Direct versus indirect radiation action in irradiated vegetal embryos

Maize is one of model plants useful for genetic investigations and also very important for its agrotechnical utilizations. Here the genotoxic effects of low dose X-rays and accelerated electrons in maize caryopses was carried out with focus on the influence of water content at the moment of seed irradiation. X-ray photon beam as well as accelerated electrons were provided with 2.40 Gy min(-1) dose rate. Pre-soaked and dry maize caryopses were irradiated with 0.5-3.0-6.0 Gy. Cytogenetic investigations were carried out based on microscope observations of chromosomes stained by Feulgen method. The mitotic index was found diminished in hydrated samples indicating the negative influence of indirect effects of water radicals. As known the water radiolysis release free radicals that attack biomolecules in addition to the directly absorbed radiation impact. Slight positive influence of 0.5 Gy radiation dose on cell division was evidenced. Chromosomal aberrations were identified like: vagrand chromosomes, C-metaphases, picnotic chromosomes, chromatide bridges. General tendency of aberrant mitoses enhancing was recorded in watered samples - with up to the twice increase for 6.0 Gy radiation dose. The results evidenced the hydration role in monitoring cytogenetic effects of low dose radiations in plant systems -with possible biotechnological applications.