According to the last linkage map published by Mutschler et al. (1987), the 3 genes are thought to be located on chromosome 3, in the following order: bls (baby-lea syndrome, site 74), con (convalescens, site non specified), sf (solanifolia, site 111). A more precise localization of con would be desirable in order to test the linkage relations between pat-2 (parthenocarpic-2) and these 3 marker genes (see 2 following notes in this report).
We used marker genes bls (GCR 29), con (GCR 377) and sf (GCR 392). The GCR markers were received from Glasshouse Crops Research Institute, GB. Three F1 hybrids were carried out: (GCR 29 x GCR 377), (GCR 377 x GCR 392) and (GCR 29 x GCR 392).
1. Linkage test between bls and con. A total of 771 F2 plants from the cross (GCR 29 x GCR 377) were observed: 449 [+ +], 125 [bls +], 150 [+ con], 47 [bls con]. Probability (X^2 for hypothesis of segregation 9:3:3:1): 0.20 < P < 0.30.
2. Linkage test between con and sf. A total of 789 F2 plants from the cross (GCR 377 x GCR 392) were observed: 449 [+ +], 142 [con +], 141 [+ sf], 57 [con sf]. Probability (X^2 for hypothesis of segregation 9:3:3:1): 0.50 < P < 0.70.
3. Linkage test between bls and sf. A total of 394 F2 plants from the cross (GCR 29 x GCR 392) were observed: 211 [+ +], 78 [bls +], 96 [+ sf], 9 [bls sf]. Probability (X^2 for hypothesis of segregation 9:3:3:1): P < 0.01. Recombinant [bls sf] plants were crossed with the F1 hybrid (GCR 29 x GCR 392). A total of 697 plants from this testcross were observed: 114 [+ +], 247 [bls +], 222 [+ sf], 114 [bls sf]. Probability (X^2 calculated for hypothesis of segregation 1:1:1:1): P << 0.01.
From these findings, it would be possible to conclude that bls and con are independent, as are con and sf. These results are not in concordance with those of Mutschler et al. (1987). According to our results, the loci of bls and sf are linked; the calculated distance: 32.71 +/- 3.55 units of co, compares closely with the 37 units given by Mutschler et al.
Literature cited:
Mutschler, M.A., S.D. Tanksley and C.M. Rick 1987 Linkage maps of the tomato (Lycopersicon esculentum). Tomato Genetics Cooperative Report 37: 5-34.