen Deficiency and Subsequent Reoxygenation

Abstract

The lack of oxygen and post-anoxic reactions cause significant alterations of plant growth and metabolism. Plant hormones are active participants in these alterations. This study focuses on auxin–a phytohormone with a wide spectrum of effects on plant growth and stress tolerance. The indoleacetic acid (IAA) content in plants was measured by ELISA. The obtained data revealed anoxia-induced accumulation of IAA in wheat and rice seedlings related to their tolerance of oxygen deprivation. The highest IAA accumulation was detected in rice roots. Subsequent reoxygenation was accompanied with a fast auxin reduction to the control level. A major difference was reported for shoots: wheat seedlings contained less than one-third of normoxic level of auxin during post-anoxia, while IAA level in rice seedlings rapidly recovered to normoxic level. It is likely that the mechanisms of auxin dynamics resulted from oxygen-induced shift in auxin degradation and transport. Exogenous IAA treatment enhanced plant survival under anoxia by decreased electrolyte leakage, production of hydrogen peroxide and lipid peroxidation. The positive effect of external IAA application coincided with improvement of tolerance to oxygen deprivation in the 35S:iaaM × 35S:iaaH lines of transgene tobacco due to its IAA overproduction.

Molecular Mechanisms of the 1-Aminocyclopropane-1-Carboxylic Acid (ACC) Deaminase Producing Trichoderma asperellum MAP1 in Enhancing Wheat Tolerance to Waterlogging Stress

“…IAA is one of the major phytohormones playing a crucial role in controlling the growth and development of plants. The previous study has demonstrated that exogenous IAA promoted wheat plant survival upon low oxygen and flooding by a reduction in electrolyte leakage and reactive species (singlet oxygen, hydroxyl radical, superoxide anion, and hydrogen peroxide), which cause damage to cellular organelles and induce toxicity and LPO ( Yemelyanov et al, 2020 ). Additionally, IAA can increase the abiotic stress tolerance through the provocation of gene expression, antioxidant enzyme activity, photosynthetic pigment accumulation, and osmoprotectant (proline) synthesis that act as a free radical scavenger, thereby overcoming oxidative stress ( Siddiqui et al, 2017 ).…”

The hypoxia–reoxygenation stress in plants

“…Hypoxia triggers the accumulation of auxins, whereas the subsequent reoxygenation rapidly reduces their levels to that of normoxic plants ( Yemelyanov et al , 2020 ). Increases in endogenous auxin levels are required to produce a long coleoptile phenotype of rice plants under submergence ( Nghi et al , 2020 ).…”

“…Increases in endogenous auxin levels are required to produce a long coleoptile phenotype of rice plants under submergence ( Nghi et al , 2020 ). Moreover, the increase in auxin levels by either exogenous treatment or enhanced biosynthesis led to an improvement of tolerance to O 2 deprivation ( Yemelyanov et al , 2020 ). A transcriptional rewiring of several components of indole acetic acid (IAA) and ABA signaling accompanied by increases in the content of fatty acids and related lipids, organic acids, amino acids, and secondary metabolites with antioxidant activity have been reported to occur during partial reoxygenation of apple fruits after hypoxic storage conditions ( Brizzolara et al , 2019 ).…”

The Role of Aquaporins in Plant Growth under Conditions of Oxygen Deficiency

“…There is information on the submergence-induced decline in the level of indoleacetic acid (IAA) in petioles of R. palustris [ 147 ]. At the same time, anoxia-induced accumulation of IAA in wheat and rice seedlings has been shown, as well as the relationship of plant tolerance with oxygen deprivation [ 144 , 148 , 149 ]. The role of auxins in the activation of shoot elongation during flooding has been discussed mainly in connection with the ability of this hormone to influence the accumulation of osmotically active substances and the extensibility of the cell wall [ 150 , 151 ].…”