Cucurbit Genetics Cooperative Report 3:12-13 (article 7) 1980
Complementation Between Two Perfect Flowered Mutants in
Cucumber
A.F. Iezzoni and C.E Peterson
University of Wisconsin, Madison, WI 53706
G.E. Tolla
Campbell Institute
of Agricultural Research, Napoleon, OH 43545
In 1928, Rosa reported simple inheritance for flower type
in cucumber: M/- plants have pistillate flowers
and m/m plants have perfect flowers. Over
the past several years, we have developed perfect flowered
lines from backcrossing programs using two sources of the
perfect flowered gene. The sources were the American cv.
'Crystal Apple' and a Polish breeding line from Kubicki.
Both of these lines showed the characteristic clusters of
perigynous perfect flowers with small rounded ovaries. When
lines derived from the same m/m source
are crossed, the prefect flowered phenotype is observed.
However, when two perfect flowered lines originating from
different sources are crossed, the F1s have one epigynous
long ovaried pistillate flower per node. This appears to
be a classical example of genetic complementation in which
two mutants are crossed and the wild type phenotype is obtained.
we have arbitrarily assigned the 'Crystal Apple' derivatives
allele m1 and those from
the Polish breeding line, m21. In this study, the apparent complementation between two
perfect flowered types was investigated. The simply inherited
dominant gene for bacterial wilt resistance which is tightly
linked to the M/m1
locus (~1% CO) was used as a genetic marker.
Two different crosses which exhibited complementation in
the F1 were investigated in the F2 and BC1 populations. In
the F2 population, a 1 perfect:1 pistillate flowered plant
ratio was obtained (Table 1). The perfect flowered types
could further be separated into bacterial wilt resistant
or susceptible plants which indicates whether they are homozygous
for m1 or m2.
Upon backcrossing to the susceptible parent, a 1 perfect:1
pistillate flowered plant ratio was obtained and as expected,
all the perfect flowered types were susceptible and all
the pistillate types were resistant (Table 2).
Both flower type and ovary shape show complementation.
Unfortunately, this system does not lend itself to further
analysis of the chromosome segment. Therefore, it is impossible
to conclude whether the m1 and m2 mutants represent
different genes (non-allelic complementation) or whether
they are different mutational sites within the same gene
(allelic complementation).
1 This nomenclature is temporary and will be revised following
further investigation.
Table 1. F2 data from two populations exhibit complementation
in the F1.
|
(m1Bw/m2/bw) |
|
Phenotype |
Genotype |
Population A |
Population B |
Perfect, resistant |
m1Bw/m1Bw |
91 |
83 |
Pistillate, resistant |
m1Bw/m2bw |
204 |
160 |
Perfect, susceptible |
m2bw/m2bw |
87 |
71 |
Total |
|
382 |
314 |
X2 (1:2:1) |
|
1.85 |
1.03 |
Probability |
|
25-50% |
50-75% |
Table 2. BC1 data from two populations exhibiting complementation
in the F1.
|
(m1Bw/m2bw)
x (m2bw/m2bw) |
|
Phenotype |
Genotype |
Population A |
Population B |
Pistillate, resistant |
m1Bw/m1bw |
21 |
67 |
Perfect, susceptible |
m2bw/m2bw |
29 |
51 |
Total |
|
50 |
118 |
X2 (1:1) |
|
1.28 |
2.78 |
Probability |
|
20-25% |
5-10% |
Literature Cited
- Rosa, J.T. 1928. The inheritance of flower type in
Cucumis and Citrullus. Hilgardia 3:233-250.
