1022-7954/05/4105- © 2005 Pleiades Publishing, Inc.
Russian Journal of Genetics, Vol. 41, No. 5, 2005, pp. 529–532. Translated from Genetika, Vol. 41, No. 5, 2005, pp. 657–660.
Original Russian Text Copyright © 2005 by Mglinets, Osipova.
Small-sized or dwarf plants are known among many
cultured plants such as maize, rice, pea,
etc. The dwarf plants have reduced leaf blades, roots,
and lengths of internodes and culm. Plant dwarﬁsm is
sometimes accompanied by abnormalities in reproduc-
tive plant organs, resulting in male or (and) female ste-
rility. Genetic analysis of mutations leading to dwarf
plant formation showed that these mutations may be
in maize), semi-dominant (muta-
in Arabidopsis), and even dominant (mutations
in maize, mutation
) in rice)
[1–5]. In beet, the recessive monogenic mutation
that results in dwarﬁsm has been previously described
. This mutation leads to the formation of small roots
in ﬁrst-year plants, and after vernalization, these plants
produce ﬂower stem only several centimeters in length.
In the present study, we describe a beet mutation that also
leads to dwarﬁsm but has other phenotypic expression.
MATERIALS AND METHODS
Plant hybridization was conducted using controlled
crosses. Ten to ﬁfteen unopened ﬂowers were castrated
and isolated with parchment isolators. Three to four
days after that, they were pollinated with freshly col-
lected pollen and again covered with isolators until
complete ball maturation. The hybrid F
obtained by compulsory self-pollination of the F
plants using parchment isolators.
mutation that causes pollen grain aggrega-
tion into tetrads was observed on temporary prepara-
tions. For this purpose, several anthers were minced
with a pincette or a needle in a drop of acetic carmine
and placed under a cover slip. Several minutes after
that, the preparations were examined.
Classifying the plants as the chorianthous-synant-
hous (choricarpousness-symphycarpousness), the
plants lacking inﬂorescence consisting of more than
one ﬂower were assigned to the chorianthous group.
The plants with at least two-ﬂower inﬂorescence on the
central stem and ﬁrst-order branches were assigned to
synanthous ones. In the second hybrid generation, all
plants were clearly divided into two alternative
classes—chorianthous (choricarpous) and synanthous
(symphycarpous). No plants with intermediate pheno-
types were observed.
Description of the Mutation
The plants with the mutant phenotype were signiﬁ-
cantly smaller in size than normal beet plants (Fig. 1).
They have reduced leaf blades (Fig. 2), ﬂower stem,
and ﬂowers. The height of mutant plants ranged from
10 to 40 cm (21.8 cm on average). The ﬂowers were so
small that their structure could be examined only under
a binocular microscope. The mutant plants had male-
and female-sterile ﬂowers. Instead of anthers, these
ﬂowers contained stamina terminating with white for-
mations that became brown with time (Fig. 3). These
formations did not resemble anthers in shape. In addi-
tion, ﬂowers of the mutant plants lacked seedbuds. Near
the branch ends, the ﬂowers were growing more
densely (Fig. 4). Some of plants lacked ﬂowers. The
mutation differed in phenotype from the
described previously in beet . Therefore, the former
Analysis of Inheritance of the dw2 Mutation
The ﬁrst-generation hybrids were obtained from an
inbred population segregating for annual and biennial
, a New Mutation of Beet
A. V. Mglinets and Z. A. Osipova
Institute of Cytology and Genetics, Russian Academy of Sciences, Novosibirsk, 630090 Russia;
fax: (3832) 33-12-78; e-mail: firstname.lastname@example.org
Received April 26, 2004
—Twelve dwarf plants were found in the second hybrid generation of beet. The average height of
mutant plants was 21.8 cm, their leaf blades and ﬂowers were signiﬁcantly smaller than normal, and the plants
exhibited male and female sterility. This dwarﬁsm was shown to be caused by a mutation differing from that
previously described in beet, which is named
). The experimental evidence suggests that this muta-
tion appeared in one of the ﬁrst-generation plants. Based on plant phenotype in the ﬁrst hybrid generation and
the number of mutant plants in the second one, this mutation is suggested to be under recessive monogenic con-
trol of the
gene. The genotypic class segregation in the second hybrid generation indicates that the
gene is inherited independently of genes
that control choricarpousness, gene male sterility, and
pollen grain aggregation into tetrads.