Cucurbit Genetics Cooperative Report 10:39-40 (article 23) 1987
Further linkage studies in Cucumis sativus
L.
S. Zijlstra
Institute for Horticultural Plant Breeding (IVT), P.O. Box 16, 6700 AA Wageningen,
The Netherlands
In 1986 linkage studies for seven combinations of two different marker
genes have been continued at the IVT. Involved were the recessive marker
genes bi (bitterfree), cp (compact), ccu (susceptibility
to scab), lh (long hypocotyl), ro (rosette), gl (glabrous),
ul (umbrella leaf) and dvl (divided leaf).
Independent segregation was found in the F2's from the crosses
bi x cp, ccu x ih, ccu x ro, ccu
x cp and gl x lh, as can be seen from the low and nonsignificant
X2 values (Table 1). It was not possible to detect the umbrella
leaf (ul) plants reliably in the F2's of the crosses ro
x ul and ul x dvl. The expression of this character
in the parent line was also very poor, presumably because the climate was
not suitable. In the F2 of the cross ul x dvl the
divided leaf genotypes could not be clearly distinguished, in contrast to
the leaves from the dvl parent line. It is conceivable that the two
leaf shape mutants interact.
Until now, 15 combinations of marker genes have been analysed at the
IVT (1, 2, 3) in which 10 genes were involved. Linkage was detected only
for the genes dvl and gl (1), sp and ul (3)
and for sp and lh (3).
Table 1. Segregation and size (N) of F2 populations for linkage
tests, recombination percentage (%) and calculated chi-square ratio for
the 9:3:3:1 ratio (X2) for 5 pairs of genes.
++ indicates dominant allele was observed for both loci involved in the
cross, -+ indicates dominant allele for the first locus and 2 recessive
alleles for the second, etc.
Literature Cited
- Nijs, A.P.M. Den and I.W. Boukema, 1983. Results of linkage studies
and the need for a cooperative effort to map the cucumber genome. Cucurbit
Genetics Coop. Rpt. 6:22-23.
- Nijs, A.P.M. Den and I.W. Boukema, 1985. Short petiole, a useful seedling
marker for genetic studies in cucumber. Cucurbit Genetics Coop. Rpt. 8:7- 8.
- Zijlstra, S. and A.P.M. Den Nijs, 1986. Further results of linkage
studies in Cucumis sativus L. Cucurbit Genetics Coop. Rpt. 9:55.
