The concentration of the important plant hormone auxin changes under oxygen deficiency.

What is it about?

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 eects 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 dierence 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 eect 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

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Why is it important?

The concentration of the plant hormone IAA changes under anoxia and under re-oxygenation. It may depend on a change in auxin degradation and transport within the plants. External addition of IAA increases the plant survival under anoxia.

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