Agriculture Reference
In-Depth Information
Experiments obtaining mutations and their applications in plants breeding have
attracted attention only after discovering high mutagen activity of ionizing radiation
in mushrooms [9, 10] and higher plants [11].
Rapoport [12-15] and Auerbah [16] discovered a lot of new highly active muta-
gens. In his further scientifi c works, starting from 1957 at the Institute of Chemical
Physics of the USSR Academy of Sciences, I.A. Papoport discovered another large
amount of highly active substances—supermutagens, which cause hundreds and thou-
sand times more mutations compared with nonorganic chemical compounds. Williams
[17] accentuates the importance of mutations for breeding, stating that plant breeding
is based on the defi nition and use of mutations that strengthen their characteristics in
the desired way.
Nowadays, hundreds of chemical compounds with mutagen properties are known.
Soyfer [18], while studying chemical mutagens action mechanism, discovered alkyl-
ate compound reaction with both nitrogen base and DNA phosphate groups. These
reactions can fi nally result in destroying purine base, which may cause spot mutation
and DNA sugarphosphatic skeleton breakage, which causes chromosome aberration.
Chemical mutagens are strong factors inducing changes in genetic material.
Primary damages of DNA molecules with chemical mutagens include disturbance
in molecule structure (acridine inclusion and phosphorus group alkylation), trans-
formation of DNA normal base into atypical one (either because of their chemical
modifi cation or because of their change in the process of replication on the struc-
tural analogue), and destruction of bases. These damages can be repaired, saved, or
transformed into new changes of molecules and exhibited through change of their
characteristics. Specifi city of these changes can exhibit in the initial physiological and
genetic effects: early or distant death of plants; growth and development slowdown or
stimulation; and frequency of chromosome reformation.
Induced mutations make a wide spectrum of forms by changing any agricultural
and farm-valuable features of crops. That is why quite an easy way to work out the
weak points in plant breeding of any crop seemed possible. That is, a perspective of
improvement of single characteristic with simultaneous saving, the complex of other
useful practical characteristics in breeding varieties was considered. Yet, it turned out
that working out the weak points, that is to improve one or a few characteristics pos-
sible is not always possible. Mutation changes through mutation effect and other inter-
action of genes often envelop in the entire organism. As a result, undesirable agricul-
tural or breeding features may arise along with the newly developed ones.
Research aims. The research aims at detecting cytogenetic activity of chemical
mutagens depending on the genotype variety and proving the possibility of selection
and identifi cation of winter wheat lines of mutagen origin, selected for morphological
characteristics in generations of genetically unstable mutants.
23.2 MATERIALS AND METHODOLOGY
Investigated cytogenetic and mutagen action of eight alkylate DNA compounds: N -
nitozo- N -methyl urea (NMU), N -nitrozo- N -ethyl urea (NEU), N -nitrozodymethyl
urea (NDMU), dimethyl sulfate (DMS), diethyl sulfate (DES), nitrozomethylbiuret
(NMB), 1,4-bisdiazoacetylbutane (DAB), and ethylene imine (EI). The mutagens
 
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