Cyclical assessment of superoxide anion-radical generation and characterization of linking physiological parameters in wheat (Triticum aestivum L.) seedlings

This study was conducted to evaluate the dynamics of superoxide anion radical (O 2) production rate and alterations in DNA content and permeability of cell membranes in etiolated wheat seedlings (Triticum aestivum L. cv. Harmony) as well as those grown under normal daylight regime. The results suggest that the development of etiolated wheat seedlings and those grown under normal daylight is accompanied by the periodic formation of O 2 which leads to alterations in DNA content as well as the permeability of cell membranes. The results also indicate that the first enhancement in the rate of O 2 generation was detected on the sixth and seventh days of development, after which the rate of O 2 ̄ production reduced in etiolated seedlings and those grown under normal daylight regime. The second maximum of the O 2 ̄ producing rate in developing and senescent organs occurred on the ninth day of plant development. The lowest values of all studied parameters, such as O 2 producing rate (37%), total genomic DNA concentration (58%) and electrolyte leakage (EL; 18%) were observed in etiolated wheat seedlings. Towards the end of the study period, DNA concentration and EL in organs of wheat seedlings declined, suggesting possible destruction of cellular organelles and the beginning of apoptotic processes. Overall, these results indicate that O 2 generation is decisive for normal morphogenesis, and it is an indispensable element of synchronous growth and development.