CHEMICAL MUTAGENESIS AS A METHOD OF BASELINE GENETIC DIVERSITY ENLARGEMENT IN PLANT BREEDING - Ecological Consequences of Increasing Crop Productivity - page 251

Molecules of mutagen while penetrating through cell membrane enter the meta-
bolic balance of organism and condition different disorders in the in-cell balance. As
chemical mutagens infl uence on viability is revealed more intensive on the fi rst stage
of growth and development of M 1 plants, we also studied intensity of roots growth
initially in the period of seed germination in laboratory conditions besides well-known
criteria of plant sensitivity to mutagens (fi eld germination of seeds, survival, and ste-
rility of plants).
By the treatment by mutagen, water penetrates the seed tissue fi rst, with mutagen
molecules to follow. Individual fi eld of mutagen molecules consists of main physical
and chemical constants and expects not only specifi c interaction with gene material
but also with structural elements of nucleo- and cytoplasm for each mutagen as well
[19].
Mutations arise as a result of mutagen interaction with cell genetic material. On
the way to this contact, mutagens interfere the metabolism balance and can cause dif-
ferent abnormalities of in-cell balance and injury of genome part. That is why the fi rst
processes that take place directly after seeds soaking in mutagen solution cause injury
on the cell level and violation in chromosome structure.
Chromosome aberrations are important in genetic variation, monitoring, and evo-
lution and are one of the main characteristics of mutagen genetic activity. We studied
the infl uence of six mutagens on fi ve varieties by frequency of chromosome aberra-
tions. Mutagens break a chromosome apparatus and normal behavior of mitosis in
initial roots cells. The violation frequency depends on the concentration of mutagen.
Direct relation was detected in all varieties and mutagens: chromosome aberration
frequency increases with the increase in mutagen concentration For example, NEU
0.0125, 0.025, of 0.5 percent concentration conditioned from 3.7 percent of chromo-
some aberrations in Illichivka variety to 6.4 percent—in Krasnodarska 46 one, from
8.2 percent in Illichivka variety to 10.9 percent in Polisska 70 one and from 14.1 per-
cent in Myronivska 25 variety to 18.7 percent in Illichivka, respectively. Ethylene im-
ine in these varieties conditioned more violations in chromosome structure compared
with other varieties (Table 23.1).
Mutagens also differ in their genetic activity. Thus, 0.05 percent NMB conditioned
from 18.2 ± 1.5 to 31.8 ± 1.8 percent in fi ve varieties, while DES of the same concen-
tration—only from 12.3 ± 1.3 to 16.7 ± 1.5 percent of chromosome aberrations. NMB
and EI revealed the highest activity by their infl uence on mitotic cell apparatus of all
the studied mutagens.
Mutagen activity is revealed uneven in different genotypes (Table 23.1). In Polisska
70, Krasnodarska 46, and Illichivka varieties, the highest percentage of chromosome
aberrations was conditioned with NMB 0.05 percent concentration while in the seed
of these varieties treated with NMB and EI 0.0125 percent EI concentration solution, it
conditioned violation of chromosome structure with higher frequency than with NMS.