Chromosomal rearrangements caused by gamma-irradiation in winter wheat cells

M M Nazarenko,O O Izhboldin

doi:10.15421/011704

Abstract

In this article we report the results of our investigation into several cytogenetic parameters of variability in mutation induction of modern winter wheat varieties and some connections between the means of cytogenetic indices and different doses of gamma-rays. Analysis of chromosomal aberrations following the action of any kind of mutagen by the anaphases method is one of the most widely investigated and most precise methods which can be used to determine the fact of mutagenic action on plants and identify the nature of the mutagen. We combined in our investigation the sensitivity of genotype to mutagen using cytological analysis of mutagen treated wheat populations with the corresponding different varieties by breeding methods to reveal its connections and differences, specific sensitivity to mutagens action on the cell level. Dry seeds of 8 varieties of winter wheat were subjected to 100, 150, 200, 250 Gy gamma irradiation, which are trivial for winter wheat mutation breeding. We investigated rates and spectra of chromosomal aberrations in the cells of winter wheat primary roots tips. The coefficients of correlations amid the rate of chromosomal aberrations and the dose of gamma-rays were on the level 0.8–0.9. The fragments/bridges ratio is a clear and sufficient index for determining the nature of the mutagen agent. We distinguished the following types of chromosomal rearrangements: chromatid and chromosome bridges, single and double fragments, micronuclei, and delayed chromosomes. The ratio of chromosomal aberrations changes with the change in mutagen; note that bridge-types are characteristic of irradiation. Radiomutants are more resistant to gamma rays. This is apparent in the lower rate of chromosomal aberrations. Varieties obtained by chemical mutagenesis (varieties Sonechko, Kalinova) are more sensitive to gamma-irradiation than others. We propose these varieties as objects for a mutation breeding programme and radiation of mutants for planting in areas subject to the action of gamma-rays.

Highlights

There are three reasons for the study of plant mutant generation M1 after mutagenic effect
Winter wheat seeds (Triticum aestivum L.) of Favoritka, Lasunya, Hurtovina, line 418, Kolos Mironovschiny, Sonechko and Kalinova, Voloshkova were subjected to 100, 150, 200, 250
We found that repeated exposure to similar mutagens tends to produce a substantially lower rate of chromosomal aberrations

Summary

Introduction

There are three reasons for the study of plant mutant generation M1 after mutagenic effect. The second reason is the fact that the amount of material, obtained from the first generation, limits the opportunities for mutation breeding programmes (especially using lethal doses). The third reason is the use of obtained M1 population to extract valuable mutant strains in further generations. Mutagenesis reduces plant growth and other crop yield structural components, increases the sterility of pollen and reduces the germination and survival abilities of plants by means of chemical agents and gamma rays; sometimes the greater part of a population is killed by critical doses (Solanki and Sharma, 2000). Sometimes we observe a stimulating effect (in case of low doses) or absence of depression (at medium concentrations of some chemical mutagens). Positive desirable mutants can be selected and be incorporated in future breeding programmes (Ali Sakin et al, 2005)

Methods

Results

Conclusion