Mutations in winter wheat (Triticum aestivum L.) under the dimethyl sulfate action

Abstract

The peculiarities of the chemical mutagen action and the induction of mutations during its interaction with the genotype of eight processed varieties and lines of winter wheat have been investigated. Chemical mutagen dimethyl sulfate (DMS) was used in concentrations of 0.125, 0.025 and 0.05% with an exposure time of 18 hours. The purpose of the study was to study the frequency and spectrum of mutations under the action of optimal for selective breeding practices of DMS, the selection of breeding and genetically valuable mutant lines for further use, identifying possible deviations under the action of mutagen depending on the method of obtaining the variety.

The total number of families in the second generation after mutagen treatment was 15,350. Mutations were detected by phenological observations and accounting in M₂ – M₃, followed by checking inheritance. Depending on the concentration of dimethyl sulfate, the mutation rate ranged from 18.0% (variety Khurtovina, DMS 0.05%) to 28.0% (variety Voloshkova, DMS 0.05%). The highest mutation rate was observed at a mutagen concentration of 0.05%. Both of these varieties showed greater mutability also under the action of lower concentrations of LCA. In general, the highest mutation rate was characteristic of winter wheat varieties obtained by the methods of hybridization and thermo-mutagenesis.

In the general spectrum of mutations, 36 signs were identified, according to which changes occurred under the action of dimethyl sulfate. For analysis, these characters were combined into groups: mutations of the structure of the stem and leaves; the intensity of the wax coating; color mutations and structure of the ear; color mutations and grain structure; mutations according to physiological signs of growth and development; system mutations; mutant families. It has been established that a characteristic distinguishing feature of dimethyl sulfate was a significant number of systemic mutations, sterile plants and mutants with a sign of short stature.

According to the results of studies, genetically and selectively valuable mutations were attributed, such as low-stem, semi-dwarf, large ears, large grain, early ripeness, productive families and plants. In general, the frequency of mutations on these characters was low (0.2–0.6%, depending on the genotype). 112 (24) low-stem mutants (especially from the Sonechko variety), 43 (18) semi-dwarfs, 18 (18) dwarfs, 5 (5) with large ears, 24 (5) early ripe were selected as genetically valuable mutants. It was noted that dimethyl sulfate, in contrast to the mutagens we previously studied, induced a significant number of dwarfs, but fewer positive mutations in terms of spike indicators.

Mutant lines with increased grain productivity were induced mainly at DMC concentration of 0.0125% with variation in the number of mutants from 0 to 0.6% in different genotypes. However, almost all such mutations were high stem, unstable to lodging and late ripening, therefore they were not promising. An exception was the Khurtovina variety under the action of DMC of 0.0125% (in further research line 179), which showed high productivity due to a higher mass of a thousand grains. Unfortunately, this mutant significantly exceeded its original shape in height.

It was established that with an increase in the concentration of dimethyl sulfate, a linear increase in the frequency of mutations and, in part, in the level of variability occurred. In general, a higher level of variability was characteristic of varieties obtained using hybridization and thermo-mutagenesis.

Thus, to obtain selection-valuable mutations in soft winter wheat plants, the use of dimethyl sulfate at a concentration of 0.0125% is recommended. To obtain more genetically valuable mutations, it is advisable to use a higher concentration of mutagen (0.05%). For the induction of semi-dwarf and dwarf forms, the use of higher concentrations of DMC is necessary.