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Wheat Information
Service
Number 72: 3-8 (1991)
Production
of D addition lines in tetraploid wheat: I. Cytology of
F1 and F2 hybrids involving tetraploid
and hexaploid wheats
A. K. Misra* and P. K. Gupta
Cytogenetics Laboratory, Department of Agricultural Botany,
Meerut University, Meerut -250 005, India
Introduction
Spontaneous transfer of traits from some alien species to wheat
under natural conditions has been established and some cultivated
varieties of wheat, particularly those grown in Europe and USSR, are
known to have whole chromosomes or segments of chromosomes from one
or the other alien source (Gupta 1979). While on one hand the
attempts to artificially incorporate such transfers have met with
success in many cases, on the other they have generated valuable
information regarding homoeologous relationships between wheat
chromosomes and chromosomes from several alien species.
In hexaploid bread wheat, addition lines that carry a pair of alien
chromosomes have been obtained using several related genera like
Aegilops, Haynaldia, Secale and Hordeum.
However, despite continued cultivation and utility, tetraploid wheats
have received little attention for such chromosome manipulations.
Joppa (1973) reported production of D genome substitution lines in
durum wheats by crossing nullisomic-tetrasomic plants of hexaploid
wheat with durum wheat. Yashvir and Kesavan (1979) obtained three
monosomic addition and one double monosomic addition plants by
selfing pentaploid hybrids produced by crossing hexaploid and
tetraploid wheats. Joppa and McNeal (1972) and Joppa et al (1979)
developed disomic addition lines for chromosomes 1D, 3D, 4D, 5D and
6D in durum wheat.
Since only limited work has been done towards production of addition
or substitution lines in durums, there is a need to attempt addition
or substitution of many more alien chromosomes to this crop. Such
work may also generate valuable basic material for exploitation in
wheat breeding programmes.
Materials and Methods
Reciprocal crosses were made between tetraploid wheat strains
DD-21, Jairaj and ED-1570 and hexaploid wheat strains Sonora-64 and
C-306. Nine F1 plants reached maturity. They were selfed
to obtain F2 progeny. Emerging ears were bagged to avoid
pollen contamination. Standard aceto-carmine squash technique was
used for cytological studies.
Results and Discussion
The data on chromosome associations at metaphase I of meiosis of
nine F1 plants are presented in Table1.
All the plants had expected number of chromosomes (2n = 35).
Mean number of bivalents ranged between 13.88 to 14.00. As expected,
the mode of the number of bivalents was 14. Mean number of ring
bivalents per cell ranged between 10.44 to 12.20, with 11 being the
most common number. For rod bivalents, mean/cell ranged from 1.80 to
3.52, with two modes (2 and
3). As expected,
number of univalents in all the cases was 7 (Fig.1A),
with the mean ranging between 7.00 and 7.24. The presence of a
quadrivalent in AD2 (5) in a very low frequency could be due to
homoeologous pairing or interchange heterozygosity.
In pentaploid F1 hybrids (2n = 35, 14" + 7'), the
gametic chromosome number is expected to range between 14 and 21.
Accordingly, the somatic chromosome number in F2 plants
was found to range between 28 and 42. However, since the aim of the
present experiment was to obtain disomic additions of D genome
chromosomes to tetraploid wheat, the plants with more than fifteen
bivalents were of no consequence.
* Present address:
Department of Botany, North-Eastern Hill University, Mayurbhanj
Complex, Nongthymmai, Shillong-793014, Meghalaya, India
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