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.
Highlights
Plant growth is a complicated process under the control of multiple internal and external effectors
A major difference was reported for shoots: wheat seedlings contained less than one-third of normoxic level of auxin during post-anoxia, while indoleacetic acid (IAA) level in rice seedlings rapidly recovered to normoxic level
Rice roots and shoots accumulated about the same amount of free IAA. 12 h of anoxic treatment (12+0 point) led to a rise of IAA level by 50% in wheat shoots (Figure 1a) which was maintained until 6 h of reoxygenation followed by a significant decrease to about 20%–30% of normoxic and 10% of anoxic level
Summary
Plant growth is a complicated process under the control of multiple internal and external effectors. Plant response is always the sum of positive and negative alterations appearing at molecular, cell, tissue and organism levels. Nowadays modeling provides an efficient way to elucidate systemic plant response [1]. Each of the stressors has peculiar mechanisms of action involving activation of specific gene groups that trigger specific developmental, physiological and metabolic adaptations. Accumulated data suggest that there are possible integrative responses common for a group of factors, such as drought, salinity and chilling stress [2]. We aim to reveal some cross-adaptations to oxygen deficiency and further reoxygenation
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