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Wheat Information
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Number 71: 6-9 (1990)
Mutation
of five marker genes in wheat by the gametocidal gene of
Aegilops speltoides, Gc1a
H. Tsujimoto and K. Noda
Kihara Institute for Biological Research, Yokohama City
University, Mutsukawa 3-122-20, Minami-ku, Yokohama 232, Japan.
Summary
A common wheat line carrying the gametocidal gene, Gc1a,
originating from Aegilops speltoides was crossed to a line
carrying five dominant marker genes. In the F1 generation
of the cross using the Gc1a carrier as a male parent,
unexpected plants which lacked expression of one or two marker
characters appeared. Only a few mutations were observed in the
reciprocal cross. Moreover, most of the mutants observed in the
F1 plants of the former cross were not chimeric. These
findings indicate that in the former cross, the marker genes derived
from the female gametes were mutated by the gametocidal gene of the
male gamete in the first zygotic cell.
Introduction
Many papers have reported that gametocidal genes of wheat
relatives can induce chromosomal mutation. Recently, Endo (1990)
published a review on this phenomenon and in it he classified the
chromosomal mutations into two groups, that is, mutations induced in
gametes and those in zygotes. The zygotic mutation was first observed
by Tsujimoto and Tsunewaki (1985) in the F1 generation of
crosses between various euploid common wheat cultivars and a common
wheat line carrying the gametocidal gene of Aegilops
speltoides (Gc1a) in the homozygous condition. Because the
line of Gc1a homozygote did not manifest abnormal gametes, it
was clear that the mutation observed in the F1 must have
been induced in the F1 zygotes.
To make the feature of the zygotic mutation caused by Gc1a
clearer, we made crosses between a line carrying five dominant marker
genes and the line carrying the Gc1a and observed the
expression of the marker genes in the F1 plants.
Materials and Methods
The line carrying the gametocidal gene, Gc1a, originating
from Aegilops speltoides in the background of
Triticum aestivum cv. 'Chinese Spring' was crossed to a wheat
line carrying five dominant marker genes in the background of
cultivar 'S-615', and phenotypes of the F1 plants were
observed. The marker genes of the marker line and their chromosome
locations are: B1(5Aq) for awn suppression, Q (5Aq) for
speltoid suppression, C (2Dq) for compact spikes, Hg
(1 Ap) for hairy glumes, and Hp1 (4Aq) for hairy
necks. On the other hand, the gametocidal gene carrier (abbrev.
CS-Gc1aGc1a) has recessive alleles of B1, C, Hg and
Hp1 and a dominant allele of Q, i.e., the genotypes is
b1b1 QQ cc hghg hp1hp1. Therefore, the F1 plants
should have a genotype of B1b1 QQ Cc Hghg Hp1hp1. If a
mutation occurred, the dominant Phenotype would disappear in the
F1. Regarding Q, speltoid spikes will appear when
dose of Q decreases from the normal two to one, therefore, the
mutation is also recognized in the F1.
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