Cucurbit Genetics Cooperative Report 22:14-15 (article 6) 1999
D. Besombes, N. Giovinazzo, C. Olivier, C. Dogimont, and M. Pitrat
INRA, Station de Genetique et d’Amelioration des Fruits et Legumes, BP 94, 84143 Montfavet Cedex (France)
A spontaneous albino mutant of Cucumis melo L. has been observed ion ‘Trystrorp’, an accession from Sweden. Cotyledons are white and plants died one to two weeks after germination. Germination of the seeds was very high in different generations indicating no lethal effect on the embryos. Because homozygous plants cannot be used as female or male parents, only heterozygous plants can be used for inheritance studies.
The F1 between ‘Trystorp’ and ‘Vedrantais’ was backcrossed three successive times to ‘Vedrantais’ (a normal charentais type line). These plants were selfed after each backcross (BCXS1) in order to verify if they were heterozygous for albino or normal. All the heterozygotes were normal indicating that albinism is completely recessive. Selfed backcrosses segregating for albinism fit a 1:1 ratio (Table 1) in the different generations. the number of progenies fit a 3:1 ratio in the BC1 and BC2 , but in the BC3 and BC4 there was an excess of albinos (Table 2). The segregation observed on the total number of plants in the different progenies fits a 3:1 ratio. Therefore, the albino trait can be explained by the action of one recessive gene. No other albino mutants has been described to our knowledge. We propose this mutant be named albino with the symbol alb.
Table 1. Number of plants whose selfed progeny segregated for albino in successive backcrosses of the F1(‘Trystorp’ x Vedrantais’) to ‘Vedrantais’.
| Number observed | X² | ||||
| Segregating | Non-segregating | Ratio tested | Value | Probability | |
| BC1 | 9 | 5 | 1 : 1 | 1.143 | 29% |
| BC2 | 8 | 12 | 1 : 1 | 0.800 | 37% |
| BC3 | 10 | 7 | 1 : 1 | 0.529 | 47% |
| BC4 | 7 | 12 | 1 : 1 | 1.316 | 25% |
| Total | 17 | 19 | 1 : 1 | 0.111 | 74% |
Table 2. Segregation for albino observed in selfed BC progenies.
| Population | Number observed | X² | |||
| Normal | Mutant | Ratio tested | Value | Probability | |
| BC1S1 | |||||
|
11 | 1 | 3 : 1 | 1.778 | 18% |
|
41 | 15 | 3 : 1 | 0.095 | 76% |
|
48 | 11 | 3 : 1 | 1.271 | 26% |
|
32 | 8 | 3 : 1 | 0.533 | 47% |
| Total BC1S1 | 132 | 35 | 3 : 1 | 1.455 | 23% |
| BC2S1 | |||||
|
47 | 14 | 3 : 1 | 0.137 | 71% |
|
30 | 11 | 3 : 1 | 0.073 | 79% |
|
14 | 4 | 3 : 1 | 0.074 | 79% |
|
25 | 6 | 3 : 1 | 0.527 | 47% |
| Total BC2S1 | 116 | 35 | 3 : 1 | 0.267 | 61% |
| BC3S1 | |||||
| 97-1039 | 40 | 27 | 3 : 1 | 8.363 | 0.4% |
| 97-1040 | 60 | 28 | 3 : 1 | 2.182 | 14% |
| Total BC3S1 | 100 | 55 | 3 : 1 | 9.086 | 0.3% |
| BC4S1 | |||||
|
41 | 19 | 3 : 1 | 1.422 | 23% |
|
65 | 31 | 3 : 1 | 2.722 | 10% |
| Total BC4S1 | 106 | 50 | 3 : 1 | 4.137 | 4% |
| Total | 454 | 175 | 3 : 1 | 2.671 | 10% |