(go
to KOMUGI Home) (go
to WIS List) (go
to NO.75 Contents)
Discussion
The genes kr1, kr2 and kr3, which control
wheat-rye crossability have been located on 5BL (Riley and Chapman
1967; Lange and Riley 1973; Sitch et al 1985), 5AL (Riley and Chapman
1967; Sitch et al 1985) and 5D (Krowlow 1970; Snape et al 1979; Sitch
et al 1985), respectively. In this study we further confirmed the
location of kr1 on 5B and kr2
on 5A of the test line J-11 and the effect of kr1 was
stronger than that of kr2. The existence of kr3 gene
on chromosome 5D of the line J-11 was confirmed by its very weak
effect on the crossability with rye only when this gene was analyzed
with Abbondanza monosomic lines.
More importantly, a new gene, kr4, which was discovered in
the special Chinese landrace, Sichuan White Wheat complex, by Yen et
al (1986) was localized on chromosome 1A. Both of our results from
monosomic analyses with Chinese Spring and Abbondanza monosomic lines
showed that the promoting effect of the kr4 gene on wheat-rye
crossability was stronger than that of kr2 but weaker that of
kr1.
Falk and Kasha (1983) reported that the lines that were
heterozygous on all the
kr loci were still able to cross with rye and thus concluded
that the suppress of the wheat-rye crossability by the Kr
genes was incompletely dominant over the kr genes. Their
conclusion was based on their regression of the crossability (y)
values against doses of Kr1(x1) and Kr2
(x2) , and found y=75.1-30.7 x1-12.6
x2.
Based on this regression equation, the wheat-rye crossability of a
Kr1kr1Kr2kr2 genotype would be 31.8%. This does not fit to
our data. Our results showed that, when analyzed with Abbondanza
monosomic lines, the
Kr1kr1Kr2kr2Kr3kr3Kr4kr4 genotype had a wheat-rye
crossability of only 2.1 %, which is not statistically different from
0%. Therefore, the Kr genes should be completely dominant over
the kr genes.
Our results showed that, in a hemizygous status, a kr gene was
more effective in the monosomic plant that were derived from
Abbondanza monosomic lines than in those that were derived from
Chinese Spring monosomic lines. The Abbondanza monosomic lines
contain only Kr
alleles and the
Chinese Spring monosomic lines have only kr
alleles. Besides
the hemizygous kr
allele on the
monosomic chromosome, the monosomic F1 plants involving
Abbondanza monosomic 1A, 5B, 5A or 5D line would be heterozygous at
other Kr-kr
loci. On the other
hand, all the monosomic F1 plants involving Chinese Spring
monosomic lines will have only kr
alleles.
Therefore, it seems that Krkr
heterozygous
loci might have promoting effect on other hemizygous
kr
loci. Alternatively,
a recessive krkr
locus might be
able to suppress the effect of a hemizygous kr
locus.
Acknowledgements
The authors thank very much Dr. Yang Yen for his careful reading
and helpful assistance in the preparation of the manuscript.
References
Backhouse WO (1916) Note on the inheritance of crossability. J Genet
6: 91-94.
Falk DE and Kasha KJ (1983) Genetic studies of the crossability of
hexaploid wheat with rye and Hordeum bulbosum. Theor Appl
Genet 63: 303-307.
Krowlow KD (1970) Untersuchungen uber die Kreuzbarkeit zwishen Weizen
und Roggen. Z Pflanzenzucht 64: 44-72.
Lange W and Riley R (1973) The position on chromosome 5B of wheat of
the locus determining crossability with rye. Genet Res, Camb 22:
143-153.
Lein A (1943) Die genetische Grundlage der Kreuzbarkeit zwischen
Weizen und Roggen. Zeitschr Indukt Abstamm VerebungsI 81: 28- 61.
Luo MC, Yen C and Yang JL (1989) The crossability of landraces of
common wheat in Sichuan with Aegilops tauschii and rye. J
Sichuan Agric Univ. 7: 77-81. (in Chinese with English summary)
Luo MC, Yen C and Yang JL (1990) Brief report: Screening and
Identifying of a new "Bridge Variety". J Sichuan Agric Univ. 7:
77-81. (in Chinese with English summary)
Riley R and Chapman V (1967) The inheritance in wheat of crossability
with rye. Genet Res, Camb 9: 259-267.
Sitch LA, Snape JW and Firmanm SJ (1985) Intrachromosomal mapping of
crossability genes in wheat Triticum aestivum). Theor Appl
Genet 70: 309-314.
Snape JW, Chapman V, Moss J, Blanchard CE and Miller TE (1979) The
crossability of wheat varieties with Hordeum bulbosum.
Heredity 42: 291-298.
Taylor JW and Quisenbrry KS (1935) Inheritance of rye crossability in
wheat hybrids. J Amer Soc Agron 27; 149-153.
Yen C, Dai DQ and Luo MC (1986) High compatibility resources of wheat
for genetic hybridization among Secale and Aegilops.
Proc Int Triticale Symp 42-52.
Zeven AC (1987) Crossability percentages of some 1400 bread wheat
varieties and lines with rye. Euphytica 36: 299-319.
<--Back
(go
to KOMUGI Home) (go
to WIS List) (go
to NO.75 Contents)