Interaction and Linkage Tests of Flesh Color Genes in Cucumis melo L.

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Cucurbit Genetics Cooperative Report 15:53 (article 18) 1992

Carl D. Clayberg
Department of Horticulture and Forestry, Kansas State University, Manhattan, KS 66506-4002, USA

The melon genes green flesh (gf) and white flesh (wf) have each been reported to be inherited as simple recessives to orange flesh (2, 3). However, their interaction has not been described. I determined the interaction, using all three types in crosses. The orange-fleshed parent was a bush (si-1) crenshaw cultivar I recently developed, which had been inbred through F7 and showed no segregation for flesh color. The green-fleshed parent was an advanced breeding line homozygous for flesh color and bush habit and derived from a cross of the bush crenshaw with the honeydew cultivar Earlidew. The white-fleshed parent was the casaba cultivar Goldeb Beauty (Burpee Seed Co.). Results for the three possible crosses are given in Table 1. F1 flesh color in Tests 2 and 3 was orange and in Test 1 was white. Test 3 represents the pooled data for five different F2 families, each from a different F1 plant, but all five F1 ‘s from a single P1 x P2 cross. The data were pooled following a heterogeneity chi square test (XT2 = 7.79, p>0.50). Family size differed among the three tests, because they were also being used to advance my breeding program.

As can be seen from Test 3, wf+ is epistatic over gf +-gf. My orange-fleshed parent was wf+ / wf+ gf+/ gf+ , not wf+/wf+ gf / gf . This suggests that the crosses of Hughes (2) and Baines and Kang (1) of gf by gf+ , which gave no white-fleshed segregants, either involved wf+/ wf+ gf / gf parents or the authors were misclassifying white-fleshed segregants, assuming that wf and gf in my material and theirs is the same. The variability I encountered in gf phenotypes could lead to such misclassification, and indeed I did observe a deficiency of gf and an excess of wf phenotypes in comparison to be expected in Test 3 (Table 1).

No linkages were encountered among the three genes gf, wf, and si-1.

Table 1. Summary of linkage tests.

Test no.z

Generation and phasey

Gene combination

Observed frequencies
a
b
++
+b
a+
ab
x2x
p
1 F2 R si-1 gf 104 33 35 8 1.05 >0.70
2 F2 R si-1 wf 54 17 12 4 1.86 >0.50
3 F2 C wf gf (619) 166 41 2.97 >0.20

z Tests 1 and 2 are each of a single family; 3 is of 5 homogeneous, pooled families. Parental flesh colors were green x white in Test 1, orange x white in Test 2, and orange x green in Test 3.
y C = coupling; R = repulsion.
x Chi squares were calculated for fit to independent assortment, i.e., to a 9:3:3:1 in 1 and 2, and to a 12:3:1 in 3.

Literature Cited

  1. Baines, M.S. and U.S. Kang. 1963. Inheritance of some flower and fruit characters in muskmelon. Indian J. Genetics and Plant Breeding 23:101-106.
  2. Hughes, M.B. 1948. The inheritance of two characters of Cucumis melo and their interrelationship. Proc. Amer. Soc. Hort. Sci. 52:399-402.
  3. Imam, M.KL., M.A. Abo-Bakr, and H.Y. Hanna. 1972. Inheritance of some economic characters in crosses between sweet melon and snake cucumber. I. Inheritance of qualitative characters. Assiut J. Ag. Sco. 3:363-380.