Cucurbit Genetics Cooperative Report 17:122-124 (article 36) 1994
INheritance of Hard Rind in C. maxima x C. moschata Crosses
Koch, P.S. and P.T. Della Vecchia
Agroflora S/A, Caixa Postal 427, 12900-000, Braganca Paulista, SP, Brazil
Along with the development of cv. Alice (1), a bush type of C. maxima, we have selected a sister line with fruit carrying the hard rind trait. Because hard rind lines show good field resistance to fruit rotting, there is some interest in using it as the female parent in F1 seed production. Hard rind in C. pepo and C. andeana x C. maxima is determined by a single dominant gene (3). Herrington et al. (2) presented data from a cross between C. maxima x C. eucadorensis suggesting that hard rind was recessive to soft rind in this cross and that the C. maxima cv. Queensland Blue has a dominant gene (Hi) which inhibits the expression of hard rind. It was of interest to know whether this inheritance pattern would hold true for other C. maxima accessions and the inheritance of this trait in crosses between C. maxima x C. moschata.
Materials and Methods. This pedigree and main characteristics of the breeding lines and cultivars used in the present study are presented in Table 1. Inbred lines were selfed for at least three generations and cultivars were observed for at least two generations before use, and were uniform for the trait under investigation. F1 seeds were produced by crossing the C. maxima hard rind inbred line AF839L as the female parent with all other lines and cultivars. A segregating F2 population was obtained for the cross (AF839L x AF724). Two hard rind and four soft rind F3 lines during the summer season of 1991, and the F3 lines during the Autumn season of 1992. Rind classification was made after steaming pieces of the mature fruits for 10 minutes. Soft rinds disintegrate after this treatment, whereas hard rinds remain hard.
Results and Discussion. Hard rind in F1 plants of crosses between C. maxima x C. moschata was dominant to soft rind (Table 2). In all crosses between C. maxima x C. maxima lines or cultivars, hard rind in F1 plants was recessive to soft rind (Table 2). Segregation for the trait in the F2 and in the F3 (selected lines) generations did not differ significantly from the expected 3:1 and 1:0 ratios, based on chi-square values, for a single gene model of inheritance (Table 2). These data support that of Herrington et al. (2) and suggest that the Hi gene (Hard rind inhibitor) may be a common feature among the C. maxima cultivars. If this holds true for other C. maxima cultivars, it may be feasible to use hard rind lines as the female parents in F1 seed production in C. maxima x C. maxima crosses for a better control of fruit rot under tropical conditions.
Literature Cited
- Della Vecchia, P.T., P.E. Takazaki and A. Terenciano. 1991. "Alice": nova cultivar de morganga, Cucurbita maxima Duch, com habito de crescimento moita. Horticultura Brasiliera 9(1):27.
- Robinson, R.W., Munger, H.M., Whitaker, T.W. and Bohn, G.W. 1976. Genes of the Cucurbitaceae. HortScience 11:554-568 .
- Herrington, M.E. and Brown, P.S. 1988. Inheritance of leaf and fruit characteristics in Cucurbita maxima Duch. cv. Queensland Blue x C. ecuadorensis Cutler and Whitaker. Queensland J. Agr. & An. Sci. 45(1):45-48.
Table 1 Pedigree and main characteristics of the breeding lines and cultivars used in the study of the inheritance of hard rind in C. maxima x C. maxima and C. maxima C. moschata crosses.
Line or Cultivar Number |
Pedigree |
Origin |
Type |
Rind Plant Type |
| |
C. maxima |
| |
AF89 |
cv. Exposicao |
Brazil |
soft |
large indeterminate |
AF139 |
cv. Sumare |
Brazil |
soft |
large indeterminate |
AF600L |
(T4 x Delicious) S6 |
Brazil |
soft |
medium indeterminate |
| AF721 |
cv. Golden Nugget |
Australia |
soft |
bush |
AF723 |
cv. Jarrahdale |
Australia |
soft |
large indeterminate |
AF724 |
cv. Baby Blue |
Australia |
soft |
short indeterminate |
AF839L |
(Coroa x Zapallo de Tronco)S6 |
Brazil |
hard |
bush |
| |
C. moschata |
| |
AF543L |
Kurokawa S6 |
Japan |
soft |
medium indeterminate |
AF822L |
Aizuwase S3 |
Japan |
soft |
medium indeterminate |
| |
Table 2. Segregation patternfor rind texture in C. maxima C. maxima and C. maxima x C. moschata.
| |
|
Number of Plants |
|
|
|
Lines or Crosses |
Total |
Soft Rind |
Hard Rind |
Expected Ratio of Soft:Hard |
X2 |
P |
| |
| AF89 (C. maxima) |
12 |
12 |
0 |
|
| Af139 (C. maxima) |
11 |
11 |
0 |
| AF6001 (C. maxima) |
12 |
12 |
0 |
| AF721 (C. maxima) |
12 |
12 |
0 |
| AF723 (C. maxima) |
10 |
10 |
0 |
| AF724 (C. maxima) |
9 |
9 |
0 |
| AF89 (C. maxima) |
12 |
0 |
12 |
| AF543L (C. moschata) |
12 |
12 |
0 |
| AF822L (C. moschata) |
11 |
11 |
0 |
| |
|
|
|
| C. maxima x C. moschata |
| |
| AF839L x AF543L F1 |
25 |
0 |
25 |
|
| AF839L x AF822L F1 |
22 |
0 |
22 |
| |
| C. maxima x C. maxima |
| |
| AF839L x AF89 F1 |
21 |
21 |
0 |
|
| AF839L x AF139 F1 |
18 |
18 |
0 |
| AF839L x AF600L F1 |
23 |
23 |
0 |
| AFf839L x AF721 F1 |
25 |
25 |
0 |
| AF839L x AF723 F1 |
19 |
10 |
0 |
| AF839L x AF724 F1 |
23 |
23 |
0 |
| Af839L x AF822L F2 |
253 |
260 |
83 |
3.1 |
0.12 |
0.50-0.75 |
| |
| HR-11 AF839L x AF724 F3 |
51 |
0 |
51 |
0:1 |
|
| HR-2 AF839 x AF724 F3 |
45 |
0 |
45 |
0:1 |
| |
| SH-12 AF839L x AF724 F3 |
60 |
60 |
0 |
1:0 |
|
| SH-2 AF839L x AF724 F3 |
67 |
54 |
13 |
3:1 |
1.12 |
0.25-0.50 |
| SH-3 AF839L x AF724 F3 |
62 |
51 |
11 |
3:1 |
1.74 |
0.10-0.25 |
| SH-4 AF839L x AF724 F3 |
64 |
44 |
20 |
3:1 |
1.33 |
0.10-0.25 |
| |
1 HR = Hard rind
2 SH = Soft rind
