CYTOGENETIC ACTIVITY OF NITROSOMETHYLUREA FOR WINTER WHEAT

Abstract

When monitoring the characteristics of the activity of a chemical supermutagen, such parameters as the general frequency of chromosomal disorders, the proportions of certain types of rearrangements, and the presence of certain types of aberrations are of particular importance. Purpose. To show the differences in cytogenetic activity according to the rate and spectrum of chromosomal rearrangements in the cells of the meristem of the primary root system for winter wheat at the first generation, to show the key parameters depending on the genotype and concentration. Methods. Seeds of 8 winter wheat varieties Balaton, Borovytsia, Zeleny Gai, Zoloto Ukrainy, Kalancha, Niva Odeska, Polyanka, Pochayna were treated with a solution of the chemical mutagen nitrosomethylurea (NMU) in concentrations of 0.0125 and 0.025%. Analysis of chromosomal aberrations was performed using light microscopy on preparations of mitoses of the tips of primary roots of winter wheat varieties at the late stage of metaphase and early anaphase. Results. In general, the cytogenetic activity of nitrosomethylurea was very high. We studied such indicators as the total frequency, fragments (single and double), bridges (also single – chromatid – and double – chromosomal), rarer aberrations such as micronuclei, lagging chromosomes. Cells with multiple chromosomal aberrations (complex) were taken into account separately. A significant increase in concentration affected all indicators, the difference by genotype was significant only for the number of cells with multiple rearrangements. The number of cells with two or more aberrations turned out to be a reliable and reliable parameter that reflects an increase in the concentration (dose) of the mutagen and the effect of the subject of action (variety). According to the model features, only the presence of complex aberrations differs for the genotypes, there is no reaction to all other indicators. Obviously, it was this part of the spectrum that caused changes in the general frequency of cytogenetic disorders, which affected the differences of the three varieties from the others in the nature of variability at the cellular level. Conclusions. The indicator of cells with multiple (complex) rearrangements gains more weight. The highest genetic affinity to the action of NMU was shown by the genotypes Zeleny Gai, Polyanka, Borovytsia. The behavior of others did not differ significantly. Concentrations should be attributed to the range of conditionally moderate – high. They are among the optimal from the point of view of induction of mutations in subsequent generations for all studied genotypes, which will be established during future field experiments on their identification and inheritance.