Further linkage studies in Cucumis sativus L.

admin

Cucurbit Genetics Cooperative Report 10:39-40 (article 23) 1987

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.

table 1

++ 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

  1. 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.
  2. 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.
  3. Zijlstra, S. and A.P.M. Den Nijs, 1986. Further results of linkage studies in Cucumis sativus L. Cucurbit Genetics Coop. Rpt. 9:55.