ISSN 1022-7954, Russian Journal of Genetics, 2009, Vol. 45, No. 7, pp. 794–798. © Pleiades Publishing, Inc., 2009.
Original Russian Text © K.K. Sidorova, V.K. Shumnyi, M.N. Glyanenko, E.Yu. Vlasova, T.M. Mischenko, I.A. Aleksandrova, 2009, published in Genetika, 2009, Vol. 45, No. 7,
The results of numerous studies on experimental
mutagenesis have shown that an important feature of
induced mutations in higher plants is the recessive type
of many such mutations [1–5].
Dominant mutations are encountered in plants more
rarely than recessive mutations. The cases of the
appearance of dominant mutations are described in a
series of scientiﬁc publications [6–8].
In connection with the appearance of supermutagens
-nitroso-alkylurea, ethylmethanesulfonate, and others),
new data have been reported in the literature indicating
that dominant mutations arise with elevated frequency.
Note that this phenomenon was observed in both diploid
and polyploid plant species [9, 10].
Note that all data presented above on the mode of
inheritance of induced mutations in higher plants are
based on results obtained in study of morphological
mutants, in which overground traits (shoot, leaves, ears,
ﬂowers, etc.) are changed. Researchers have been
focusing on the study of symbiotic mutants induced in
leguminous cultures only in recent years.
Symbiotic mutants differed from original forms in
respect to the number and size of root nitrogen ﬁxating
nodules, the ultrastructure of bacteroid tissue of nod-
ules, activity of nitrogen ﬁxation, resistance to nitrates,
and the duration of active nitrogen ﬁxation period. The
spectrum of symbiotic mutants is studied in most detail
Results of genetic hybrid analysis showed that the
majority of symbiotic mutants, the same as the morpho-
logical mutants with respect to overground traits are
recessive. In general, they are nonnodulating forms,
with a small number of nodules and with ineffective
nodules, or supernodulating mutants. Approximately
40 symbiosis genes have been identiﬁed in recent years
using of induced pea mutants [17–20].
Symbiotic mutants that showed dominant inherit-
ance occur rarely. In our experiments, three dominant
symbiotic mutants were previously isolated . The
purpose of this work is to induce novel dominant sym-
biotic mutants of pea and determine their phenogenetic
MATERIALS AND METHODS
The pea cultivar Rondo served as initial material. Air-
dried seeds were exposed to chemical mutagen ethyl-
methanesulfonate (EMS) at a solvent concentration of
0.2%, exposition 12 h, pH of 6. Our previous studies con-
ducted on various pea cultivars showed that EMS was
most efﬁcient mutagen with respect to the frequency and
spectrum of morphological mutations, in comparison with
even such supermutagens as
methanesulfonate is a less toxic mutagen than
alkylureas, which were shown to negatively affect plant
germination, survival, and sterility in M1 .
Experiments were conducted in a hydroponic green-
house (ceramsite substrate) and in the ﬁeld. Plant
growth conditions were maintained according to the
standard method used for greenhouses of this type .
With consideration of the negative effect of high doses
of nitrogen on nodulation, we used only the start nitro-
gen dose (20% of the full dose) during the ﬁrst ten days
after seed germination in a nutrient solution. Plant
seedlings were inoculated during this period with the
strain 250a. Since the M1
plants are chimeric, mutants, including dominant ones,
were isolated in M2. The test for inheritance of symbi-
Study of Dominant Symbiotic Mutants of Pea
K. K. Sidorova, V. K. Shumnyi, M. N. Glyanenko, E. Yu. Vlasova,
T. M. Mischenko, and I. A. Aleksandrova
Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Division, Novosibirsk, 630090 Russia;
Received January 31, 2008
—Phenogenetic studies of four symbiotic hypernodulating mutants of pea (
from seeds of cultivar Rodno by chemical mutagen EMS were conducted. All mutants have improved symbiotic
traits, i.e., an increased number of root nitrogen ﬁxating nodules and high activity of nitrogenase. Symbiotic
traits were shown to be inherited dominantly. Mutants grown in the ﬁeld or in a greenhouse showed superiority
over the original cultivar in productivity. An important feature of hypernodulating mutants was found that is
responsible for the appearance of high-height productive plants in F
after crossing mutants and the original
cultivar. Constant lines retaining the ability for high-level production up to the F
generation were created based
on individual plants.